Testis Development

Question 1

Describe the development of fetal testis

Answer 1

On anki

Question 2

What are the 2 types of staining used for testis histology

Answer 2

Haematoxylin & immunohistochemistry staining

Question 3

In immunohistochemisrty staining, what colour do the gonocytes and what colour do the Sertoli cells stain?

Answer 3

Gono red & sertoli green

Question 4

What gene induces Sertoli cell differentiation?

Answer 4

SRY

Question 5

What do the Sertoli cells form? And what do they secrete?

Answer 5

Sex cords and tubules
Secrete Dhaka and PDGF-A to induce Leydig cell formation

Question 6

The leydig cell
-found where
-2 populations of it

Answer 6

Found ininterstitial tissue between tubules
-2 populations in mammal; foetal/neonatal & adult

Question 7

What is the function of the leydig cell? What hormone stimulates its release?

Answer 7

to make androgens, primarily testosterone, under the control of LH release from the anterior pituitary
Also makes INSL3

LH stimulate its release

Question 8

What is testosterone and INSL3 essential for?

Answer 8

Testis descent

Question 9

What are the 2 time peaks of androgen production in the leydig cell and what are they necessary for?

Answer 9

1. In fetus (ensures masculinisation)
2. In adult (necessary for fertility, sex drive and maintenance of secondary sex characteristics)

Question 10

What is INSL3

Answer 10

Insulin-like growth factor

Question 11

The Sertoli cell- controlled by…

Answer 11

Controlled by FSH release from the anterior pituitary and androgen release from Leydig cells

Question 12

Name the three cells found in testis

Answer 12

Leydig cell
Sertoli cell
Peritubular myoid

Question 13

Testis descent occurs before or after birth

Answer 13

Before birth

Question 14

What is androgens role in testis descent?

Answer 14

Cause suspensions ligament to degenerate & Completes the shortening of the gubernaculum (with help of INSL3) & movement of testes into scrotum

Question 15

What is Sertoli cell functions?

Answer 15

-Essential regulator of testis development; SRY acts to form SC
-forms the blood testis barrier; tight junctions between SC ‘seal off’ the lumen of the tubule, they prevent autoimmune attack of haploid germ cells
-secrete AMH; prevents paramesonephric duct development
-in adult, maintains the leydig cell

Question 16

Peritubular myoid cell
-role
-dependant on what

Answer 16

-Contract tubules, & essential for normal spermatogenesis
-androgen dependant

Question 17

Testis should be what temp less/more than body temp

Answer 17

Around 3C cooler

Question 18

Describe testicular thermoregulation (counter current exchange)

Answer 18

Warm blood coming down via testicular artery is cooled by cool blood that is returning into body by testicular vein; wrap around one another to produce counter current exchange that allows blood to cool

Question 19

Name other aids to thermoregeulation

Answer 19

-Tunica dartos- smooth muscle in scrotum capable of elevating testis to cooler conditions
-cremaster muscle- capable of short term contractions & short term elevation of testes during fear and excitement

Question 20

An animal affected by failure of testis descent is called…

Answer 20

Cryptorchid

Question 21

What is failure of testis descent caused by

Answer 21

Problems with AMH, androgens, CCRP or other factors
May be inherited

Question 22

What is testis function controlled by?

Answer 22

-primarily by
endocrine regulation through LH and FSH
secretion from the anterior pituitary
-some input from ACTH, GH an thyroid hormones

Question 23

Feedback from testosterone from testes is -ve or +ve?

Answer 23

Negative

Question 24

Describe control of testis

Answer 24

1.LH acting on leydig cells releases testosterone
2. Testosterone acts on Peritubular myoid cells that act on Sertoli cells
3. Sertoli cells in turn act on leydig cells
4. FSH also acts on Sertoli cells

Question 25

Summary of factors and hormones involved in testis

Answer 25

On anki

Question 26

What is spermatogenesis

Answer 26

Generation of sperm-Massive amplification of cell numbers of sperm

Question 27

Why must cell differentiation occur?

Answer 27

To generate a motile package

Question 28

Describe process of spermatogensis

Answer 28

1. Proliferation of spermatogonia- 1 cell produces 64 cells
2. Enter period of meiosis during puberty- spermatogonia becomes primary spermatocyte
3. Go through first meiosis to form secondary spermatocyte
4. Secondary spermatocyte undergo second meiosis to form round spermatids- haploid with singl chromatids
5. Spermatids develop into sperm cells by going through differentiation. Differentiate into elongated sperm cell (spermiogenesis)

Diagram on anki

Question 29

How long does spermatogenesis take in:
-dog
-humans
-bull
-ram

Answer 29

56-93 days in dog
64d in human
60d bull
49d ram

Question 30

Once a spermatogonium develops to meiosis then the next spermatogonium starts maturing behind it

Answer 30

Just know this

Question 31

To ensure there is
continuous sperm
production each Sertoli
cell (SC) supports how many germ cells at different stages of cycle

Answer 31

20-30

Question 32

How is spermatogenesis controlled?

Answer 32

Control through Sertoli cells

Question 33

Epididymis
Function
Where does sperm enter
What does tail act as

Answer 33

Tube that Carries sperm and induces sperm maturation

• Non-motile, non-fertile sperm enter at the head and then become fertile and motile as they travel down the epidiymis
• The tail acts as a sperm storage area.

Question 34

What kind of epithelium is found in epididymis?

Answer 34

Pseudostratified, columnar epithelium with stereolcilia Epithelium gets smaller towards the tail

Question 35

Exocrine or endocrine accessory glads are found in testis?

Answer 35

Exocrine glands