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32. The anatomy, histology and development of the uterine tube and uterus.

2 Jan

32. The anatomy, histology and development of the uterine tube and uterus.

Anatomy of Uterus/Uterine Tube

Uterus:

Location: b/w bladder (ant) and rectum (post), above and leads to vagina

Function: Major organ of gestation

General Info:

7-8 cm long, 5-7 cm wide, 2-3 cm wide
2 main parts = corpus (upper 2/3) and cervix (lower 1/3) , connected via isthmus

  • Cervix protrudes into vagina @ angle of 60-70 degress = anteversion ( angle b/w vagina and cervical canal)
  • Body inclines forward and bends over fundus of bladder, attached to cervix w/ angle of another 60 degrees = anteflexion ( angle b/w jxn of cervix and body)


Topography:

  • ant = fundus of bladder
  • post = coils of SI, and via pouch of Douglas, the rectum
  • lat = cardinal ligament @ level of cervix (part of parametrium), that carries the uterine a/v
  • sup = fundus of uterus touches SI coils
  • inf = supported by pelvic diaphragm, UG diaphragm, round, broad, lateral cervical ligaments, pubovesical, sacrocervical, retro-uterine ligaments


Parts:

Cervical portion:
has 2 areas:
Vaginal portion – protrudes into vagina,surrounded by vaginal fornices

  • has rounded end and ext os of uterine canal w/in it
  • @ ext os, simple columnar epith –> str squamous
  • If no kids (nulliparous) – opening is round, and small
  • If kids (multiparous) – opening is slit like


Supravaginal portion – embedded into CT of visceral pelvic fascia (via parametrium), in direct contact w/ broad ligament (myometrium)

Cervical Canal:

  • terminal portion of uterine cavity
  • has impermeable plug of mucus,
    • helps prevent entrance of pathogens
    • that becomes permeable during ovulation –
    • does allow sperm to penetrate
  • b/w cervix and isthmus of uterus = int histological os – where wall of cervix changes to uterus histologically


Epith of cervix isn’t shed in menstruation like the epith of rest of uterus = simple columnar, # of glands inc in this area – they secret the mucus to make mucus plug
keeps closed until few hours before birth – then begins to dilate to allow head thru – this is due to high amt of collagen and smooth M in cervix

Cervix doesn’t have real myometrium, called it, but really has less smooth m and more elastic fibers compared to rest of uterus

NOTE: (Please do not be confused by the 50 names out there for the same thing)

  • Int opening of isthmic canal = anatomical int os (does not exist in pregnancy)
  • Int opening of uterus = int os = histological int os = external opening of isthmus (isthmic canal)
  • Ext opening of uterus = external os

Corpus

Biggest part of uterus
covered by broad ligament = called the mesometrium of uterus, attaches it to lateral body wall
bends over the bladder (ant)

Has two special parts : fundus & isthmus
Fundus

  • area above the level of uterine tubes
  • laterally, ends in uterine horns –> lead to uterine tube


Isthmus

  • narrow part locared b/w cervix & corpus of uterus
  • same histological structures as corpus of uterus
  • incorporated into cavity of uterus during pregnancy – @ 2nd 1/2 of pregnancy, isthmus opens up, so anat int os ceases to exist, only histo os and ext os still there
  • isthmic canal – canal w/in the isthmus
  • Int anatomical os – b/w isthmic canal and uterine cavity


Wall of Uterus
Perimetrium = outer layer, peritoneum & underlying subserosa
Myometrium = middle musc layer, has sublayers
Endometrium = innermost layer, layer removed during menstruation

Ligaments of Female Pelvis

  1. Broad ligament of uterus – 2 layers of peritoneal covering, from lat margin of uterus –> lat pelvic wall
    • holds uterus in position
    • contains: uterine tube, a/v, round ligament, ovarian ligament proper, urete, uterovaginal n. plexus, lymph vessels
  2. Mesovarium – fold of peritoneum that connects ant surface of ovary w/ post layer of broad ligament
  3. Mesosalpinx – fold of broad ligament that suspends the uterine tube
  4. Mesometrium–  fold of broad lig below mesosalpinx, and meso-ovarium, lat wall of uterus –> pelvic wall
  5. Proper Ovarian ligament – fibromusc cord from uterine end of ovary –> side of uterus below uterine tube w/in broad lig
  6. Suspensory ligament of ovary – band of peritoneum that runs sup/lat from end of ovary –> pelvic wall, has ovarian a/v, lymph vessels
  7. Lat/Transverse Cervical (Cardinal) Lig of Uterus (aka ligament of Mackenrodt’s) – fibromuscular condensations of pelvic fascia from cervix (hence, cervical) & lat fornix of vagina –> pelvic wall, run w/in parametrium of uterus
  8. Parametrium – fibrous CT that runs w/in mesometrium, connects uterus to lat pelvic wall
  9. Paracolpium – fibrous CT that connects the lat wall of vagina –> lat pelvic wall, fibers merge w/ those of para cysticum (for bladder)
  10. Pubocervical ligament – firm bands of CT from post surface of pubis –> cervix of uterus
  11. Sacrocervical(uterine) ligament – firm fibromuscular bands of pelvic fascia from lower end of sacrum –> to cervix, upper end of vagina *palpable in rectal exam
  12. Pubovesical ligament – pelvic fascia bands from neck of bladder (or prostate in male) –> pelvic bone
  13. Rectouterine ligament – holds cervis back and up and sometimes elevate a shelf-like fold of pertioneum (recto-uterine folds – called sacro-genital folds in male)
    • isthmus of uterus –> post wall of pelvis, lat to rectum
Ligament relations of Uterus & Uterine tube

