Question 1

How many functional ova are produced from one primary oocyte?

Accepted Answer

Only one. Unequal cytokinesis channels nearly all cytoplasm into a single ovum; the two polar bodies produced during meiosis I and meiosis II are tiny, non-functional structures that degenerate.

Question 2

When does oogenesis begin in humans?

Accepted Answer

During foetal life. Oogonia multiply and enter meiosis I to become primary oocytes before birth, and no new oogonia are formed after birth. Primary oocytes then remain arrested in prophase I until puberty.

Question 3

What is a polar body?

Accepted Answer

A polar body is the tiny cell produced during the unequal divisions of oogenesis. It receives almost no cytoplasm, carries a haploid nucleus, and degenerates. Its formation is what allows one primary oocyte to yield a single nutrient-rich ovum.

Question 4

When does the secondary oocyte complete meiosis II?

Accepted Answer

Only if fertilisation occurs. The secondary oocyte is ovulated while arrested at metaphase II; entry of a sperm triggers completion of meiosis II, producing the ovum and the second polar body.

Question 5

What is the difference between Sertoli cells and Leydig cells?

Accepted Answer

Sertoli cells are nurse cells inside the seminiferous tubules that nourish developing sperm and are stimulated by FSH. Leydig (interstitial) cells lie outside the tubules and secrete testosterone (androgens) under the influence of LH.

Spermatogenesis vs Oogenesis: Four Versus One

Practice

Learned it? Now prove it under the clock.