LEC39: Microstructure of Male Reproductive System Flashcards
how much semen & sperm does avg man have / ejaculate
3.5 mL semen, each ejaculate has 200-300 million sperm
components of male reproductive system
testes, genital ducts (paired), glands (exocrine), penis
parts of (paired) genital ducts
efferent ductules (ductuli efferentes)
epididymis
vas deferens (ductus deferens)
ejaculatory ducts
(exocrine) glands of male reproductive system
seminal vesicles (2, paired)
prostate (1)
bulbourethral glands of Cowper (paired)
efferent ductules function
sperm passage
epididymis function
sperm storage, maturation
vas deferens function
where sperm pass through > ejaculatory ducts
where are glands of cowpoer
urogenital diaphragm
what forms capsule for testes
tunica albuginea
what divides testes into lobules, how many lobules are there?
septa
250 lobules
what is within lobules?
1-4 seminiferous tubules / lobule, avg=2
each 50 cm long
combined length of seminiferous tubules in 1 testis
250m long
parts of epididymis
head, body, tail
what contains the rete testis
mediastinum testis
what is between seminiferous tubules in TV sections
interstitial tissue, where testes produce hormones (endocrine fxn happens here)
what surrounds seminiferous tubules
interstitial tissue
basement membrane
types of cells in seminiferous epithelium
1) spermatogenic cells/germ cells, contain all phase of germ cell, from spermatogonia thru maturing sperm
2) sertoli cells/somatic cells
3) basement membrane
3 types of spermatogonia, what differences mean
1) dark type A
2) pale type A
3) type B
based on staining characteristic of nucleus - if stains dark/pain
3 processes of spermatogenesis
1) spermatocytogenesis
2) meiosis
3) spermiogenesis
what does spermatocytoenesis consist of?
spermatogonia > 1o spermatocytes
what does meiosis of spermatogenesis consist of?
1o spermatocytes (2N) thru meiosis I > 2o spermatocytes (1N) thru meiosis II > spermatids
what does spermiogenesis consist of?
spermatids (1N) > sperm (1N)
spermatocytogenesis process
1) dark type A cell undergoes mitosis, becomes pale type A
2) pale type A becomes 1o spermatocyte; that undergoes prophase of meiosis I
what happens to 1o spermatocyte
for 22 days, it undergoes meiosis I
when does 1o spermatocyte become 2o spermatocyte
at end of meiosis I
what does 2o spermatocyte undergo
meiosis II; spends 8 hours at interphase of meiosis II before completing & becoming spermatid
how long does entire process of spermatogonia to sperm take
64 days
what is spermiogenesis
transformation of spermatids into sperm
acrosome develops
what is process of acrosome development, where does it come from?
from golgi apparatus’s hydrolitic enzymes
acrosomal part of sperm develops from granule > vesicle > cap > full acrosome cap structure on upper part of sperm nucleus
how long does sperm spend in epididymis
1-12 days
what happens during spermiogenesis
1) acrosome develops
2) flagellum develops
3) mitochondria aid sperm tail development
what is flagellum derived from, and what is its main structural component?
from 1 of 2 centrioles
contains microtubule arrangement associated with cilia
length of sperm head, tail
head: 5 micron
tail: 60 micron
what structure in center of sperm tail is important, why
cilium
use mitochondria for movement
surrounded by CT
how does sperm move in seminiferous tubule?
moves along genital duct via testicular folds down the duct, as it does not have head/tail yet
when can sperm move alone?
once mature, capacitated, in epididymis/oviduct
structure of sperm tail
from head end > end of tail
middle piece: mitochondria, dense fibers
principal piece: fibrous sheath
end piece: cilium
what does acrosome contain for digestion
lysosomal enzymes
what color do lysosomal enzymes of acrosome stain?
red
nucleus = yellow
what does zona pellucida express?
3 glycoproteins:
ZP1, ZP2, ZP3
how does sperm penetrate ovum?
acrosomal enzyme reaction; hyaluronidase penetrates corona radiata; sperm head binds to zona pellucida; sperm binds to ZP3 of zona pellucida, enters ovum
what kind of cells are sertoli cells?
somatic cells
what does sertoli cell contact?
base- basement membrane
extends up into seminiferous tubule
what is the nature of sertoli cells?
constantly changing
can move from lower > upper part of tubule
sertoli cell functions?
1) supportive: structural support, nutrients, waste material transport to blood/lymph for spermatogenic cells
2) phagocytosis: of residual bodies, degenerative spermatogenic cells
3) secretion: androgen-binding protein which binds testosterone; inhibin which suppressess FSH secretion; testicular fluid
4) blood-testis barrier
what do sertoli cells secrete?
1) androgen-binding protein: binds testosterone
2) inhibin: suppresses FSH secretion
3) testicular fluid
what connects adjacent sertoli cells? what is result?
tight junctions between adjacent sertoli cells’ cell processes
this forms blood-testis barrier
what does blood-testis barrier do?
divides seminiferous tubules into
1) basal compartment- below tight junction, houses spermatogonia
2) adluminal compartment- above tight junction, contains 1o, 2o spermatocytes, maturing sperm
what is morphological evidence of blood-testis barrier?
lanthanum nitrate (e- dense material) cannot enter adluminal compartment when injected into blood stream
blood-testis barrier functions
1) restricts passage of large MW chemicals, mutagens, toxic drugs, antibodies from blood circulation > adluminal compartment
2) protects maturing sperm in adluminal compartment against blood born noxious agents
when does blood-testis barrier form
puberty
is there movement within blood-testis barrier?
yes, can open/close to allow sperm to move up from basal > adluminal compartment
what is between seminiferous tubules
interstitial tissue
interstitial tissue function?
endocrine tissue of the testes
what does interstitial tissue contain?
leydig cells
what do leydig cells do?
secrete testosterone, under LH
what factors affect spermatogenesis?