Ligament relations of Uterus & Uterine tube

ligaments-of-female-pelvis-ct

Connective tissue ligaments of female pelvis


Also, peritoneal covering over pelvic organs in female create 2 pouches:
1. Vesicouterine Pouch

  • ant = bladder
  • post = uterus
  • lat = vesicouterine folds


2. Rectouterine pouch – aka Douglas pouch

  • ant = uterus
  • post = rectum
  • lat = rectouterine folds
  • floor = post fornix of vagina, in direct contact w/ ampulla of rectum *can be felt there via rectal exam


CLINICAL NOTE: This is deepest point of peritoneal cavity in female, any excess peritoneal fluid will collect there
blood in pouch can indicate the presence of ectopic pregnancy

Pouces and ligaments/Topography of Female Pelvis

Pouces and ligaments/Topography of Female Pelvis

Blood Supply: primarily uterine a, secondarily ovarian a

  • Uterine a enters parametrium via cardinal ligament of ovary
    • when it reaches isthmus, divides into large asc uterine br
    • small desc uterine br
    • also has ovarian and tubal br
    • @ cardinal lig  – uterine a/v crosses ureter and have vessels in fromt
  • Ovarian a
    • has ovarian and tubal br that anastomose w/ same br of uterine a
  • Veins = uterovaginal plexus of veins –> int/ext iliac v
blood-supply-uterus-vagina-ovary-uterine-tube

Blood Supply of Uterus, Uterine tube


Lymph Drainage:
1. Fundic region = aortic nodes via ovarian lymph vessels
2. Corpus = ext iliac and sup inguinal nodes
3. Cervix = int iliac and sacral nodes

Nerve Supply = branches of hypogastric n plexus,

Uterine Tube:
non united part of Mullerian duct (embryo)
Location: from horn of uterus –> ends in ampulla @ uterine end of ovaries

Function:

  • carries fertilized or unfertilized ovum from ovary to uterus, for Implantation
  • via action of the cilia on its epithelium, and contraction of musc wall, also carries sperm towards the ovary
  • Connects uterine cavity w/ peritoneal cavity
  • Fertilization occurs in ampulla or infundibulum of uterine tube


Parts:
1. Infundibulum – funnel-shaped distal portion over end of ovary

  • has 20-30 fimbriae, which attach to ovary
  • move to guide oocyte in after ovulation
  • communicates w/ peritoneal cavity via abdominal ostium


2. Ambulla – FERTILIZATION

  • widest and longest part of uterine tube
  • INTRAPERITONEAL
  • attached w/in broad ligament via mesosalpinx


3. Isthmus –
short 2.5 cm long area that leads to horn of uterus

4. Uterine part

  • part that attaches to uterine wall
  • opens into uterine cavity via  uterine ostium


Blood supply
= tubal br of ovarian and uterine a, veins run w/ a

Lymph drainage = run to aortic/lumbar nodes

Nerve supply = pelvic/ovarian n. plexus, that run in mesosalpinx

Minimals related to this topic:

minimal-125-sagittal-section-female1

196.    Describe the relation of the ovary to the uterine tube!
The upper or tubal end of the ovary is closely related to the uterine tube. The infundibulum has irregular fringes called fimbriae that project from the margin of the infundibulum to the ovary.
197.    Define the term “broad ligament of the uterus” and list those structures that are located within its substance!
A double layered peritoneal ligament extending from the sides of the uterus to the lateral walls and the floor of the pelvis.
Structures: uterine tube, round lig. of uterus, ovarian lig., epoophoron, paroophoron, uterine vessels, uterovaginal venous plexus, nerves.

198.    Define the term “parametrium”!
The loose connective tissue found between the two diverging layers of the broad ligament of uterus, which connects the lateral part of the cervix with the pelvic wall.
199.    Define the position of the uterus under normal conditions?
In the axis of the true pelvic, in anteflexion (bends forward) and anterversion (inclines forward)

200.    Define the term anteflexion and anteversion of the uterus!
Anteversion: the cervix is inclined anteriorly at an acute angle (appr. 60°-70°) to the vagina.
Anteflexion: the body of the uterus is bent anteriorly at an acute angle (appr. 60’-70’) to the cervix.

201.    Describe visceral relations of the uterus!
anterior    : posterior wall of bladder,
posterior    : anterior surface of rectum, small intestines,
above    : small intestines,
lateral    : ureter, before its opening into the urinary bladder.

202.    What is the epithelium of the a.) cervical canal and b.) vaginal portion of the uterus?
simple columnar mucous producing epithelium, with scatterd ciliated cells,
stratified squamous non keratinizing epithelium.

203.    Describe the peritoneal relations of the uterus!
The body and the posterior aspect of the supravaginal portion of the cervix is enclosed between the two layers of the broad ligament. The peritoneum reflects from the uterus posteriorly to the rectum and anteriorly to the urinary bladder forming the rectouterine and vesicouterine pouches, respectively.

204.    Define the term “Douglas pouch”?
Rectouterine pouch. Reflection of the peritoneum from the rectum to the uterus. The deepest point of the peritoneal cavity.

