Gametogenesis Review Materials

1. LECTURES ON
REPRODUCTIVE SYSTEM
Prasanta Deb
Assistant Professor
Department of Human Physiology
M.B.B. College, Agartala

2. GAMETOGENESIS Lecture 1 & 2
a. Oogenesis
stages of meiosis in the female ovarian maturation, hormones
and cycles ovulation
b. Spermatogenesis Lecture 3
stages of meiosis in the male differentiation (spermiogenesis)
FERTILIZATION Lecture 4
a. Where it takes place
b. How it takes place
OUTLINE

3. SOME TERMS
Gamete: egg or sperm
Gametogenesis: production of eggs or sperm
Oogenesis: production of eggs
Spermatogenesis: production of sperm
Spermiogenesis: differentiation of sperm morphology
Follicle: where eggs mature in the ovary
Ovulation: release of egg from follicle
Polar body: nonfunctional product of meiotic divisions in
oogenesis
Zygote: Fertilized egg

4. SOME MORE TERMS
Oogonia: mitotically dividing cells in the ovary, will become
Oocytes
Primary oocyte: decision has been made to undergo meiosis,
cell has grown. Cells are arrested at this stage until puberty.
Secondary oocyte: has completed first meiotic division the
division was unequal in terms of cytoplasm
Ovum: Ovulated egg, ready to be fertilized. If fertilized, the
second meitoic division will occur, another polar body will be
given off.

8. Histology of testis

9. HISTOLOGY OF TESTES
Tunica Vasculosa

12. HISTOLOGY OF TESTES

14. Spermatogenesis

15. Spermatogenic cycle
A1
2A1
Mitosis
3A2
A1
Mitosis
6B1
Mitosis
12B2
Mitosis
24 primary spermatocytes
Mitosis
48 secondary spermatocytes
Meiosis I
96 spermatids
Meiosis II
96 mature spermatozoa
Spermiogenesis
= Spermateleosis
= Spermatozoan metamorphosis
First meiotic division lasts
several weeks in humans
Second meiotic division takes about
8 hours in humans
The following is an example of how the number of spermatozoa is increased by repetitive mitotic
divisions of spermatogonial cells followed by the two meiotic divisions. There are actually more than 4
types of spermatogonia, so the actual number of mature spermatozoa originating from the initial
division of a type A1 spermatogonium is actually greater than 96.
Reductional division
Equational division
An entire spermatogenic cycle in
humans takes about 64 days.
The maturing spermatids remain attached by cytoplasmic bridges as they mature => syncytium

19. THANK YOU