Mention the relationship between concentration of luteinising hormone and maintenance of endometrium in the human uterus.

Mention the relationships between pituitary and ovarian hormones during a menstrual cycle.

Write the location and functions of the following in human testes:

1. Sertoli cells.
2. Leydig cells.

Where does the first cleavage division of zygote take place?

When and where do chorionic villi appear in humans? State their function.

What are the events taking place in the ovary and uterus during follicular phase of the menstrual cycle?

Name the muscular and glandular layers of human uterus. Which one of these layers undergoes cyclic changes during menstrual cycle? Name the hormone essential for the maintenance of this layer.

Mention the number of cells in the following stages:

S. No	Embryonic stages	No. of cells
(i)	Zygote	______________
(ii)	Morula	______________
(iii)	Blastocyst	______________

How does zona pellucida of ovum help in preventing polyspermy?

Name the stage of the human embryo that gets implanted in the uterus and draw its labeled diagram.