Straight Tubule --> Ejaculatory Duct and Hormonal Regulation Flashcards
what nuclei make GnRH
arcuate and preoptic
each lobule in testis has how many convoluted seminiferous tubules
1-4
intratesticular ducts
the straight tubules and rete testis that connect the seminiferous tubules to the ductus epididymis
GnRH –> LH/FSH –> ??
LH = regulation of testosterone production by Leydig cells
FSH = proliferation and seminiferous tubule growth
FSH function in sertoli cells
initiation of spermatogenesis in puberty done by FSH secreted growth factors
signals upregulation of ABP by sertoli cells
development of the blood testis barrier
inhibin B
levels correlate with total sperm count and testicular volume
can be used as an index of spermatogenesis
negative feedback to anterior pituitary release of LH and FSH
testosterone feedback
(+) on sertoli cells (with FSH) to initiate spermatogenesis etc
(-) on anterior pituitary and hypothalamus
estradiol
release from sertoli cells is stimulated by FSH
(-) feedback on Leydig cells
leydig cells = ? cells
sertoli cells = ? cells
theca
granulosa
androgen –> estrogen conversion system in testis
- leydig cells produce androgens
- travel through the basement membrane into the seminiferous epithelium
- sertoli cells convert androgen to estradiol
3 forms of testosterone
- bound to albumin loosely (50%) bioavailable
- tightly bound to sex hormone binding globulin (SHBG) = 44% bio-inactive
- free (2-3%) bioavailable
fate of testosterone once reaches target cells
remain testosterone
converted to estrogen
converted to DHT
5-alpha reductase
testosterone –> DHT
DHT = involved in creation of external genitalia
peripheral testosterone
responsible for sexual differentiation
intratesticular testosterone
high local levels in the testis is needed for spermatogenesis
testosterone receptor
androgen receptor
all forms of testosterone bind to it
masculinization of the brain is regulated by what hormone
estradiol, which was converted from testosterone
fetal testosterone
testes stimulated by placental hCG to make moderate amounts of T
important for development of the fetus
puberty testosterone levels
pulsatile release of GnRH begins
leads to increase in T
essentially no testosterone is made before puberty
during puberty = LH levels increase –> increase testosterone
initially during sleep
later throughout the day
testosterone at age 40
start going down slightly and SHBG binding increases
andropause
decreased sperm production, fatigue, depression, decreased erectile dysfunction
hypergonadism
too much androgen before puberty
causing early puberty properties
causes:
- hypothalamic tumors
- activating mutations in LH receptor
- CAH
- androgen-producing tumors
- pinealoma
all of these would lead to HIGH testosterone levels
increased testosterone –> more negative feedback so low LH
hypogonadism
decreased androgen production
2 possible causes
A. hyper-gonadotropic (Primary) = testicular dysfunction in presence of elevated gonadotropin levels
- issue with leydig cells
- body overproduces GnRH, and LH since low testosterone
B. hypo-gonadotropic (secondary) = issue is in ht hypothalamus OR pituitary
- still low testosterone
- differentiate between origin of issue with ‘challenge test’
challenge test for hypogonatropic disease
give patient GnRH and look at LH/T levels
if hypothalamus= = LH and T will go up
if pituitary = LH and T will be low
straight tubule of testis
tubuli recti
end of seminiferous tubule
feed into rete testes
early = lined by sertoli cells ONLY
late = simple cuboidal epithelium
rete testis
connections between different lobules of the testes
exist in the mediastinum testes
cuboidal or low columnar epithelium
more basophilc than the venous plexus epithelium
lumen = sperm
venous epithelium of testes
more acidophilic than rete testis
lumen = blood
excurrent ducts are what…
efferent ductules
ductus epididymis
vas deferens
ejaculatory duct
efferent ductules
move sperm towards the epididymis and reabsorbs fluid secreted by the sertoli cells of the seminiferous tubules
pseudostratified columnar
- alternating tall and short cells (wavy outline)
- tall = cilia –> movement of sperm
- short = villi –> absorption of fluid
single layer of SmM interspersed between elastic fibers - helps in sperm transport
epididymus
3 sections
head = efferent ductules with wavy outline of lumen
- single SmM layer that contracts spontaneously
body = ductus epididymus = where spermatozoa mature and gain the ability to move and fertilize (has straighter lumen)
- inhibitory proteins stop actual movement here though..
- single SmM layer that contracts spontaneously
tail = duct of the epididymis = where sperm is stored
- 3 layers of SmM that does not contract spontaneously
- inner and outer long
middle circular
- needs neurostimulation
histology of ductus epididymus
pseudostratified columnar (not alternating tall and short)
principle cells = long columnar with stereocilia (absorption)
basal cells
sperm in lumen
larger lumen than efferent ductules = how can tell them apart
vas deferens
continuation of the tail of the epididymis that enters the abdomen as part of the spermatic cord
function = strong contractions in response to neurostimulation to expel the sperm into the ejac duct
histology of vas deferens
lumen = longitudinal folds (NOT mucosal folds)
mucosa = similar to the mucosa of the ductus epididymis
- but columnar cells aren’t as tall and dont ahve as many cilia (so not called principle cells anymore)
lamina propria = loose CT with elastic fibers
muscularis = THICK because it is also contracting in response to neurostimulation for ejaculation
- 3 layers = long, circular, long
adventitia = mixed with CT of the spermatic cord
histological differences between vas deferens and oviduct
vas deferens = pseudostratified epithelium and NO mucosal folds
oviduct = non-ciliated and ciliated simple columnar cells (Peg cells for secretion) and real mucosal folds
vas deferens vs, ureter histologically
both have transitional epithelium with dome shaped cells
SmM layers are more tightly packed in vas deferens
ejaculatory duct
connects the end of the vas deferens to the urethra through prostate glands
pseudostratified columnar
does not have muscularis
straight tubules
- cell types =
- muscle/tissue =
- function =
- early = sertoli
late = simple cuboidal - CT
- sperm transport
rete testes
- cell types =
- muscle/tissue =
- function =
- simple cuboidal with microvilli and cilia
- dense CT of mediastinum
- sperm transport = channels with sperm from all seminiferous tubules
efferent ductules
- cell types =
- muscle/tissue =
- function =
- wavy pseudostratified columnar - short cells = microvilli and long cells = cilia
- thin SmM circular and loose CT
- absorb most fluid and sperm transport
ductus epididymis
- cell types =
- muscle/tissue =
- function =
- pseudostratified columnar = basal cells + stereociliated cells
- SmM at head and body (1 circular)…tail = 3 layers
- absorb fluid, sperm maturation and storage; expel sperm at ejaculation
vas deferens
- cell types =
- muscle/tissue =
- function =
- stereociliated pseudostratified columnar
- fibroelastic lamina propria and 3 layers of SmM
- sperm transport and absorb fluid
ejaculatory duct
- cell types =
- muscle/tissue =
- function =
- pseudostratified and simple columnar
- fibroelastic and prostate SmM
- absorb most fluid and sperm transport