205.    List those structures that help to fix the uterus in its original position!
Vagina, pelvic and urogenital diaphragms, round lig., ovarian lig., vesicouterine fold, rectouterine fold, thickenings of the visceral pelvic fascia, broad lig., parametrium.

206.    Which lymph nodes receive lymph from the a.) fundus, b.) body and c.) cervix of the uterus?
aortc, external iliac, superficial inguinal lymph nodes,
external iliac lymph nodes,
internal iliac and sacral lymph nodes.

mnimal-207-inner-surface-of-uterus

Histology of Uterus/Uterine Tube

Slide #76 Uterus, Proliferative phase

Structures to Identify:

  • all layers of wall
  • simple columnar lining epithelium
  • simple tubular glands
  • a/v – arteries have a fused tunica mucosa
  • LP w/ spinocellular CT

General Info:

  • Endometrium (same as mucosa) changes with menstrual cycle
  • Menstrual cycle
    • Day 1-5 = Menstruation
    • Day 5-6 Regeneration
    • Day 6-14 Proliferative/Estrogen phase
    • Day 14-28 Secretory/Progesterone/Luteal phase
  • Uterus provides the site of implantation of fertilized embryo and formation for placenta
  • Note that the embryo grows within the wall of the uterus, causing the lumen to narrow, and forms a separate amniotic sac – the embryo does not grow in uterus lumen per se.

Endometrium

  • innermost layer, is equivalent to mucosa in other slides
  • changes made in endometrium based on hormones produced by ovaries
  • To tell that it is Uterus look for: v THICK mucosa, with loads of glands, and is very basophillic

Epith

  • simple columnar epith (ciliated and non ciliated cells)
  • epith is lower because this is the start of the cycle
  • non-ciliated cells will secret hormones in second part of cycle

LP

  • cell rich CT highly vascularized
  • simple tubular glands – inactive in this  stage
  • b/w glands, spinocellular CT & a/v
    • the endometrial stroma, which resembles mesenchyme
    • is highly cellular+ contains abundant intercellular ground substance.
    • cells  = stromal cells like in ovary
  • thickness depends on stage in cycle
  • Has two layers = Statum Functionalis superiorly, and Stratum Basalis inferiorly
  • Blood Supply:
    • RADIAL ARTERIES, (branches from the arcuate arteries in myometrium), enter the basal layer of the endometrium, where it give off small straight arteries that supply this region of the endometrium.
    • The main branches of the radial artery continous upward, become highly coiled SPIRAL ARTERY
    • Spiral arteries give off numerous arterioles, that often anastomoses, as they supply a rich capillary bed.
    • Lacuna= dilated segmants, may also occur in the venous system, that drains the endometrium.
    • The straight arteries+ the proximal part of the spiral arteries do not change during the menstrual circle.
    • The distal portion of the spiral ateries undergoes degeneration+ regeneration, with each menstrual cycle, under the influence of estrogen+ progesteron.
Note the smooth and oval glands in the endothelium = def proliferative phase uterus

Note the smooth and oval glands in the endothelium = def proliferative phase uterus

Stratum Functionalis

  • the one that proliferate+ degenerate during menstrual cycle
  • during this phase of the menstrual cycle, the endometrium varies from 1 to 6 mm in thickness.
  • UTERINE GLANDS(simple tubular): surface epithelium invaginate into the underlying lamina propria, the endometrial stroma.
  • containing fewer ciliated cells
  • If the glands are oval and smooth in the section, then you know it is proliferative stage.
  • Separated into upper Compact Layer, and inner Spongy layer

Stratum Basalis

  • minimal changes in the is layer between stages in the uterus
  • regeneration of epithelium starts from the stromal cells and glands in this layer
  • large amount of cells int his layer – even more so than in basal layer

NO MUSC MUCOSA/ SUBMUCOSA separate the endometrium from the myometrium.

Myometrium


  • is the thickest layer of the uterine wall

  • composed of 3 undefined layers of smooth muscle bundles: you see cross, oblique, longitudinal sections.

  • the smooth muscle bundles in the inner+ outer layers are predominantly oriented parallel to the long axis of the uterus.

  • muscle separated by interstitial CT
  • lots of a/v. —> tunica media of arteries merges with smooth m of the myometrium
  • arcuate a in myometrium =  vascular zone
    • separates the uteine wall into three zones – Supra vascular, vascular, and perivascular below.
    • 6- 10 arcuate arteries coming from the uterine artery that anastomose in the myometrium

Perimetrium

  • adventia/serosa
  • on sup surface of uterus, covered with peritoneum –> serosa
  • In other surfaces of uterus, is infraperitoneal –> covered with  adventia
  • If adventia, can possibly see ggl cells and nerve cells

PROLIEFERATING PHASE REGULATED BY  ESTROGEN:

  • at the end of the menstrual phase, the endometrium consits of a thin band of CT(about 1 mm) thick, containing the basal portion of the uterine gland+lower portion of the spiral arteries. = stratum basale the layer, that was sloughed off was the stratum functionale.
  • Stromal, endothelial+ epithelial cells in the stratum basale proliferate rapidly, following changes can be seen:
  • Epithelial cells in the basal portion of the glands reconstitute the glands &  migrate to cover the denuded endometrial surface.
  • Stromal cells:  proliferate, secrete collagen, & ground substance
  • Spiral arteries lenghten, as the endometrium is reestablished, these arteries are only slightly coiled+ do not extend into the upper third of the endometrium.
  • Continous until 1 day after ovulation, which occurs at about day 14, of a 28- day cycle.
  • At the end of this phase, the endometrium has reached a thickness of about 3 mm.
  • The glands have narrow lumina+ relatively straight, but have a slightly wavy appearance.
  • Accumulation of glycogen are present in the basal portion of the epithelial cells.

