Which two events in the life cycle maintain the same (constant) number of chromosomes?

Which of the following statements are true about the female reproductive system?
$(A)$ Both estrogen and progesterone are necessary for development of follicle
$(B)$ Progesterone production is under the control of $LH$
$(C)$ The part of the oviduct is isthmus; has a narrow lumen and it joins the uterus
$(D)$ During pregnancy all events of the menstrual cycle stop and there is no menstruation
$(E)$ The graafian follicle ruptures to release the primary oocyte from the ovary by the process called ovulation

What is the oestrous cycle?

Release of spermatozoa from the urethra by male animals is called:

In the egg of a bird,the shell and shell membranes are:

Give differences between:
$(a)$ Testis and ovary
$(b)$ Sperm cell and ovum (egg) cell