PHYSIOLOGY - Testicular Physiology Flashcards
What are the three main somatic cell types found in the adult testis?
Leydig cells
Sertoli cells
Peritubular myoid cells
Where are the Leydig cells located within the testis?
Leydig cells are located in the interstitial space between the seminiferous tubules
What are the two different types of Leydig cells found within the mammalian testis?
Foetal/neonatal Leydig cells
Adult Leydig cells
What is the function of Leydig cells?
Leydig cells synthesise androgens and insulin-like growth factor (INSL3)
What are the two peaks of Leydig cell androgen production?
Foetal peak
Pubertal peak
What is the purpose of the foetal peak of Leydig androgen production?
The foetal peak ensures masculanisation of the external genitalia
What is the purpose of the pubertal peak of Leydig androgen production?
The pubertal peak is essential for fertility, libido and the maintenance of secondary sexual characteristics
What regulates Leydig cell function?
Leydig cell function is regulated by the LH pulses from the anterior pituitary gland
Where are the Sertoli cells located within the testis?
The Sertoli cells are located at the basement membrane of the seminiferous tubules
What are the three functions of the Sertoli cells?
Regulation of spermatogenesis
Form the blood testis barrier
Secrete AMH (anti-mullerian hormone)
What is the function of the blood testis barrier?
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
What regulates Sertoli cell function?
Sertoli cell function is regulated by FSH secretion from the anterior pituitary gland as well as androgen secretion from the Leydig cells
Where are the peritubular myoid cells found within the testis?
The peritubular myoid cells surround the seminiferous tubules
Which hormones are essential for testicular descent into the scrotum?
Androgens (testosterone)
Insulin-like growth factor (INSL3)
How does testosterone and insulin-like growth factor (INSL3) regulate testicular descent?
Testosterone begins the shortening of the gubernaculum and INSL3 completes the shortening and the movement of the testes into the scrotum
What is spermatogenesis?
Spermatogenesis is the proliferation and development of spermatogonia into spermatids
What is spermiogenesis?
Spermiogenesis is the differentiation of the spermatids into sperm
What occurs during the proliferation stage of spermatogenesis?
The spermatogonia undergo mitosis and thus proliferation
At what age do spermatogonia undergo meisosis?
Puberty
What occurs during the meiosis stage of spermatogenesis?
- Spermatogonia enter meiosis and develop into primary spermatocytes
- Primary spermatocytes undergo meiosis I and develop into secondary spermatocytes
- Secondary spermatocytes undergo meiosis II and develop into spermatids
What occurs during spermiogenesis?
Spermatids differentiate from circular cells to sperm cells with a head and a tail
How do the Sertoli cells ensure there is continuous sperm production?
Each Sertoli cell will support 20-30 spermatogonia throughout each stage of sperm production
Where are spermatogonia found within the seminiferous tubules?
Spermatogonia are found at the basement membrane within the Sertoli cells
Where are sperm found within the seminiferous tubules?
Sperm are found within the lumen of the seminiferous tubules