Slide #77 Uterus, Secretory phase

See the white space between the cells of stroma? And the twisted glands? = Secretory Phase Uterus

See the white space between the cells of stroma? And the twisted glands? = Secretory Phase Uterus

Structures are the same as listed above, with some key differences

Endometrium

  • Stratum functionalis –

    • MUCH thicker,
    • uterine glands are now larger and wavy, not oval shaped –> increase size due to secretion within

      • inside of glands are pale because secretions are mostly carbs
    • arteries are also more coiled , and become more prominent in this layer
      • increase in volume, to prepare for menstruation, the next phase
  • Stratum basalis –

    • less cells in interstitial tissue, more white space between cell
    • the increased interstitial fluid between the cells is called Interstitial EDEMA
    • more WBC, monocytes, neutrophils, granulocytes
    • straight a in this layer —> coiled arteries in fuctional layer
  • Stromal cells become decidual cells –> preperation for formation of placenta

Myometrium

  • more smooth m fibers

SECRETORY PHASE IS REGULATED BY PROGESTERON

  • The stimulation for transformation is the implantation of the blastocyst.
  • Large, pale cells rich in glygogen result from this transformation,
  • they create a specialized layer that facilitates the seperation of the placenta from the uterine wall at the termination of pregnancy.

Menstrual phase *Dont need to know for test, just theory to understand *

  • results from a decline in the ovariation secretion of progesterone+ estrogen
  • CORPUS LUTEUM produces hormones for about 10 days if fertilization does not occur.
  • As hormone levels rapidly decline, changes occur in the blood supply to the stratum functionale.
  • Periodic contractions of the walls of the spiral arteries, lasting for several hours, cause the stratum functionale.

Periodic conctraction of the walls of the spiral arteries, lasting for several hours stratum functionale to become ischemic.

  • Glands stop secreting+ the endometrium shrinks in heigh as the stroma becomes less edematous.
  • After about 2 days, extended periods of arterial contraction, with only brief periods of blood flow, cause disruption of the surface epithelium+ rupture of the blood vessels.
  • When spiral arteries close off, blood flows into the stratum basale, but not in the stratum functionale.
  • Blood, uterine fluid+ sloughing stromal+ epithelial cells from the stratum functionale constitute the vaginal discharge.
  • As patches of tissue separate from the endometrium, the torn ends of veins, arteries+ glands are exposed.
  • In the absence of fertilization, cessation of bleeding would accompany the growth+ maturation of new ovarian follicels.
  • The epithelial cells would rapidly proliferate+ migrate to restore the surface epithelium as the proliferative phase of the next cycle begins.
  • In the absence of ovulation( a cycle refered to as an anovulatory cycle), a corpus luteum does not form, and progesterone is not produced.
  • In the absence of progesterone, the endometrium does not enter the secretory phase until menstruation.

Slide #76 Uterus, Pregnant * H&E

Structures to Identify

  • endometrium with glands = decidua basalis
  • myometrium
  • chroion frondosum (primary villi)
  • embryonic cavity
  • primary, secondary, tertiary villi
  • chorion leave
  • decidua capsularis, marginalis, parietalis
  • a/v

General Info:pregnant-uterus

This slide is not as difficult as it may seem.  Look at the picture to the right to first familairize yourself with the layers listed.

First look for a long white tube with a thick wavy over covering –> this is the embryonic (amniotic) cavity.

  • On one side of it is chorion frondosum, with all the villi inside
  • Villi contain fetal blood
    • between the villi is the intervillus space that houses maternal blood
  • lateral to the chorion frondosum, is decidua basalis
  • on the other side of the amniotic cavity, is the chorion laeve, with the decidua capsularis lateral to that.

Villi

  • Villi are projections from the decidua that house branches of the uterine a/v, and contain fetal blood
  • they project into the space between the decidual layers.
  • maternal blood surrounds them in intervillous space
  • Free gas exchange occurs between the villi and intervillous space
  • 2 types of villi: anchoring villi (attached to chorion), floating villi (free floating)
  • made from trophoblast cells – which makes two layers of cellssyncytiotrophoblast (outer) & cytotrophoblast (inner)
  • Primary villus
    • 2 layers of trophoblast cells only
  • Secondary villus
    • 2 layers with extra embryonic mesoderm in w/in
    • light center – look for white space in center
    • may have small a/b near the center
  • Tertiary villus
    • the largest ones
    • only syncytiotrophoblast layer, much bigger, with a/v near periphery

Slide #74 Uterine Tube * H&E

Labyrinth like lumen of Uterine tube

Labyrinth like lumen of Uterine tube

Structures to Identify:

  • simple columnar epithelium
  • peg cells (right ovulation, might not be there)
  • LP
  • muscular layer
  • a/v
  • mesothelium (cells of perimetrium)
  • adipocytes

Lumen: very labyrinth like – looks like a fern

  • protrusion into lumens from mucosa
  • amt of labyrinth depends  on location where section was taken –> less in infudibulum, more closer to uterus
  • Do NOT confuse with Prostate. The folds look similar, but there are no prostatic calcifications, and there is only one lumen here, not a bunch of small fuzzy tubules
  • Epith and LP of Uterine Tube, with ciliated and peg cells shown

Epith

  • simple columnar epithelium – do NOT say psuedo stratified
  • some cells ciliated
    • these are shorter and have less cilia at times,
    • After ovulation , are taller with more cilia,
    • depending on hormones released in ovarian cycle (estrogen)
  • thickness changes w/ menstrual cycle
  • the non ciliated cells = peg cells
    • secrete mucin = carbs for sperm
    • expelled from epith when dead (die after excreting their mucin)
    • project into lumen
    • look like nails
    • look for long cells in a bump on top of epith
  • During proliferative phase of uterus, with increase amount of estrogen, the cilated cells become larger and have more ciliae – peg cells secret more mucin

L.P.

