10 - The Gonads 1 Flashcards
What do the gonads develop as in males?
The testes
What do the gonads develop as in females?
The ovaries
What genes cause differentiation into testes?
Genes on the Y chromosome.
What are the 2 functions of the gonads?
- Production of gametes for reproduction (gametogenesis)
2. Production of steroid hormones (steroidogenesis)
What gametes are produced in males? What is this process called?
Spermatogenesis.
Production of mature spermatozoa.
What gametes are produced in females? What is this process called?
Oogenesis.
Production of ripe ova.
What steroid hormones are produced in males?
Androgens.
Some oestrogens and progestogens
What steroid hormones are produced in females?
Oestrogen and progestogens.
Some androgens
What happens to the amount of oogonia throughout life?
Max number at 24 weeks old.
Decrease before birth (atresia)
Even lower by puberty.
Finite number so run out at menopause.
What happens to the amount of spermatogonia throughout life?
Peaks before birth.
Remains at same height throughout life.
Dips a bit at old age.
When does spermatogenesis start and what causes this?
Starts at puberty.
Caused by GRH and testosterone.
Outline the process of spermatogenesis.
Germ cell (2n)
Spermatogonia (2n)
(Mitotic division)
Primary spermatocytes (2n) (1st meiotic division)
Secondary spermatocytes (n) (2nd meiotic division)
Spermatids (n)
Spermatozoa (n)
Where does spermatogenesis happen?
Seminiferous tubules
Outline the process of oogenesis.
Germ cell (2n)
Oogonia (2n)
(Mitotic division)
Primary Oocytes (2n) (1st meiotic division)
Secondary oocytes (n)
(+ first polar body)
(2nd meiotic division)
Ovum (n)
(+ second polar body)
When does oogenesis pause in females?
The prophase of meiosis 1 pauses until puberty.
How many oogonia are there in primordial follicles?
6 million.
By birth this reduces to 2 million.
What is atresia?
Degeneration of follicles
Where are the testes found and what conditions are they kept in?
Found in the scrotum.
Kept 2-3 degrees cooler than body temp.
What route do the spermatozoa take to get out of the seminiferous tubules?
Go to the end of the tubule. Collect at rete testis Drain into Vasa efferentia Travel through epididymus via vas deferens (surrounded by smooth muscle) to urethra
Where are sertoli cells found?
Lining the lumen off the seminiferous tubule. (They form the tubule)
Where are Leydig cells found?
Surrounding the outside of the sertoli cells.
Where are the spermatogonia found?
Outside the sertoli cells.
What is the function of the Sertoli cells?
Blood-testes barrier.
Make FSH and androgen receptors.
Produce inhibit in response to FSH.
Nourish the germ cells.
What is the function of leydig cells?
Contain enzymes for steroidogenesis.
Make LH receptors
Make androgens in response to LH.
