Seminal vesicle and Prostate Flashcards
seminal vesicles location
paired, elongated, highly coiled tubular glands located on the posterior wall of the urinary bladder
sminal vesicle function
secrete and store seminal fluid
secretions = 60-70% of seminal fluid; are expelled in the 2nd fraction of the ejaculate to wash the sperm out of the ejac duct and urethra
also dilute the thick mass of sperm to enable them to develop motility
seminal fluid
alkaline
helps neutralize the acidic vagina
principal constituent of seminal secretion
fructose
other components of seminal fluid besides fructose
prostaglandins - believed to stimulate contractions of the SmM in both the male and female reproductive tracts
- thereby transport sperm from their storage to site of fertilization
fibrinogen = precursor of fibrin which forms the meshwork of a clot that holds the semen in the deeper regions of the vagina
lumen of seminal vesicles
one
large
stores the fluid secretion (but not spermatozoa) between ejaculations
mucosa of seminal vesicle
arranged into convoluted folds to significantly increase the secretory surface area
pseudostratified columnar with tall, non-ciliated columnar cells (secretory) and short round basal cells
also the presence of simple columnar
CT lamina propria with elastic fibers
muscularis of seminal vesicle
inner circular and outer longitudinal
contraction during ejaculation
secretory function of seminal vesicle is under the control of what hormone
testosterone
differences between seminal vesicle and oviduct
oviduct = columnar cells are ciliated
same between seminal vesicle and oviduct
tubular structure with branching mucosal folds in lumen
inner circular and out long muscle walls
prostate gland location
surrounds the urethra just below the urinary bladder, and can be felt during a rectal exam
prostate gland function
general
largest accessory sex organ in males
secretes and stores a thin, milky, and slightly basic fluid
25-30% of seminal fluid
prostatic fluid
1st ejaculate fraction with most of the spermatozoa
neutralizes vagina
provides clotting enzymes and fibrinolysin
clotting enzymes of prostatic fluid
act on fibrinogen from the seminal vesicles to produce fibrin
which clots the semen to help keep the ejaculate sperm in deeper regions of the vagina
fibrinolysin of protstatic fluid
clot is formed
15-30min later the seminal clot is broken down by fibribolysin (fibrin-degrading enzyme)
to release motile sperm within female tract
prostate-specific antigen (PSA)
serine protease released from prostatic epithelium cells
important tumor marker
normal = mainly released into prostatic secretion - helps liquefy coagulated semen for slow release of sperm after ejaculation; small amounts leak into blood
prostate cancer = large amounts of PSA are produced and misdirected into circulation
high PSA levels in plasma
associated with prostate cancer
or benign prostatitis or BPH
prostatic acid phosphatase (PAP)
made by prostatic epithelium
elevated serum levels are found in patients with metastatic prostate cancer
exocrine prostate
compound tubuloalveolar exocrine glands (30-50)
empty into 15-25 independent excurrent ducts
these ducts open into urethra
glands are embedded into a dense fibromuscular stroma which mainly consists of SmM separated by dense CT
prostatic glandular epithelium
generally simple columnar
changes to transitional epithelium near the openings of the ducts into urethra
5alpha-reductase in prostate
testosterone and adrenal androgens are converted to DHT
DHT stimulates the growth of normal prostatic epithelium and proliferation and growth of BPH and prostate cancer
prostatic concretions (corpora amylacea)
characteristic feature of prostate
in the alveoli
appear in sections as concentric lamellated bodies
- formed by precipitations of secretory material around cell fragments
number increases with age
prostate vs lactating mammary gland
prostate
- indistinct lobules
- stroma prominently surrounds the gland
- SmM in stroma
- lamellated prostatic concretions
mammary
- distinct lobules
- thin CT septae separating lobules
- no SmM in stroma
- myoepithelial cell contraction helps milk ejection
both
- compound glands embedded in a dense fibrous stroma
- secretory epithelial cells
four zones of prostate
transitional
periurethral
central
peripheral
peripheral zone of prostate
posterior and lateral parts, surrounds the distal urethra
most susceptible to inflammation
64% of cancers are here
palpable on rectal exam
central zone of prostate
surrounds ejaculatory duct
resistance to carcinoma and inflammation
transitional zone
surrounds the proximal prostatic urethra
34% of cancers
responsible for benign prostatic hyperplasia (BPH)
- outgrowth of both glandular eptihelial and stromal cell compartments
- formation of nodular masses
- can compress the prostatic urethra, causing difficult urination
periurethral zone of prostate
in later stage of BPH, this zone may undergo pathologic growth….but mainly from the stronal components
- also causes increased urethral compression and retention of urine in the bladder
fibromuscular stroma of prostate
occupies anterior surface of the prostate gland…anterior to urethra
composed of dense irregular connective tissue with large amount of SmM fibers
Prostate cancer
most common non-skin cancer in men in USA
incidence increases with age
usually develop in the peripheral zone, does not impinge on the urethra to produce symptoms
diagnose by using the PSA test usually…but also can do a biopsy
treatment of prostate cancer
surgery
radiation therapy
hormonal therapy
- reduce circulating androgens by performing an orchiectomy (removal of testis) or by administration of GnRH agonists or antagonists
- block activity of androgen receptor by androgen receptor angtagonist
- almost always lead to recurrence - major cause of prostate cancer mortality
orchiectomy
treatment of prostate cancer
reduces T and DHT
but significant rises in LH and FSH
GnRH antagonists
treatment of prostate cancer
inhibit GnRH receptor and immediately stop LH secretion and suppress T level
sustained suppression in LH, testosterone, DHT, and FSH
GnRH agonists
treatment of prostate cancer
produce an initial surge in LH, FSH, T, and DHT
continuous pituitary stimulation down regulates and desensitizes GnRH receptor
–> leads to eventual decrease in LH, FSH and T and DHT
Melatonin regulation of GnRH release
pre puberty –> puberty
melatonin is secreted by pineal gland at night at a steady rate after age of 3 months
inhibits GnRH pulse generator (functioning since birth)
throughout childhood, the GnRH axis remains inhibited
at puberty….body mass increases, leading to decrease concentrations of melatonin –> GnRH generator is activated
Cowper’s (bulbourethral) gland
size of a pea
function:
- secretion of clear, mucus-like, pre-seminal fluid (pre-ejaculate) to lubricate the urethra
- neutralizes acidic traces of urine in urethra and helps flush out any residual urine or foreign matter
Semen
10% sperm
90% seminal plasma
pre-ejaculate = bulbourethral gland secretion
first fraction = spermatozoa and prostate secretion
second fraction = seminal vesicle secretion
Summary of all functions of the seminal fluid
- neutralize acidic urethra and vagina
- providing energy source for sperm
- forming seminal clot
- regulating sperm motility
- helping transport sperm