  • loose CT, with a/v
  • numerous fibroblasts with collagen and reticular fiber
  • supports the CT papilla projections into the mucosa

No Musc. mucosae or Submucosa

Muscular coat (Musc ext)

  • inner ciruclar, outer longitudinal layers
  • more developed closer to uterus
  • has PNS ggl/nfibers – may be able to find them

Outer coat = serosa

  • made of double layer of broad ligament with a/v inside
  • made of mesothelial cells
  • has a/v + adipocytes

Embrology of Uterus/Uterine Tube

  • PARAMESONEPHRIC DUCTS develop into the MAIN GENITAL DUCTS OF THE FEMALE.

  • 3 parts can be recognized in each duct:

    • a cranial vertical portion that opens into the abdominal cavity

    • a horizontal part that crosses the mesonephric duct

    • a caudal vertical part that fuses with its partner from the opposite side.

  • With descent of the ovary, the first 2 parts develop into the uterine tube+ the caudal parts fuse, to form the uterine canal.

  • When the second part of the paramesonephric ducts moves mediocaudally, the urogenital ridges gradually come to lie in a transverse plane.

  • DUCTS fuse in the midline, a broad transverse pelvic fold is established.

  • BROAD LIGAMENT OF THE UTERUS: fold, which extends from the lateral sides of the fused paramesonephric ducts toward the wall of the pelvis.

  • The uterine tube lies in its upper border, and the ovary lies on its post. Surface.

  • UTERORECTAL POUCH+ UTEROVESICAL POUCH are devided by the uterus+ broad ligaments

  • CORPUS+ CERVIX of the uterus coming from the fused paramesonephric ducts.

  • MYOMETRIUM(= muscular coat of the uterus)+ Peritoneal covering(perimetrium) = layer of mesenchyme

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29. The anatomy, histology and development of the kidney.

29 Dec

29. The anatomy, histology and development of the kidney.

* Kidney is one of the 2 primary retroperitoneal organs, and is not part of the primary gut.

Anatomy of Kidney

Location: In middle compartment of retroperitoneal space, within the renal fascia, along with suprarenal gland. Located in paravertebral gutter against psoas major m.

SP – B/w T123 – L3/4, beside IVC/ab aorta B/c R lobe of liver is larger than the left, the R kidney is situated slightly lower than the left. The left kidney projects at the 11-12rib, and R is the 12th rib only.

Topography:

  • R Kidney – (ant) – Liver, gallbladder, duodenum, R suprarenal gland, R colic flexure, asc colon, loops of SI

  • L Kidney – (ant) suprarenal gland, stomach, spleen, pancreas, L colic flexure, SI, desc colon

  • Both Kidneys – (post) – (sup) diaphragm, (inf, from lat to med) transverse m aponeurosis, quadratus lumborum m, and psoas major m.

Fxn – prod and excrete urine, filter waste from blood, and maintain electrolyte balance, and regulate BP by producing vasoactive substances.

Parts:

External structures:

Kidney has 3 coverings:

Renal fascia – that covers both kidneys like a huge tent like structures, separates the retroperitoneal cavity into 3 compartments.

This renal fascia also divides the fat that surrounds the kidney into two layers =

  • inside the renal fascia, is perirenal fat, between the capsule of the kidney fascia.

  • Outside the renal fascia is the pararenal fat. (Peri means around it , like perimeter, and Para means next to, or almost in but not quite, like paranormal, or paraplegic)

Each kidney then as a separate adipose layer, within the fascia is perirenal fat.

Lastly, each kidney has a fibrous capsule, called renal capsule. This capsule, unlike in other organs, does not send CT septa into the kidney and is therefore removable easily.

Renal sinus – is the inner cavity of the kidney (not part of parenchyme, the tissue stuff, just an empty space), which leads the hilum of the kidney. Structures that enter/ leave here = renal a/v, minor calices, major calices, renal pelvis, lymph vessels, renal fat, ANS fibers

Renal hilum – entrance into the renal sinus. Ant–> post is located the renal v, a, then the ureter = VAU

Internal Structure:

Within each kidney, there is a an outer cortex, and inner medulla. Structures within the cortex and medulla will be discussed in further detail in the histology section.

Cortex: The cortex is the outer part of the kidney and projects into the inner medulla region, between the renal pyramids, as renal columns.

Medulla: The medulla is arranged into triangle shaped renal pyramids, that end in a renal papilla, which then lead into the minor calyx (each minor calyx drains one lobe of the kidney)

  • 3-4 minor calices join to form the major calices.

  • The major calices all join to form the renal pelvis –> that becomes the ureter.