1) temperature
2) x-ray irradiation
3) malnutrition
4) alcoholism
5) cadmium
6) hormones
what is cryptorchidism?
undescended testis in body cavity
cannot make sperm because temperature (37.8) in body cavity
what doesn’t effect sertoli cells and leydig cells, and why?
temperature and x-rays
because they are somatic cells
ex: with cryptorchidism, testis cannot make sperm but do produce testosterone from leydig cells
hormonal control of the MRS
go over this
where do seminiferous tubules end?
rete testis, in mediastinum in posterior part of testis
where does fluid from rete testis go?
efferent ductules > epididymis
how long is epididymis?
4-6m long; coils into 5 cm
what is efferent ductule surrounded by
smooth muscle
what does lumen of epididymis contain
clusters of sperm, cell debris suspended in testicular fluid
what happens while sperm are in epididymis?
1-12 days undergo progressive maturation acquire motility DO NOT CAPACITATE absorption, secretion phagocytosis of degenerating sperm
cell type of epididymis epithelium?
pseudostratified columnar epithelium w/ stereocilia
what are stereocilia
modified long microvilli
lack motility
increase surface absorptive area of epididymis
cell type of rete testis?
cuboidal with cilia
move testicular fluid along tubule
cell type of efferent ductule?
tall ciliated columnar cells: move sperm to epididymis
short non-ciliated cells: reabsorb some of testicular fluid
duct surrounded by smooth muscle
how does TV section of epididymis appear and why?
appears as multiple transverse sections of same duct
because duct is highly coiled
layers of vas deferens?
3 layers of smooth muscle:
1) outer longitudinal
2) circular
3) intermedial
cell type of vas deferens?
pseudostratified columnar epithelium
are there stereocilia in vas deferens?
beginning part where comes from epididymis, perhaps, but then disappear down tube
what is ampulla
forms diverticulum from vas deferens to form seminal vesicle
what empties into prostate gland
ejaculatory duct from seminal vesicle & vas deferens > parenchyma of prostate
how long is seminal vesicle?
15 cm; coils on itself to be 5-6 cm
what is seminal vesicle derived from?
vas deferens
what is structure of seminal vesicle?
highly folded mucosa surrounded by 2 layers of smooth muscle
epithelial cell type of seminal vesicle?
pseudostratified columnar or simple cuboidal-columnar epithelium
depends on age, hormones
how much of seminal fluid do seminal vesicles secrete
70%
what does stroma of seminal vesicle have?
smooth muscle, elastic fibers
what is composition of seminal vesicle secretion?
thick, creamy, yellowish, alkaline fluid; substances modify sperm activity
1) fructose
2) citric acid & ascorbid acid
3) fibrinogen
4) prostaglandins
5) yellow lipofuscin pigments
fructose function in seminal vesicle secretion?
energy source for sperm motility
citric and ascorbic acid function in seminal vesicle secretion?
vitamin C
fibrinogen function in seminal vesicle secretion?
coagulates semen after ejaculation
prostaglandins function in seminal vesicle secretion?
stimulate activity in FR tract
yellow lipofuscin pigments function in seminal vesicle secretion?
pale yellow color of semen
fluid flow through prostate?
prostate glands > ducts > prostatic urethra
what surrounds prostate?
thin fibrous CT capsule
prostate zones, % of prostate they occupy?
transition zone: surrounds urethra (5%)
central zone: encircles ejaculatory ducts (20%)
peripheral zone (70%)
what is stroma of prostate structure?
fibromuscular
corpora amylacae
calcified glycoprotein
number increases with age
prostatic concretions
prostatic glands cell type
pseudostratified columnar epithelium
stroma cell types
collagen fibers
smooth muscle cells
stromal cells
what is benign prostatic hyperplasia
increase in number, size of prostatic glands
increase in amt of stroma
hypertrophy of smooth muscle cells, increased activity of STROMAL CELLS
>4-5cm rather than <4 cm normal prostate
where does BPH occur?
transition zone
where does prostate cancer occur?
peripheral zone
how much of seminal fluid does prostate secretion make up?
30%
what does prostate secretion contain?
thin, milky colored fluid:
1) fibrinolysin- liquifies solidified semen
2) proteases, acid phosphatase
3) prostate-specific antigen (PSA), a serine protease - tumor marker
4) citric acid, zinc, electrolytes, lipids
what used to be a prostate cancer marker, and no longer definitely is?
psa - prostate-specific antigen
serine-protease tumor marker
psa= 0-4 mg/ml
what do bulboureathral glands secrete
mucus-like substance that precedes emission of semen; has lubrication function for passage of semen along urethra
1) galactose
2) sialic acid
where are bulbourethral glands?
in skeletal muscle of urogenital diaphragm
