1.3 Flashcards
2 types
Spermatogenesis
Oogenesis
Gametogenesis is the formation of:
Gametes
Gametogenesis can be divided into 3 stages:
1) multiplication
2) growth
3) maturation
1)multiplication involves the cells:
Dividing by MITOSIS
2) growth phase includes cells produced by mitosis to:
Grow in size
3) maturation includes these cells to divide by:
MEIOSIS to form HAPLOID cells
These then differentiate into gametes
Differences between spermatogenesis and oogenesis:
(O)
- First meiotic division occurs before birth
- Meiosis doesn’t finish until after fertilisation
- Haploid cells divide unequally (tin polar bodies formed)
- Only one ovum formed
(S)
- All the haploid cells formed from meiosis develop into sperm
- Occurs after puberty
- Occurs all the time
- Every primary spermatocyte produces 4 sperm cells
Testes contain seminiferous tubules which is where
Sperm are produced
The outer layer of the seminiferous tubules is made up of GERMINAL EPITHELIUM, this is where the cells
Divide by MITOSIS during the MULTIPLICATION STAGE
(SotT)As the cells divide they move towards the centre of the tubules - these cells are called
Spermatogonia
(SotT)As the spermatogonia move nearer to the centre, the growth stage occurs and the spermatogonia develop into:
Primary spermatocytes
Finally meiosis occurs
(SotT) after the first meiotic division they are called
Secondary spermatocytes
(SotT) the haploid cells formed at the end of meiosis are called
Spermatids
Spermatids ember themselves into large Sertoli cells which:
supply the developing sperm with nutrients
Protect the sperm from the immune system as they are genetically different from the body cells
(SotT) the sperm released into the lumen of the seminiferous tubules are still not fully mature and cannot swim. They pass to the epididymis where they become
Fully motile but they still need to undergo further changes before they are capable of fertilising an egg