  • The function unit of the Kidney is called the nephron. It is made up of a renal corpuscle ( made up of capillaries surrounded by the Bowman’s capsule, which has visceral and parietal layers. The renal corpuscle leads into a series of tubules surrounded by a arterial network, that aids in filtering urine.

Urine flow: From the urinary pole of the renal corpuscle –> prox convoluted tubule –> prox straight tubule –> desc limb, or desc part of thin segment–> Loop of Henle –> asc limb, or asc part of thin segment –> distal straight tubule –> distal convoluted tubule –> collecting duct –> papillary duct (at base of renal papilla) –> minor calyx –> major calyx –> renal pelvis –> ureter –> urinary bladder –> urethra

A longitudinal section, B nephron and adjacent blood vessels; 1 renal papilla, 2 renal column, 3 capsule, 4 renal pyramid, 5 calyx, 6 ureter, 7 renal pelvis, 8 renal vein, 9 renal artery, 10 interlobar artery, 11 arcuate artery, 12 interlobular artery, 13 interlobar vein, 14 cortex, 15 interlobular vein, 16 renal sinus, 17 arcuate vein, 18 medulla, 19 vasa recta, 20 loop of Henle, 21 collecting duct, 22 arcuate vein, 23 arcuate artery, 24 proximal convoluted tubule, 25 glomerulus, 26 Bowmans capsule, 27 distal convoluted tubule
kidney 1: A longitudinal section, B nephron and adjacent blood vessels; 1 renal papilla, 2 renal column, 3 capsule, 4 renal pyramid, 5 calyx, 6 ureter, 7 renal pelvis, 8 renal vein, 9 renal artery, 10 interlobar artery, 11 arcuate artery, 12 interlobular artery, 13 interlobar vein, 14 cortex, 15 interlobular vein, 16 renal sinus, 17 arcuate vein, 18 medulla, 19 vasa recta, 20 loop of Henle, 21 collecting duct, 22 arcuate vein, 23 arcuate artery, 24 proximal convoluted tubule, 25 glomerulus, 26 Bowman’s capsule, 27 distal convoluted tubule

Blood Supply

  • Arteries: Renal a supplies the kidney, located @ L1 of ab aorta, the 2nd paired visceral branch from the aorta

    • Renal a splits into 5 segmental branches –> each segmental br has ant/post br –> interlobar arteries, running within the renal columns –> splits into 2 arcuate arteries, which arch over the base of the renal pyramids –> interlobular a, within the cortical labyrinth between the medullary rays (will talk about these structures in histo, dont worry about them now) –> have arteriolar system that goes to the renal corpuscle and tubular system –> interlobular v –> rest of the v follow the arteries mentioned prev.

    • Renal a also gives inf supra renal a, and possibly branches to ureter.

  • Veins: Veins within kidney, follow arteries, until getting to renal v –> IVC R renal v is a little lower, and much shorter than L renal v, b/ c IVC is located on the right side of vert. column.

Lymph Drainage : Lymph vessels in the kidneys follow the arteries –> renal sinus –> hilum –> para-aortic and common iliac l.n. –> lumbar trunks –> cisterna chyli

Renal innervation: N. of kidney from the renal n plexus = PNS/SNS fibers, from ab/pelvic splanchnic n.

  • PNS = @ origin of renal a, is the location of the aortico-renal plexus, with pre-ggl fibers from all 3 splanchnic n (Greater, Lesser, Least) –> post ggl fibers –> organ

  • SNS = From T12 – L2 run through sympathetic trunk to least splanchnic n and lumbar splanchnic n, comes the pre ggl fibers –> renal ggl (not the same as aortico renal plexus) –> post ggl fibers –> kidney/ ureters

  • Most supply renal a/v and branches, to decrease urine production

  • PARS – PNS = Aortico-renal, Renal = SNS

Ureters

  • Pathway of Ureters = from renal hilum (lies most post. ) –> runs in retro peritoneal space, ant to psoas m, and crosses the bifurcation of the common iliac a, and rec. blood from those arteries.

  • Topography of ureter

    • R ureter – behind desc part of duod, post to root of mesentery, post to gonadal a/v

    • L ureter – post to left colic a/v, next to gonadal vessels, post to sigmoid a and sup rectal a (in sigmoid mesocolon)

    • Both = pass behind Ductus deferens (or cardinal ligaments/ uterine a/v in females), and enter bladder on the lower/post side.

  • Blood supply = branches from various a it passes

  • Innervation = W/in renal pelvis = least splanchnic n from T 12 Abdomen/pelvis = lumbar splanchnic n (SNS), Pelvic splanchnic n give PNS innervation along the entire ureter.

Suprarenal glands:

  • Location: on top of each kidney, medially, below diaphragm, is pyramid shaped on R side, and semilunar shaped on L side, also covered by renal fascia, and has a fibrous capsule.

  • Topography:

    • R = r lobe of liver (bare area), R kidney

    • L = Lesser sac, pancreas, L kidney

  • Parts:
    • Cortex –> prod steroid hormones, including mineralocorticoids (aldosterone), glucocorticoids (cortisone), and sex hormones

    • Medulla –> derived from embryonic neural crest cells, rec pre-ggl SNS fibers directly and secrets epinephrine and norepinephrine.

