Cleavage is a unique form of mitotic cell division in which

Which of the following changes occur in the fetus after $24$ weeks of gestation?

Find the correct statements :
$A.$ In human pregnancy,the major organ systems are formed at the end of $12$ weeks.
$B.$ In human pregnancy the major organ systems are formed at the end of $8$ weeks.
$C.$ In human pregnancy heart is formed after one month of gestation.
$D.$ In human pregnancy,limbs and digits develop by the end of second month.
$E.$ In human pregnancy the appearance of hair is usually observed in the fifth month.
Choose the correct answer from the options given below.

The first sign of a growing fetus can be noticed by:

During gastrulation,a cavity is formed and is found in the mature gastrula. What is it called?

Which of the following is not correct for gastrulation?