Human Development: Stages and Events!

Stages in Development
1. Fetus has a beating heart.
2. Embryo differentiates into three layers (gastrulation).
3. Blastocyst implants in endometrium
4. Cleavage (mitosis) leads to a large number of cells.

Match each of the developmental stages numbered above with the time period in which it occurs in normal development, as given below
1st week:
2nd week:
3rd week:
4th week+:



Some Events in the Human Reproductive Cycle
1. Pro-embryo release hCG, which maintains hormone levels.
2. A hormone signals the follicle to rupture.
3. Blastocyst is implanted.
4. The egg is fertilized to form a zygote

The above events in the sequence in which they occur during the reproductive cycle are
____, ____, ____, ____