Stages in Development
1. Cleavage (mitosis) leads to a large number of cells without growth.
2. Blastocyst implants in endometrium
3. Embryo differentiates into three layers (gastrulation)
4. Fetus has a beating heart.
Match each of the developmental stages numbered above with the time period in which it occurs, as given
below.
Stage: ________________ _______________ ________________ _______________
Time Period: First week Second week Third week Fourth week and on
Stage: 2 1 3 4
Time Period: Second week First week Third week Fourth week and on