Anatomy Unit 201: Cell Cycle and Gametogenesis

Questions and Answers

During fetal life (correct)

With each ovarian cycle

At birth

At puberty

Following fertilization

Mitosis is somatic cell division for growth and repair, while meiosis is a reduction division that produces gametes.

Spermatocytogenesis and spermiogenesis.

In the outer cortex of the ovary. Signup and view all the answers

All of the above Signup and view all the answers

The absence of sperm in semen. Signup and view all the answers

False Signup and view all the answers

2 million. Signup and view all the answers

True Signup and view all the answers

Study Notes

The cell cycle consists of interphase (growth and DNA replication) and the mitotic phase (cell division).
Mitosis is somatic cell division, occurring in somatic tissues for growth and repair.
Meiosis is gametic cell division, taking place in gonads (testes and ovaries) to produce gametes.

Mitosis results in two identical daughter cells, maintaining the diploid chromosome number.
Meiosis consists of two divisions: meiosis I (reduction division) and meiosis II, resulting in four haploid gametes.
Meiosis I includes DNA replication and crossing over; no DNA replication occurs in meiosis II.

Reduces diploid chromosome number (2n) to haploid (n) for reproductive purposes.
Facilitates genetic diversity through shuffling of chromosomes and crossing over.

Transformation of spermatogonia into spermatozoa, occurring in seminiferous tubules of the testes.
Duration of spermatogenesis is approximately 64 days, starting at puberty and continuing throughout life.
Comprises spermatocytogenesis (division of spermatogonia into spermatids) and spermiogenesis (maturation of spermatids).

Volume: 3-5 cc; has a characteristic odor and alkaline reaction.
Contains about 200-600 million sperm per ejaculation; motility exceeding 80%.
Provides nutrients (fructose) for sperm, prostaglandins for motility, and balances vaginal acidity.

Azospermia: absence of sperm in semen.
Oligospermia: low sperm count.
Necrospermia: presence of dead sperm.
Morphological abnormalities: giant or dwarf sperm, abnormal head/tail counts; should not exceed 20%, normally under 10%.

Oogenesis is the process of forming mature ova from oogonia in the ovarian cortex.
Primary oocytes begin meiosis I during fetal life but remain dormant until puberty.
Monthly during the menstrual cycle, 5-12 primary oocytes complete meiosis I, forming a secondary oocyte and a polar body.
Secondary oocyte completes meiosis II only upon fertilization, arrested in metaphase prior to this.

Total primary oocytes in newborn females: approximately 2 million, decreasing to about 40,000 during adolescence.
Only around 480 primary oocytes are ovulated throughout a woman’s reproductive life.

Male gametogenesis (spermatogenesis) produces multiple sperm continuously, while female gametogenesis (oogenesis) produces limited ova with cyclic release.
Male gametes are smaller and more numerous; female gametes are larger and fewer.