BBS1005 summary of case 1 should we worry

Case 1: Should we worry?

, 1. What is Gametogenesis?
Gametogenesis: is the process that converts primordial germ cells to mature
male(spermatozoa) and female gametes(oocytes). Gametogenesis consists of 4 phases:
1. The migration of germ cells (identical in males and females)
2. The increase of primordial germ cells via mitosis
3. The reduction of chromosomes number via meiosis
4. The maturation of the eggs and spermatozoa


1. Migration of germ cells:
Primordial germ cells (PGC) are the precursors of the gametes, they exit from the
yolk sac into the hindgut and migrate to the primordia of the gonads.
2. Increase of primordial germ cells via mitosis:
When PGC reach the gonads they start a phase of rapid mitotic proliferation.
Oogonia go through a period of intense mitotic activity in the ovary from the 2nd
to the 5th month of pregnancy. (from few thousand to 7 million)
For spermatogonia mitosis starts early in the embryonic testes. Male germ cells
maintain the ability to divide throughout postnatal life.

Mitosis: is the process whereby one cell gives rise to 2 identical cells, each with a complete
complement of 46 chromosomes.