Does oogonia undergo mitosis or meiosis?

Oogonia proliferate via mitosis during the 9th to 22nd week of embryonic development. There can be up to 600,000 oogonia by the 8th week of development and up to 7,000,000 by the 5th month. Eventually, the oogonia will either degenerate or further differentiate into primary oocytes through asymmetric division.

Is Oogonium the same as primary oocyte?

Oogonia are tiny diploid germ cells that pass through mitotic divisions and originate the primary oocytes. In general, these cells have a large nucleus and a small amount of cytoplasm (Guraya, 1986).

Does Oogonium have two sets of chromosomes?

Once the primordial germ cell arrives in the gonads, it is influenced by the surrounding cells to become oogonium (plural, oogonia). Oogonia are diploid cells. This means they have two (di) complete sets of chromosomes. In the human cell, this is 23 pairs or a total of 46.

Do oogonia undergo meiosis?

From early in gestation, fetal oogonia enter meiosis, reaching the first prophase stage, whereupon they become arrested and remain so for up to 50 years until just before ovulation. During this arrest, the oocyte with the surrounding layer of flattened granulosa cells is known as a primordial follicle.

How is the proliferation of oogonia cells controlled?

Lubzens et al. (2010)reviewed the molecular and hormonal mechanisms that control the proliferation of oogonia. This subject remains unknown in native species, but it is known that, in general, in ovaries still “developing,” the oogonia divide mitotically, producing cell groupings called “oogonia nests.”

How are oogonial stem cells used in mitosis?

In 1967, Loannou et al., studied proliferation of oogonia and sought to identify whether they were undergoing mitosis. They would be able to show this if there was observance of mitotic activity and whether or not they were contributing to stem cell populations. To do this, they used haematoxylin stains to stain for mitotic divisions.

When do oogonia migrate to the fetal cortex?

During the first trimester of pregnancy, primordial germ cells called oogonia migrate to the fetal ovarian cortex and proliferate. By mid-gestation, some oogonia begin the first stage of meiotic division and are subsequently referred to as primary oocytes.

How does meiotic division occur in the oogonia?

Oogoniaproliferate mitotically under the stimulation of E2 (Figure 2). Meiotic division commences in a subpopulation of the oogonia that can be visualized by the presence of synaptonemal complexes (a hallmark feature of homologous chromosomal synapses).