  • Blood Supply:

    • Arteries:

      • a) Sup suprarenal a – from inf phrenic a (ab aorta)

      • b) Mid suprarenal a – from aorta directly

      • c) Inf suprarenal a – from renal a

    • Veins

      • R suprarenal v –> IVC

      • L suprarenal v –> L renal v –> IVC

Histology = Kidney Slide # 60 * H&E


Structures to Identify:

  • renal corpuscles

  • renal column

  • renal pyramids

  • cortical labyrinth

  • medullary rays

  • Cortex

  • Medulla

  • Cortex corticis

  • a/v

  • renal corpuscles

  • tubular system

  • urinary pole

  • vascular pole

  • Juxta glomerular apparatus = macula densa, JG cells, (dont have to identify mesengial cells)

General Info:

  • Main organ of urinary system

  • conserve body fluids and electrolytes

  • remove metabolic wastes like urea, uric acid, and other debris

  • produce urine as ultrafiltrate of blodd that is modified by selective resorption /secretion by kidney tubule cells

  • 10cm long, bean shaped, between T12-L3

  • about 20-30 renal pyramids

Nephron is fxn’l unit of the kidney . There are two types of nephron, classified depending on their location within the kidney.
1. Cortical nephron – located anywhere in the cortex, long thick segments, short thin segments
2. Justamedullary nephron – located at the cortio-medullary border, near base of pyramid, where arcuate arteries are.  have short thick segments and long thin segments that go almost to the bottom of the renal pyramid. have more hypotonic enviroment, to produce a concentrated urine.

* Look the same with in slide.

Parts of nephron, in order of flow :
Renal corpuscles –> proximal convoluted tubule, proximal straight tubule, descending limb, loop of Henle, ascending limb, distal straight tubule, distal convoluted tubule.

Cortex

Cortex characterized by renal corpuscles and their tubules including convoluted and straight parts of nephron, the collecting tubules and extensive vascular network.

Renal corpuscle

  • Renal corpuscle consists of glomerular capillary bed surrounded by double layer of epith cap (Bowman’s capsule),

  • space between glomerulus and capsule is called capsular or urinary space.
  • Each capsule has afferent arteriole and efferent arteriole, and has two layers: a inner visceral layer, and outer parietal layer.

  • The visceral layer of the capsule surrounds the capillaries of the glomerulus with modified epithelial cells called podocytes.

  • There are two poles to the corpuscles = urinary pole, where there tubular system starts from, and the vascular pole, where the arterioles enter/exit

Blood enters corpuscles through specialize mechanism of corpuscle:  Filtration Apparatus, which is located in the area between the podocyte fingers and the endothelium of the capillaries.

Layers in barrier b/w capillaries and epith lining of Bowman’s capsule:

1. Glomerular Basement membrane

2. Podocytes lining capillaries assist GBM in further filtration via unique structures containing finger like structures called pedicles that interweave between each other.

3. The Slit Membrane

  • The basement membrane of the endothelium of capillaries and the basement membrane of the podocytes fuse,

  • each basement membrane has two layers: an outer fibrous membrane and an inner basal lamina.

  • the two fibrous membranes touch each other and fuse, forming one single layer.

  • Therefore, the filtration barrier between the capillaries and the podocytes is made up of the following layers:

    • 1. The endothelium of the a/v

    • 2. the glomerular basement membrane = made of three layers (GBM)

      • a) Lamina rara interna = the basal lamina of endothelium

      • b) Lamina densa = the fused 2 fibrous layers of the basement membranes of both endothelium of capillaries and podocytes

      • c) Lamina rara externa = the basal lamina of the podocyte

    • 3. The Slit membrane = CT covering the spaces between podocytes.

  • So picture it like this: Put your hands up together, and put your fingers between each other, but without clasping them together or weaving your fingers together. Picture your hands holding a giant messed up ball of yarn and then imagine cling film over your hands, covering the spaces between your fingers. The yarn is the glomerular capillary bed, your hands is the Bowman’s capsule (the palm being the visceral layer and outside skin being the parietal layer), and your fingers are the podocytes interdigitating, with the cling film between your “podocytes” is the slip membrane, covering the spaces between the podocytes.

  • Filtration happens in the cling film area, that is to say, that it only occurs between the podocytes, where the slit membrane is located

With in the cortex, one can also the see the next part of the nephron, the proximal convoluted tubule, and its counterpart on the way back from the loop of Henle, the distal convoluted tubule.


You have to be able to show both of them

Prox  convoluted tubule

  • simple cuboidal epith

  • v. visible BM

  • irregular lumen

  • border between cells indistinct

  • acidophillic cytoplasm = lots of mitochondria

  • brush border present

  • basal striations

Distal convoluted tubule

  • less in # than proximal in cortex

  • cytoplasm lighter

  • cell boundaries seen

  • very smooth wide lumen

  • cuboidal cells still

  • brush border cannot be seen (doesn’t mean it’s not there)

  • striations present, but not seen well

Juxtaglomerular apparatus

Between the renal corpuscle’s vascular pole and the distal convoluted tuble is a structure called the Juxta-Golmerular Apparatus, with 3 parts:.
1. Juxtaglomerular cells.

  • @ vascular pole,

  • smooth m. cells of tunica media of afferent arteriole is replace by epith-like cells with granules in cytoplasm =  Juxtaglomerular cells.

  • secrete renin as part of Renin-angiotensin system

2. Mesengial cells

  • Also in apparatus are mesengial cells (no need to locate)

  • chemoreceptor cells @ vascular pole

  • activated by sensing the ion concentration in blood in macula densa,

  • in other regions, help clean glomerular basement membrane

  • secrete erythropoeitin.

