Question

1. How are identical twins formed in human development?

2. How does the syncytiotrophoblast contribute to implantation of the human embryo?

Answer 1

Ansa Sperm fenklized tog divideo embryos THE FORMATION OF IDENTICAL TWINS INVOLVED ONE eng AND ONE SPERM • AFTER PERTILIZATION OF ONE egg AND ONE SPERM, ZYGOTE IS FORMED. GLEZYGOTE D IVE DES INTO Two yo . THIS SINGLE ZYGOTE DIVIDES INTO EMBRYOS. • BECAUSE THESE TWINS COME FROM ONE ZYGOTE, they are also known as monozygotic twins.

or The trophoblant differentiates into fuo different cell moonses, shortly before it comes into contact with the endometrium. • The outer :- Syn cyfio tro phoblant (ST) The inner :- Cytotrophoblast (CT) - In the periphery of the ST forums a synkytium dil. , a multi-nucleic layer without cell bounda- ries that arises from the fusion of cytotrophoblast cells. The si produces lytic enzymes and necretes factors that caune apoptosis of the endometrial epithelial cells. The st aho ovossed the basal lamina and penetrates into the stoma that lies below, evoding the wall of capillaries. With the implantation of the blastocysts in the endo- -metrium the ST develops quickly and will entirely Alte surround the embryo as soon as it has completely embedded ütnell in the endometrium