The cavity of gastrula is called

Ostium is provided with a number of finger like processes fimbriae

By the contraction of spermatic cord the testis of man are not taken to the abdominal cavity. It is due to the following structure

Which of the embryo has parasite mode of nutrition.

Give the name of two hormones $A$ and $B$ in the figure given below

Sperm enters from which part of egg?