Facts of follicular growth in Ovary

 

Follicles in the ovary of a girl child are not growing and are in the sleeping stage. They start growing cyclically once the girl attains menarche.

Follicles in the ovary grow progressively in the early half of menstrual cycle. In the later half they regress if pregnancy does not happen. If the woman falls pregnant the ovulated  follicle starts secreting hormones and maintains the pregnancy.

Each mature follicle contains an egg surrounded by cells called cumulus. Mature eggs have cumulus which are loosely bound where as immature eggs are surrounded by compact cumulus.

In IVF egg is collected by follicular aspiration. The egg which floats in the follicular fluid after HCG trigger is aspirated with its surrounding cumulus.

A mature egg only can be fertilised by a sperm. Mature egg has completed its cell growth and ready to fertilise with sperm. It has loosened it cumulus for easy entry of sperm. A healthy sperm can dissolve the wall of egg (called zona ) and enter inside.

Healthy sperms with good movement are essential to fertilise an egg. Sperms with rapid movement can travel upto the egg in the fallopian tube. They produce enzymes which can dissolve the zona pellucida and allow entry of a sperm.

In ultrasonic monitoring we can only see the follicle filled with fluid. Very small follicles in early days of menstruation can not be seen in ultrasound imaging. As the follicle grow they are filled with fluid and become visible in USG.

Human eggs are not visible to naked eye and can only be seen under microscope. Follicular monitoring can tell us about the number of follicles but not eggs. Some of the follicles may be empty and may not contain an egg at all.