Male Reproductive Flashcards
function of the scrotum
keep testes away from body core to maintain lower temperature optimum for sperm production
order of sperm travel through testes
- made in seminiferous tubules
- travel through straight tubules
- collect in rete testis
- exit through efferent ducts
- store in head body and tail of epididymis
- travel through vas deferens
- join with seminal vesicle in ejaculatory duct
- run through prostate/prostatic urethra
- membranous urethra
- exit through spongy urethra
how are lobules of seminiferous tubules divided?
tunica albuginea continuous with septa that divide seminiferous tubules into 200-250 lobules
what is tunica vaginalis
an extension of the peritoneum that was picked up on the testes’ descent through abdomen, has parietal and visceral layers (mesothelial sac)
what is tunica albuginea made of
dense irregular connective tissue (is a tough capsule)
what does the mediastinum testis contain
rete testis, vessels, nerves (is a hilum)
what is the mediastinum testis
a posterior thickening of the tunica albuginea
what cells secrete testosterone
leydig or interstitial cells, are clusters within loose vascular connective tissues between seminiferous tubules
3 layers of seminiferous tubules
- innermost stratified seminiferous/germinal epithelium
- middle contractile myoid layer attached to well defined basal lamina
- outermost tinica propria - thin layer fibrous CT
what does the germinal epithelium contain
spermatogenic cells and sertoli cells
what does the tunica propria contain
isolated fibroblasts
what stimulates testosterone production in the leydig cells
LH
describe leydig cells
extensive SER, golgi, lipid droplets (bc steroid secreting), large round pale nuclei, prominent nucleoli, pale acidophilic cytoplasm
where are spermatogenic cells derived
embryonic yolk sac endoderm
how can spermatogenic cells be differentiated
size, nuclear morphology, position in germinal epithelium
chromosomes in stermatogonia
46, diploid 2N
what cell type is present prior to puberty?
spermatogonia ONLY
chromosomes in primary spermatocytes
46, diploid, 2N
what phase of cell division are primary spermatocytes in
frozen in prophase of meisosis I
what is the relationship between primary spermatocytes and sertoli cells and why
primary spermatocytes form tight junctions with sertoli cells to protect from immune system
what cells are rarely seen in the germinal epithelium and why?
secondary spermatocytes, because they rapidly undergo a second meiotic division immediately
chromosomes in secondary spermatocytes
23, haploid, N
chromosomes in spermatid
23, haploid, N
difference between spermatids and spermatozoa
spermatids are variable in size, have dark nuclei and are not in the lumen yet, spermatozoa have a characteristic flattened head and dark nucleus with flagella and are in the lumen
what is unique about the connection of spermatogonia?
they remain attached to form spermatogenic syncytium for some reason
describe the maturation of sperm
- diploid germ cell spermatogonia divide through mitosis and produce a new germ cell plus a committed cell called a primary spermatocyte
- diploid primary spermatocytes undergo 1st meiotic division and become a haploid secondary spermatocyte
- secondary spermatocytes undergo 2nd meiotic division and become spermatids
- spermiogenesis begins, changing spermatids morphologically to be motile spermatozoa
difference between neonatal, fetal, prepubertal, and adult testes
neonatal and infantile testes have 1 layer of spermatogonia with NO lumen; prepubertal testis have a lumen due to increasing testosterone and 1 or 2 layers of spermatogonia; adult testis have large lumen, lots of layers of developing sperm, and have spermatid tails in the lumen
steps of spermiogenesis
- acrosome forms
- centriole migration to posterior pole to form flagellum
- shift of cytoplasm toward flagellum away from acrosome
- migration of mitochondria toward flagellum, wraps around midpiece as mitochondrial sheath
- condensation of nuclear chromatin with nucleus flattening and elongating around midpiece
- cylindrical band of microtubules (manchette) surrounds nucleus
- excess cytoplasm sloughed off into residual bodies
what happens to the residual bodies?
they are phagocytosed by sertoli cells
what is the acrosome?
a large specialized lysosome over the top of the nucleus, containing hydrolytic enzymes that help penetrate zona pellucida and corona radiata
what is a manchette
a cylindrical band of microtubules around the spermatid nucleus
arrangement of microtubules in sperm flagella
9 doublets and 1 central pair
what is normal sperm count?
15 million - 200 million sperm per mL of semen
what is abnormal sperm count?
anything less than 15 million sperm per mL or 39 million sperm per ejaculate
what is oligospermia?
decreased number of sperm
what is teratospermia?
abnormal/mutated sperm morphology
what is asthenospermia?
decreased sperm motility
what do sertoli cells secrete?
androgen-binding protein (ABP), inhibin (fluid for sperm transport), mullerian inhibiting substance
what are the functions of sertoli/sustentacular cells?
- physical and nutritional support of spermatogenic cells
- phagocytosis of residual bodies
- secretion of fluid for sperm transport stimulated by FSH
- secretion of MIS to regress embryonic mullerian ducts
- protection of developing spermatocytes from autoimmune attack
how do sertoli cells form a blood-testis barrier?
they are elongated and branched epithelial cells that extend from basal lamina to lumen of seminiferous tubules that bind to each other through occluding junctions to form a continuous sheath around tubule lumen
what stimulates androgen binding protein and inhibin?
FSH
what is inhibin?
decreases FSH production by pituitary when there is enough
why is the blood testis barrier important?
new sperm specific proteins form on the differentiating cells (primary spermatocyte and on) and may be recognized as non-self antigens by antibodies, this is because this process begins well after immune system development
what makes up the BTB
tight occluding junctions between sertoli cells and continuous capillaries
what does the BTB separate the seminiferous tubules into (layers?)
