PHYSIOLOGY - Testicular Physiology

Question 1

What are the three main somatic cell types found in the adult testis?

Answer 1

Leydig cells
Sertoli cells
Peritubular myoid cells

Question 2

Where are the Leydig cells located within the testis?

Answer 2

Leydig cells are located in the interstitial space between the seminiferous tubules

Question 3

What are the two different types of Leydig cells found within the mammalian testis?

Answer 3

Foetal/neonatal Leydig cells
Adult Leydig cells

Question 4

What is the function of Leydig cells?

Answer 4

Leydig cells synthesise androgens and insulin-like growth factor (INSL3)

Question 5

What are the two peaks of Leydig cell androgen production?

Answer 5

Foetal peak
Pubertal peak

Question 6

What is the purpose of the foetal peak of Leydig androgen production?

Answer 6

The foetal peak ensures masculanisation of the external genitalia

Question 7

What is the purpose of the pubertal peak of Leydig androgen production?

Answer 7

The pubertal peak is essential for fertility, libido and the maintenance of secondary sexual characteristics

Question 8

What regulates Leydig cell function?

Answer 8

Leydig cell function is regulated by the LH pulses from the anterior pituitary gland

Question 9

Where are the Sertoli cells located within the testis?

Answer 9

The Sertoli cells are located at the basement membrane of the seminiferous tubules

Question 10

What are the three functions of the Sertoli cells?

Answer 10

Regulation of spermatogenesis
Form the blood testis barrier
Secrete AMH (anti-mullerian hormone)

Question 11

What is the function of the blood testis barrier?

Answer 11

The blood testis barrier protects the developing sperm from autoimmunity as the immune system recognises the haploid sperm as foreign. The blood testis barrier seals off the lumen of the seminiferous tubules from the blood stream

Question 12

What regulates Sertoli cell function?

Answer 12

Sertoli cell function is regulated by FSH secretion from the anterior pituitary gland as well as androgen secretion from the Leydig cells

Question 13

Where are the peritubular myoid cells found within the testis?

Answer 13

The peritubular myoid cells surround the seminiferous tubules

Question 14

Which hormones are essential for testicular descent into the scrotum?

Answer 14

Androgens (testosterone)
Insulin-like growth factor (INSL3)

Question 15

How does testosterone and insulin-like growth factor (INSL3) regulate testicular descent?

Answer 15

Testosterone begins the shortening of the gubernaculum and INSL3 completes the shortening and the movement of the testes into the scrotum

Question 16

What is spermatogenesis?

Answer 16

Spermatogenesis is the proliferation and development of spermatogonia into spermatids

Question 17

What is spermiogenesis?

Answer 17

Spermiogenesis is the differentiation of the spermatids into sperm

Question 18

What occurs during the proliferation stage of spermatogenesis?

Answer 18

The spermatogonia undergo mitosis and thus proliferation

Question 19

At what age do spermatogonia undergo meisosis?

Answer 19

Puberty

Question 20

What occurs during the meiosis stage of spermatogenesis?

Answer 20

1. Spermatogonia enter meiosis and develop into primary spermatocytes
2. Primary spermatocytes undergo meiosis I and develop into secondary spermatocytes
3. Secondary spermatocytes undergo meiosis II and develop into spermatids

Question 21

What occurs during spermiogenesis?

Answer 21

Spermatids differentiate from circular cells to sperm cells with a head and a tail

Question 22

How do the Sertoli cells ensure there is continuous sperm production?

Answer 22

Each Sertoli cell will support 20-30 spermatogonia throughout each stage of sperm production

Question 23

Where are spermatogonia found within the seminiferous tubules?

Answer 23

Spermatogonia are found at the basement membrane within the Sertoli cells

Question 24

Where are sperm found within the seminiferous tubules?

Answer 24

Sperm are found within the lumen of the seminiferous tubules

Question 25

Where do the non-motile and non-fertile sperm travel to undergo maturation?

Answer 25

The sperm travel to the head of the epididymus and will mature as they move through to the tail of the epididymus

Question 26

What type of epithelium does the epididymus have?

Answer 26

Pseudostratified columnar epithelium with stereocilia

Question 27

How long does the process of spermatogenesis (from spermatogonia to mature spermatozoa) take in the ram?

Answer 27

49 days