Ovum - Preserved Cell

The egg is a “preserved” cell

The egg is a unique cell in the female body. It is formed during the process of oogenesis even before the birth of a girl and remains “preserved” in the ovary for many years until puberty occurs.

The egg is a very large cell with a diameter of about 0.1 mm. Its cytoplasm is filled with nutrients and is called egg yolk. In the cytoplasm there are special cortical grains and a nucleus with rudimentary spots (nucleoli). The egg is surrounded by protective membranes of the follicle.

The formation of eggs (ovogenesis) occurs in the ovaries. First, primordial cells divide mitotically and form oogonia with a normal diploid number of chromosomes (46). The oogonia then develop into primary oocytes, which surround themselves with a layer of follicular cells, forming ovarian follicles. The division of oocytes stops, and they can remain in this “preserved” state for years.

Only after the onset of puberty do oocytes resume division, but according to a special meiotic type. As a result, an egg is formed containing a haploid set of chromosomes. After the follicle ruptures, the egg is released from the ovary - ovulation occurs.

Thus, the egg is a unique “preserved” female cell, containing only half the genetic material and awaiting fertilization to continue development.