What is oogenesis? With the help of suitable diagram, describe the steps involved in this process. (1+3+1=5)

**OR**

Define menstrual cycle. Describe the various phases of menstrual cycle. (1+4=5)

Question

What is oogenesis? With the help of suitable diagram, describe the steps involved in this process. (1+3+1=5)

**OR**

Define menstrual cycle. Describe the various phases of menstrual cycle. (1+4=5)

Accepted Answer

![Figure — The answered primary asks for the steps of oogenesis with a suitable diagram; the canonical schematic comparin](/figures/human-reproduction/schematic-representation-spermatogenesis-oogenesis-fig-2-8.svg)

>

> [!TLDR]
> Oogenesis is the process of producing a mature ovum from an oogonium through a series of unequal meiotic divisions that begin before birth but are only completed, one at a time, in the cycles following puberty.
>
> **Definition:** Oogenesis is the process of formation of a mature, haploid female gamete (ovum) from a diploid oogonium, occurring within the ovary.
>
> **Steps of oogenesis**
>
> 1. Diploid **oogonia**, formed by mitotic multiplication of primordial germ cells during fetal development, undergo growth to become **primary oocytes**.
> 2. Each primary oocyte begins meiosis-I but becomes **arrested in prophase-I**, remaining in this dormant state (enclosed within a primary follicle) from before birth until puberty.
> 3. Starting at puberty, in each menstrual cycle, one (or occasionally more) primary oocyte resumes and completes **meiosis-I**, dividing unequally to produce a large **secondary oocyte** and a small, non-functional **first polar body** (most of the cytoplasm is retained by the secondary oocyte).
> 4. The secondary oocyte immediately enters **meiosis-II** but again arrests, this time at **metaphase-II**; it is released from the ovary at **ovulation**, still at this arrested stage.
> 5. Meiosis-II is completed only **if fertilisation occurs** — fusion with a sperm triggers completion of meiosis-II, producing the mature **ovum** and a small **second polar body**.
>
> (A simple diagram would show a branching sequence: oogonium (2n) $	o$ primary oocyte (2n, arrested in prophase-I) $	o$ [meiosis-I] $	o$ secondary oocyte (n) + first polar body (n) $	o$ [meiosis-II, only on fertilisation] $	o$ ovum (n) + second polar body (n).)
> …

Q.What is oogenesis? With the help of suitable diagram, describe the steps involved in this process. (1+3+1=5) OR Define menstrual cycle. Describe the various phases of menstrual cycle. (1+4=5)

Concept understanding — Oogenesis Definition

Oogenesis: The Making of an Egg Cell

The Everyday Intuition

The Precise Meaning

Why It Matters

Key Stages in Simple Terms

Q.What is oogenesis? With the help of suitable diagram, describe the steps involved in this process. (1+3+1=5) OR Define menstrual cycle. Describe the various phases of menstrual cycle. (1+4=5)

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