FIRST WEEK OF DEVELOPMENT

CLEAVAGE The two cells formed as described above undergo a series of divisions. One cell divides first so that we have a 3 cell stage of embryo followed by 4 cell stage , a 5 cell stage etc. This process is called cleavage.

Subdivisions of cleavage

• Stage of compaction : at 8 celled stage
• Morula
• Blastocyst : between 4th and 5th day

GERMINAL PERIOD