- basal compartment that houses spermatogonia
2. adluminal compartment that houses everything else
what is special about the adluminal compartment
it is an immunologically privileged site, it is inaccessible to blood bourne substances, except those specifically taken up by sertoli cells and passed through it
what does the duct system require for normal function?
testosterone
what does the duct system entail
from straight tubules in testes through the urethra (there are 2 sets of ducts that empty into a common urethra)
epithelium of straight tubules
spermatogenic cells are replaced by sertoli cells in the initial segment, then replaced by cuboidal epithelium
what are the rete testis lined by
cuboidal epithelium
unique epithelium of efferent ductules
groups of microvili cuboidal cells alternating with groups of ciliated columnar cells
function of the efferent ductules epithelium
the microvili on cuboidal epithelial cells absorb fluid
how is the current made that sweets the sperm to the epididymis
- ciliary action of ciliated columnar cells
2. contraction of thin layer of smooth muscle (myoid layer)
general description of ductus deferens
thick muscular wall, connects epididymis to ejaculatory duct
what makes up the ejaculatory duct
junction of ductus deferens, duct of seminal vesicle, connects to prostatic urethra
function of epididymis
- site of sperm maturation and storage
- water absorption
- enzyme and glycoprotein secretion
- phagocytosis of residual bodies
what lines the ductus epididymis
pseudostratified columnar epithelium with long branched STEREOCILIA, smooth muscle layer underneath this, have small basal cells along basal lamina
how do sperm move through ductus epididymis
underlying smooth muscle layer undergoes peristalsis
what covers the epidiymis
capsule and tunica vaginalis
what lines the mucosal folds of vas deferens
pseudostratified columnar epithelium with sparse stereocilia - secretory and absorptive functions
what makes up the spermatic cord
vas deferens, testicular artery, pampiniform plexus, nerves
defining characteristic of vas deferens
long straight muscular tube with 3 distinct smooth muscle layers, middle circular, inner and outer longitudinal
function of muscle layers of vas deferens
peristaltic contractions during ejaculation
what do the seminal vesicles secrete
fructose, citrate, inositol, prostaglandins, proteins and make up 70% of ejaculate
why do they secrete things
energy for sperm, coagulate sperm upon ejaculation, affect response in female reproductive system
how does the secretion from seminal vesicle enter urethra
2 tubes in each vesicle converge to form a single duct that joins with the ductus deferens on each side to form ejaculatory duct
characteristic of seminal vesicle
honeycomb appearance, underlying muscular layer that contracts during ejaculation, highly folded and branched mucosa with simple or pseudostratified columnar epithelium
what are seminal vesicles?
2 highly coiled outgrowths of ductus deferens
what lines the seminal vesicles
pseudostratified columnar epithelium
what does the prostate gland consist of?
compound tubuloalveolar glands arranged in 3 concentric groups whose ducts empty independently into the urethra
what does the prostate gland secrete?
PSA, citric acid, acid phosphatase, amylase, fibrinolysin, lipids
what is characteristic of the prostate and what is it
corpora amylacea, glycoprotein concretions in lumen of prostate, increase in number, size and calcification with age
what covers the prostate
a fibroelastic CT capsule with smooth muscle that contracts during ejaculation
what makes up prostatic epithelium
folded mucosa of cuboidal, columnar, and pseudostratified columnar epithelium
where is peripheral zone of prostate
outer area close to rectum, posterior under the ejaculatory duct, and anterior under half
what is the most common site of prostate cancer?
peripheral zone
what is the most common site of BPH?
transition/periurethral zone
where is central zone>
surrounding seminal vesicle toward urethra
where is transition/periurethral zone
innermost, surrounds upper part of urethra
what makes up the tubuloalveolar lobe?
- secretory/glandular epithelium made of simple columnar or pseudostratified columnar
- lamina propria and smooth muscle covers each lobe
- corpus amylaceum
what are bulbourethral glands?
cowper’s glands, small paired glands in the UG diaphragm (deep space)
where do cowper glands empty
proximal part of penile urethra
what do cowper glands secrete, and what secretes them, and why
alkaline mucus, secreted by simple columnar epithelium, to coat and lubricate the urethral lining during erection and ejaculation
what lines the prostatic segment of the urethra
transitional epithelium bc connects directly with the bladder
where is prostatic segment of urethra
exits neck of the bladder, receives prostatic and ejaculatory ducts
what lines membranous segment of urethra
pseudostratified columnar epithelium
what encircles membranous urethra
UG diaphragm, forms a voluntary external sphincter
where is cavernous segment
passes through corpus spongiosum
what lines cavernous segment of urethra
pseudostratified columnar epithelium, CHANGES TO STRATIFIED SQUAMOUS AT THE END
what empties into the cavernous segment of urethra?
glands of littre empty mucus secretions into the lumen
general description of erectile tissue
- irregular networks of fibrous CT (tunica albuginea)
- supporting framework of smooth muscle fibers
- abundant interconnected vascular sinuses (fill with blood, lined with endothelial cells)
what surrounds the corpus cavernosum and spongiosum?
dense fibrous tunica albuginea
physiology of erection
parasympathetic stimulation: dilation of helicine arteries, fills cavernous spaces which press against veins against the tunica albuginea, blocking outflow of blood = maintains rigidity
sympathetic stimulation: to constrict helicine arteries to decrease blood flow, lower pressure, allow veins to open and drain (ejaculate)
flaccid state
contracted smooth muscle limits inflow of blood into cavernous spaces, venous outflow is high to prevent cavernous space dilation
erect state
parasympathetic system relaxes smooth muscle, allows increased inflow of blood, dilated cavernous spaces compress venules against tunica albuginea to decrease venous outflow
