Lecture 17: Reproduction (sex + differentiation)

Question 1

What is sex? What is needed from both individuals?

Answer 1

-Need for 2 individuals: produce germ cells which fuse to produce an offspring
-Difference (sexual dimorphism) carried by genes= sex chromosomes (mammals XX= F and XY= male)
-During early fetal life, gonads are undifferentiated

Question 2

What is embryonic sex differentiation?

Answer 2

Formation of primordial germ cells (P.G.C’s)
-Extra-embryonic origin
-Circulate in vasculature, migrate through tissues

Colonize the genital ridge to form indifferent gonads

Differentiation of cortex into ovary or medulla into testis - testis organization through transient expression of genes (testes differentiation factor-TDF) from the SRY (Sex-determining region Y)