11.4 Sexual Reproduction

Question 1

What is oogenesis?

Answer 1

Production of egg cells in the ovaries. It starts in the ovaries of a female fetus. Germ cells in the fetal ovary divide by mitosis and the cells formed move to distribute themselves through the cortex of the ovary. These cells start to divide by meiois. By the seventh month they are still in this first division of meiosis (propase 1). No further development takes place until after puberty.

Primary folicle
oogonium
oocyte
secondary oocyte

Question 2

How is polyspermy prevented?

Answer 2

The zona pellucida is a coat of glycoproteins that surround the egg. The acrosome is a large membrane bound sac of enzymes in the head of the sperm. In mammals, the sperm binds to the zona pellucida and the contents of the acrosome are released