Week 1 Objective 1 and 2: list and describe the four phases of gametogenesis

Question 1

Phases of Gametogenesis (4)

Answer 1

1. Extraembryonic origin of germ cells and their migration to the gonads
2. Proliferation of germ cells via mitosis
3. Reduction of chromosomal number 2n –> n
4. Structural and functional maturation of the eggs and spermatozoa

Question 2

1st phase of gametogenesis

Answer 2

Extraembryonic Origin of Germ Cells

Question 3

First appearance of germ cells in human embryogenesis

Answer 3

1. 24 days after fertilization

2. founded in endodermal layer of yolk sac

Question 4

Migration route of germ cells

Answer 4

yolk sac –> hindgut epithelium –> dorsal mesentery —> developing gonads

through dorsal mesentery into developing gonads

Question 5

Male gametes =

Answer 5

spermatozoa

Question 6

Female gametes =

Answer 6

Eggs

Question 7

Teratomas

Answer 7

Growths from misdirected and migrating primordial germ cells

Contain mixtures of highly differentiated tissues