Understanding Female Reproductive Cycle: From Egg Creation to Ovum Transformation

TLDR; The video explains the female reproductive cycle, the process of egg creation, meiosis, ovulation, and fertilization, and the transformation from a secondary oocyte to an ovum.

⏰ Female Reproductive Cycle

The female reproductive cycle involves the maturation of eggs within the ovaries, which are initially created during gestation and remain in an inactive state until puberty.

At puberty, one egg from the supply in the ovaries matures each month, allowing it to be fertilized by sperm.

The ovaries also secrete female sex hormones like estrogen, progesterone, and inhibin.

🥚 Egg Formation

During early uteral development, precursor germ cells called oogonia undergo mitotic divisions to produce about two to four million eggs, which is the total supply for a female's life.

These oogonia then develop into primary oocytes, each containing two copies of each chromosome and entering meiosis 1 but getting stuck halfway through the process.

🔬 Meiotic Arrest

Primary oocytes are in meiotic arrest when a female is born. Some primary oocytes get past meiotic arrest, while most die off while stuck in this phase.

It's only at puberty that they start moving forward with development.

👩‍🔬 Meiosis Completion

At puberty, the primary oocytes start moving forward with development by finishing off the first part of meiosis, resulting in the formation of two secondary oocytes.

However, one primary oocyte attempts to split into two secondary oocytes, leading to an interesting outcome.

👶 Fertilization Process

Ovulation releases the secondary oocyte, which, if fertilized by a sperm, undergoes the second half of meiosis to reduce its chromosome copy number and create another polar body.

The secondary oocyte then changes its name to an ovum after fertilization.