35. The anatomy, histology and development of the seminal vesicle and prostate gland.

35. The anatomy, histology and development of the seminal vesicle and prostate gland.

Anatomy of Seminal Vesicle & Prostate Gland

Seminal Vesicle:
*Retroperitoneal, except the tip, which is intraperitoneal

General Info:

• long tube (10-15cm), that coils down into 5cm
• produces seminal fluid – alkaline substance, w/ fructose, choline
• enclosed by dense endopelvic fascia
• are lobular glandulated structures that are actually pockets that formed off of the DD
• lower end becomes narrow & from ducts which join ampulla of DD –> make ejaculatory duct
• Does NOT store spermatozoa

Topography:

• @ post side of prostate
• located inf/lat to ampulla of DD, against the fundus of the bladder
• tip lie post to ureters, where peritoneum of rectovesical pouch separates it from rectum
• inf end separated from rectum via rectovesical septum

Blood Supply:

• inf vesicle a/v (int iliac a)
• middle rectal a/b (int iliac a)

Lymph Drainage: int iliac l.n.

Nerve Supply:
SNS – controls rapid contraction, during ejaculation – superior lumbar & hypogastric n
PNS – pelvic splanchnic n, inf hypogastric (pelvic) plexus

Ejaculatory Duct:

General Info:

• union of ductus deferens
• formed @ neck of bladder
• enters prostate @ post surface –> runs down, med, forward –> opens lateral to seminal collicus, on prostate urticle on post wall of prostatic urethra
• peristaltic contractions of musc layer of ductus deferens & ejaculatory ducts
• propel spermatozoa w/ seminal fluid into urethra

Blood Supply: deferential a (inf vesicle a)
veins –> prostatic and vesical venous plexus

Lymph drainage: ext iliac l.n.

Nerve supply: inf hypogastric plexus

Prostate
below the bladder, and is around prostatic urethra
prostatic capsule – has a dense CT fibrous capsule
prostatic sheath – has a soft CT capsule around fibrous one – derived from pelvic fascia
is continuous w/ paraproctium (the CT fibers around rectum), and paracysticum (CT fibers around bladder)

Two parts:
Glandular portion (2/3)
lat – make most of pass of prostate, lat to urethra
post – behind urethra, below ejaculatory duct CLINICAL NOTE – is palpable via rectal exam
med – around urethra, b/w it and ejaculatory duct

• Prostatic glands – produces seminal fluid that causes odor of semen
  • contains Prostatic specific antigen (PSA), prostaglandins, citric acid, acid phosphatase, proteolytic enzymes
  • make about 20% of seminal fluid
  • this fluid + secretions of seminal vesicles + secretions of bulbourethral glands + sperm = semen
• Urethral crest:
  • on post wall of prostatic urethra, and has # of openings for prostatic ducts on either side
  • has ovoid shaped enlargement called seminal collicus – where 2 ejaculatory ducts, prostatic utricle open
  • @ top of colliclus = prostatic utricle, small impression (analogous to female vagina)
• Prostatic sinus:
  • groove b/w urethral crest & wall of prostatic urethra
  • rec duct of prostate glands

Fibromuscular portion (1/3)
ant – ant to urethra, no glandular substance

Topography:

• ant = pelvic wall, musc fibers, has retroperitoneal fat in front of it, b/w it and pubic symphysis
• post = seminal vesicle, ductus deferens, ampulla of rectum
• sup = bladder
• inf = urethral sphincter, deep perineal m, UG diaphragm, levator ani

Blood supply: inf vesicle a, middle rectal a
drained by prostatic venous plexus (b/w  fibrous capsule & prostatic sheath) –> int iliac v

Nerve supply:
Both PNS/SNS to contract smooth m
PNS – pelvic splanchnic n (S2-S4)
SNS – inf hypogastric plexus

Histology of Seminal Vesicle & Prostate Gland

Slide # 69 Prostate *H&E

Structures to Identify:

• prostatic glands
• capsule
• glandular epithelium
• smooth m
• excretory ducts
• prostatic stones
• CT stroma

General Info:

• located inferior to neck of bladder
• seminal vesicle combine with the ductus deferens and open as ejaculatory duct here
• surrounded by dense CT capusle
• urethra leaves bladder and passes through bladder, and is called prostatic urethra.
• largest  accessory sex gland, several functional zones
• 30-50 glands arranged in concentric layers = mucosal, submucosal, and peripheral
  • Mucosal –> secrete directly into urethra
  • Submucosal/Peripheral –> secrete into urethra via ducts
• Secretions
  • Citric acid
  • Fibronalysin
  • Serine Protease (PSA) –> Clinical NOTE: if increased, can be early sign of prostatic cancer

Epith: transitional (urothelium) epithelium

Prostatic Glands

• look like popcorn
• have glandular epith = simple columar epith –> cuboidal
• are small, branched tubulo acinar glands
• may have circular very pink prostatic stones
  • calcifications of cellular debris in the gland
  • # increases with age
  • Very characteristic of prostate. — LOOK FOR THESE, if u think it is the prostate.
• between glands = fibromuscular stroma, with loads of smooth m bundles, and collagen and elastic fibers

Prostatic stones

The stroma encircles an area called the seminal collicus, that has no glands

At top of seminal collicus, is located the C shaped urethra, with the utricle underneath. Ejaculatory ducts open on either side of utricle

*cant see uticle and ejaculatory ducts in slide, but need to know them theoretically

on the lateral sides of the collicus are the prostatic sinuses (the end of the C), where the ducts of the glands open into.

Excretory ducts: columnar epith, stains darker than glands

Slide # 68 Seminal Vescicle *H&E

Structures to Identify:

• epithelium
• LP
• 2 muscular layers = circular, longitudinal
• irregular large lumen, with mucosal folds
  
• ductus deferens, if seen

General Info:

• an outgrowth of the ductus deferens
• produce yellowish, viscous fluid,  that contains high amt of fructose,which is energy for sperm
• produce most of the fluid found in semen
• are elongated glands on the posterior side of the bladder
• duct of seminal vesicle combines with ductus deferens to make ejaculatory duct
• vesicles are single tubes whcih are coiled and folded on themselves
• in cross section, look like separate lumens, but it is all one

Secretions contain:

• fructose
• other simple sugars
• amino acids
• ascorbic acids
• prostaglandins (originally discovered in prostate, IMP in inflammatory processes)

Cross section through region of ampulla of DD, so can see both DD and seminal vesicle

Ampulla muscular coat, tinner than rest of DD, and has secretory epithelium

Mucosa

• Epith = columnar or pseudostratified columnar, very invaginated (kinda looks like lumen of gallbladder)
• has mucosal crypts, made by infoldings of the mucosa
• LP
  • smooth m
  • rich in elastic fibers
  • very cell rich
  • goes into the primary mucosal folds
• secondary mucosal folds are the ones that u cant see open up into epithelium (look like closed sacs)

Muscular Layer

• rest on thick layer of smooth m cont w. DD
• smooth musch has inner circular and outer longitudinal layer
• contractions of smooth m. wall during ejaculation pushes substances through ejaculatory duct

Adventia – no peritoneal covering

Embryology  of Seminal Vesicle & Prostate Gland

Genital Duct formation:
Paramesonephric duct starts to develop, but later regresses, due to MIF

Mesonephric duct forms = epididymis, ductus deferens, seminal vesicle, ejaculatory duct, efferent ducts of testis