Fertilizin is a chemical substance produced from

What is the most likely reason for the absence of regular menstruation in women?

During human fertilization, which of the following induces changes and acts as a barrier to ensure that only one sperm can enter and fertilize the ovum?

Amphimixis means

In the blastocyst,the blastomeres are arranged into an outer layer called _ $A$ _ and an inner group of cells attached to the trophoblast,called _ $B$ _.

Which of the following is $NOT$ a characteristic of cleavage?