Developmental Biology: Gametogenesis Overview

Study Notes

Gametogenesis

Gametogenesis involves the conversion of primordial germ cells (PGCs) into male and female gametes.
PGCs form in the epiblast during the second week of embryonic development and migrate to the yolk sac wall.
By the fourth week, PGCs move toward developing gonads, reaching them by the end of the fifth week.

Epiblast

The epiblast is responsible for giving rise to all three germ layers and the primordial germ cells.

Clinical Correlates: Teratomas

Teratomas are tumors containing diverse tissues, including bone, muscle, hair, and gut epithelium.
They may originate from pluripotent stem cells or from PGCs that deviate from their migratory pathways during gastrulation.

Chromosome Theory of Inheritance

Traits are determined by specific genes located on chromosomes inherited from both parents.
Humans possess approximately 23,000 genes distributed across 46 chromosomes.
Genes located on the same chromosome tend to be linked and inherited together.
There are 22 pairs of autosomes and one pair of sex chromosomes in humans.

Sex Determination

Primary sex determination is influenced by the SRY gene, located on the Y chromosome.
The SRY gene encodes the testis-determining factor (TDF), which directs the differentiation of the bipotential gonad into a testis.

Bipotential to Specific Gonads

The Wolffian duct develops into male genital structures, aided by Müllerian inhibiting hormone, which causes atrophy of the Müllerian ducts.
The Müllerian duct is responsible for forming female reproductive organs.

Mitosis

Mitosis is the process by which a single somatic cell divides into two identical daughter cells, each containing 46 chromosomes.
DNA replication occurs prior to mitosis during the S phase.

Meiosis

Meiosis is a specialized cell division that occurs in germ cells, reducing chromosome numbers by half to produce haploid gametes.
The process consists of two divisions and includes stages such as DNA replication, synapsis, crossing-over, and the formation of chiasma.
At the conclusion of meiosis I, each daughter cell possesses 23 unique chromosomes, indicating a haploid state.

Description

Explore the process of gametogenesis, where germ cells transform into male and female gametes. This quiz covers the development and migration of primordial germ cells during embryonic development, particularly focusing on their journey from the epiblast to the gonads. Test your knowledge on the key stages and concepts of this critical biological process.