  • found with in and out of glomerulus, so named that  way = Extra glomerular, Intra glomerular mesengial cells

3.Macula Densa

  • Lastly, the distal convoluted tuble right next to the vascular pole will have cells next to the JG cells that are a bit different.

  • They are a darker row of cells on the side of the distal convoluted tube

  • just next to the vascular pole = Macula Densa.

Within the cortex, is also the medullary rays. Contain = proximal straight tubules, distal straight tubules and the collecting ducts.

NOTE – area of cortex above the level of medullary rays is called the cortex corticis.

The characteristics of the straight part of tubules pretty much same as convoluted, Just look for thin eosinophillic tube structures with fuzzy lumen = prox, and very thin tubules with almost no staining in wall = distal.

Collecting ducts
, not part of nephron, lumen is wide and the cells making up the wall is much bigger. usually widest lumens in this area. lightly stained cuboidal epithelium

Medulla
location of renal pyramids – remember that the base of the pyramid faces the cortex, and the apex of the pyramid (renal papilla) faces the hilum.

The cortex projects into medulla between renal pyramids as renal columns. (don’t have to show that)

Area between the medullary rays = cortical labyrinth

located where renal corpsucles end *NONE in medulla
contains only straight tubules, and asc and desc limbs of loop of Henle , as well as collecting tubules.

  • @ apex of pyramid, (bbttom of slide) on one side of slide, can see the edge of the renal papilla – where it enters the minor calyx. You will see a slit in the slide, with one side’s epith v. thick and pink related to the other side of the slide. This is where the transistion urothelium of the minor calyx turns into the columnar epithelium covering the papilla. The one more lateral (and thicker) is the minor calyx.
  • Also the location to find the papillary ducts. – large lumen, lined by tall columnar pale staining cells.
  • base of papilla has a stratified columnar epith
  • to identify the Loops of Henle

    • look for v. thin  tube like structures.

    • They look like thin capillaries

    • only with a thicker epithelium

    • simple squamous epithelium
    • no RBCs within their lumen.

    • To find them , you have to go alll the way down to the lower edge of the slide.

Blood Supply:

Blood flow in kidney v. different from other organs due its filtration function.

  • From renal a –> interlobular a (renal columns) –> arcuate a (at base of pyramid) –> interlobular arteries ( cortical labyrinth) –> give multiple afferent arterioles to renal corpuscle.

  • Here’s where it is different. Normally from capillaries you get venules leaving. In the kidney, instead, another arteriole leaves the glomerular capillary bed, the efferent arteriole

  • from renal corpuscle –> efferent arteriole –> this then forms a second capillary bed around the tubular system we’ve discussed. –> then venules come from this capillary bed, and the veins follow the arteries.

There are three types of arterial branch of the efferent arterioles:
1. Cortical nephrons – aff a –> glomerulus –> eff a –> 2nd capillary bed local to the first one –> venules

2. Juxta medullary nephrons – aff a –> glomerulus –> eff a –> doesnt break into 2nd capillary bed right away, instead follow tubules all the way down to medulla (long thin segment, remember?) into the pyramid  –> uturn  –> come back up –> venules These long arterioles following the long segments of tubules staight down into medulla are called the vasa recta.

3. Capsular nephron (minor) – located in cortex corticis, the eff. a can form a star shaped capillary bed just under the capsule of the kidney = stellate capillary bed.  Cannot be seen in slide.

Slide # 61 Kidney Tangential section

  • Same structures cut the opposite way. can see the cross section of straight tubules.

  • characteristics the same.

  • the bubble like, more clear area = medullary ray

  • Eosinophillic area = cortical labyrinth

  • find interlobular a here, about 6 around each column.

  • Identify same parts as first slide

Slide #62 Kidney * H&E + Indian Ink

  • Ink injected while animal is still alive, and H&E added posthumously

  • a/v stained black, so can see all parts of vascular system: glomeruli, arcuate a, vasa recta, stellate capillary bed seen at top, under capsule.

  • Star shape not visible due way of cutting.


Embryology of Kidney:

  • Intermediate mesoderm from long ridge on post (dorsal) body wall = urogenital ridge.

  • Part of this ridge = nephrogenic cord –> becomes urinary system

  • Nephrogenic cord  –> splits into pronephros, mesonephros, metanephros

  • Pronephros = most cranial, forms pronephric tubules, and pronephric duct, regresses in wk 5, not fxn’l in humans

  • Mesonephros = middle structures, from mesonephric tubules and ducts (Wolffian duct), fxn’l for only a short period of time. The duct will still exite, and opens into urogenital sinus.

  • Metanephros = most caudal, forms from outgrowth of mesonephric duct = ureteric bud, and from mesoderm grouping within nephrogenic cord called metanephric mesoderm. , forms @ wk 5, and fxn’l @ wk 10

  • The ureteric bud penetrates the metanephric mesoderm, and then divides to form: ureters, renal pelvis, major and minor calyces, and collecting ducts.

  • Collecting ducts push the metanepheric mesoderm to form vesicles (pouches), that become all the parts of the nephron.

Ascent of Kidneys:

  • metanephros located w/in sacral region, but ends up at level of T12-L3.

  • B/c of increase amt of growth caudal to metanephros.

  • While ascending, kidneys rotate 90 degrees, so hilum faces medially.

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