Reproductive system

 

Meiosis

 

Quick Summary Memory Aid:

• Prophase I arrest = Before birth
• Finish meiosis I = Just before ovulation
• Metaphase II arrest = At ovulation
• Finish meiosis II = Only if fertilized

corpus albicans

if fertilization does not occur the corpus luteum becomes a 

(a) Mature (Graafian) follicle 

(b) secondary oocyte

(c) corpus albicans

(d) Primordial follicle 

The corpus albicans is the final stage of the corpus luteum if pregnancy does not occur.

Here’s a simple breakdown:

1. After ovulation – The follicle turns into the corpus luteum, which secretes progesterone and estrogen.

2. If no pregnancy – The uterus releases prostaglandin F2α, which causes the corpus luteum to degenerate.

3. Corpus albicans – The dead corpus luteum is replaced by fibrous scar tissue called the corpus albicans (literally means “white body”).

4. Outcome – It has no hormonal activity. Over time, it shrinks and disappears from the ovary.

👉 If pregnancy does occur, hCG from the embryo keeps the corpus luteum alive, so it does not become a corpus albicans until later.

Mitosis

Mitosis involves a single cell division and result in two diploid cells 

Meiosis

• Divisions: 2 (Meiosis I and Meiosis II)

• Result: 4 daughter cells

• Chromosome number: Haploid (2n → n, half the parent’s number)

• Genetic variation: Yes, because of crossing over (in Prophase I) and independent assortment.

• Purpose: Produce gametes (sperm and eggs) for sexual reproduction

• completion of meiosis produced four diploid daughter cell 

DNA replication occurs in both meiosis and mitosis

 DNA replications occur prior to both meiosis and mitosis 

meiosis

 DNA replications occur prior to meiosis