Question

Cleavage are repeated mitotic division which start in zygote at:

• A. Uterus
• B. Fimbria
• C. Infundibulum
• D. Isthmus

Answer 1

The correct option is D Isthmus

Cleavage is the repeated mitotic division of zygote to form a solid ball of cells called morula which later changes into a hollow ball of cells called blastula. Cleavage of the human zygote starts at isthmus of the oviduct and forms 2, 4, 8, 16 daughter cells called blastomeres. The embryo with 8 to 16 blastomeres is called a morula. The morula continues to
divide and transforms into blastocyst as it moves further into the uterus. Finallt, the blastocyst becomes embedded in the endometrium of the uterus.