Straight Tubule --> Ejaculatory Duct and Hormonal Regulation

Question 1

what nuclei make GnRH

Answer 1

arcuate and preoptic

Question 2

each lobule in testis has how many convoluted seminiferous tubules

Answer 2

1-4

Question 3

intratesticular ducts

Answer 3

the straight tubules and rete testis that connect the seminiferous tubules to the ductus epididymis

Question 4

GnRH –> LH/FSH –> ??

Answer 4

LH = regulation of testosterone production by Leydig cells

FSH = proliferation and seminiferous tubule growth

Question 5

FSH function in sertoli cells

Answer 5

initiation of spermatogenesis in puberty done by FSH secreted growth factors

signals upregulation of ABP by sertoli cells

development of the blood testis barrier

Question 6

inhibin B

Answer 6

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

Question 7

testosterone feedback

Answer 7

(+) on sertoli cells (with FSH) to initiate spermatogenesis etc

(-) on anterior pituitary and hypothalamus

Question 8

estradiol

Answer 8

release from sertoli cells is stimulated by FSH

(-) feedback on Leydig cells

Question 9

leydig cells = ? cells

sertoli cells = ? cells

Answer 9

theca

granulosa

Question 10

androgen –> estrogen conversion system in testis

Answer 10

1. leydig cells produce androgens
2. travel through the basement membrane into the seminiferous epithelium
3. sertoli cells convert androgen to estradiol

Question 11

3 forms of testosterone

Answer 11

1. bound to albumin loosely (50%) bioavailable
2. tightly bound to sex hormone binding globulin (SHBG) = 44% bio-inactive
3. free (2-3%) bioavailable

Question 12

fate of testosterone once reaches target cells

Answer 12

remain testosterone

converted to estrogen

converted to DHT

Question 13

5-alpha reductase

Answer 13

testosterone –> DHT

DHT = involved in creation of external genitalia

Question 14

peripheral testosterone

Answer 14

responsible for sexual differentiation

Question 15

intratesticular testosterone

Answer 15

high local levels in the testis is needed for spermatogenesis

Question 16

testosterone receptor

Answer 16

androgen receptor

all forms of testosterone bind to it

Question 17

masculinization of the brain is regulated by what hormone

Answer 17

estradiol, which was converted from testosterone

Question 18

fetal testosterone

Answer 18

testes stimulated by placental hCG to make moderate amounts of T

important for development of the fetus

Question 19

puberty testosterone levels

Answer 19

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

Question 20

testosterone at age 40

Answer 20

start going down slightly and SHBG binding increases

Question 21

andropause

Answer 21

decreased sperm production, fatigue, depression, decreased erectile dysfunction

Question 22

hypergonadism

Answer 22

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

Question 23

hypogonadism

Answer 23

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’

Question 24

challenge test for hypogonatropic disease

Answer 24

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

Question 25

straight tubule of testis

Answer 25

tubuli recti end of seminiferous tubule feed into rete testes early = lined by sertoli cells ONLY late = simple cuboidal epithelium

Question 26

rete testis

Answer 26

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

Question 27

venous epithelium of testes

Answer 27

more acidophilic than rete testis lumen = blood

Question 28

excurrent ducts are what...

Answer 28

efferent ductules ductus epididymis vas deferens ejaculatory duct

Question 29

efferent ductules

Answer 29

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

Question 30

epididymus

Answer 30

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

Question 31

histology of ductus epididymus

Answer 31

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

Question 32

vas deferens

Answer 32

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

Question 33

histology of vas deferens

Answer 33

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

Question 34

histological differences between vas deferens and oviduct

Answer 34

vas deferens = pseudostratified epithelium and NO mucosal folds oviduct = non-ciliated and ciliated simple columnar cells (Peg cells for secretion) and real mucosal folds

Question 35

vas deferens vs, ureter histologically

Answer 35

both have transitional epithelium with dome shaped cells SmM layers are more tightly packed in vas deferens

Question 36

ejaculatory duct

Answer 36

connects the end of the vas deferens to the urethra through prostate glands pseudostratified columnar does not have muscularis

Question 37

straight tubules 1. cell types = 2. muscle/tissue = 3. function =

Answer 37

1. early = sertoli late = simple cuboidal 2. CT 3. sperm transport

Question 38

rete testes 1. cell types = 2. muscle/tissue = 3. function =

Answer 38

1. simple cuboidal with microvilli and cilia 2. dense CT of mediastinum 3. sperm transport = channels with sperm from all seminiferous tubules

Question 39

efferent ductules 1. cell types = 2. muscle/tissue = 3. function =

Answer 39

1. wavy pseudostratified columnar - short cells = microvilli and long cells = cilia 2. thin SmM circular and loose CT 3. absorb most fluid and sperm transport

Question 40

ductus epididymis 1. cell types = 2. muscle/tissue = 3. function =

Answer 40

1. pseudostratified columnar = basal cells + stereociliated cells 2. SmM at head and body (1 circular)...tail = 3 layers 3. absorb fluid, sperm maturation and storage; expel sperm at ejaculation

Question 41

vas deferens 1. cell types = 2. muscle/tissue = 3. function =

Answer 41

1. stereociliated pseudostratified columnar 2. fibroelastic lamina propria and 3 layers of SmM 3. sperm transport and absorb fluid

Question 42

ejaculatory duct 1. cell types = 2. muscle/tissue = 3. function =

Answer 42

1. pseudostratified and simple columnar 2. fibroelastic and prostate SmM 3. absorb most fluid and sperm transport