Lecture 6 & 8 - Spermatogenesis

Question 1

Process of descent of testis - what hormones involved

Answer 1

In abdominal cavity to inguinal ring - amh
in inguinal ring to scrotum - testosterone
-also the ligament gubernaculum will pull them down

Question 2

Cryptorchidism

Answer 2

incomplete - gets lodged in inguinal ring

maldescent - in wrong place e.g abdominal cavity

• normally self corrects
• can do surgery if not
• can cause infertility due to the difference in temperature

Question 3

Spermatogonia, sertoli, leydig and myoid cells - function

junctional complex

Answer 3

spermatogonia - on the outside of the basement membrane and move towards the lumen when becoming primary spermatocytes –> spermatids

sertoli - epithelial, support
leydig - interstitial cells - produce the androgen - testosterone

junctional complex - is in sertoli cells - tight junction
-separates spermatogonia from spermatids (dont want immune system to react to these cells)

myofribrobalsts - sit on outside of tutbule can sqeeuze so sperm goes down efferent ducts

Question 4

Spermatogenesis - 3 different stages

Answer 4

Spermatocytogenesis - mitosis
Meisos
Spermiogenesis

Question 5

Is testi development and maintenance dependent on pituitary ?

Answer 5

Yes - hypothalamus controls pituitary controls conads.
When you remove hypothalmaus, at any stage then get a decrease in testis weight
-this shows it is necessary

Question 6

Is pituitary function dependent on testis?

Answer 6

Yes

• remove testis, dont have as much testosterone for negative feedback of fsh and lh
• see an increase in fsh and lh levels

Question 7

What happens if add exogenous testosterone?

Answer 7

Will get decrease in lh and fsh due to the negative feedback testosterone has on these

Question 8

Relationship between LH and T

Answer 8

LH - drives testosterone production

can see that similar pulsitile pattern, when LH increases, testorone follows shortly after

Question 9

Hormonal control of spermatogenesis

Answer 9

pg 33

Question 10

effect of T/DHT on spermatogenesis

Answer 10

1. necessary for meiosis
2. necessary for spermatid maturation (need more htan meiosis)
3. stimualte ABP

-can add testosterone after remove pituitary adn still get sperm maturaiton

Question 11

hypogonadal man

Answer 11

• testis not functioning
• LH and fsh increase (due to less negative feedback)
• if give T then these levels drop

Question 12

What happens to the peaks of LH when you add testosterone? estrogen

Answer 12

the peaks decrease, reduce frequency

-if give estrogen then just reduce peaks but dont change frequency

Question 13

why is estrogen important in males?

Answer 13

• important for negative feedback of T
• T is converted to E in fatty tissues
• also can enhance the action of androgens
• rat study
• without estrogen, spermatogenesis was interepetued and sperm could not fully mature - need estrogen as well as T for spermatogeneisis

female - follicules developed and never progressed to ovulaition, strated to form seminifirous tuberlies (turn ovary into testis)

Question 14

what is a good test for testicular disorders?

Answer 14

sperm count and fsh measurement

Question 15

• Where does sperm maturation occur?

Answer 15

epididymis (after released from seminifious tubules)

• changes - cytoplasm, structure - increase stifness and swiming behaviour
• concentraton increases due to absorption of fluid - Depenedent on estrogen

Question 16

Seminal fluid - where from , what does it contain?

Answer 16

From - seminal vesicles, prostate, epididimis

Contains - fructosenad prostaglandins

Question 17

• Ejaculation
  Emission and expulsion phase
  -what muscle, and nervous system

Answer 17

Emission - emission of semun and ducts by contraction of smooth muscle, sympathetic (L1- ejaculation center)

Expulsion - contraction of somatic muscles - (corpra cavernosa, corpus spongiosum) parasympathehtic control (S2-erection center)

1. Sensory input (touch, vision ect.) sensed by S2 erection center nervous system
2. vasodilation of arteries - erection
3. Ejaculation center (L1 - sympathetic) activated, and will then prepare secretions from vas deferens, prostate, ect. - smooth muscle contraction (emission phase)
4. Explusion phase - by S2 - somatic muscle contract for ejaculation

Question 18

• Assessment of male infertility

what else is associated

Answer 18

• volume, sperm count, motility, morphology ect.
• if more than 3 are bad,then more likely fertilization will not occur

-also is affected by testosterone levels, frequency of emission, temperature (-2.2C)