Lecture 9: Reproduction - male embryonic and postnatal

Cells that are capable of dividing to produce both more stem cells and specialized germ cells (sperm or oocytes).

Unipotent refers to a stem cell that can only develop into one specific type of cell, in this case, sperm or oocytes.

A cell that has reached its final stage of development and cannot further divide or differentiate.

The fertilized egg cell, which has the potential to develop into any cell type of the organism.

The process by which germline stem cells produce mature sperm or oocytes.

The genetic material carried within sperm and oocytes, which is passed down to offspring.

Genetic defects present within germ cells pose a risk of being inherited by offspring, potentially causing developmental abnormalities or disorders.

The process of removing epigenetic marks from somatic cells, allowing germ cells to revert to a blank slate for reprogramming.

The process of switching on genes that are specific to germ cells, while silencing genes that are specific to somatic cells.

The process of reducing levels of 5-methylcytosine in DNA, which helps remove epigenetic imprints.

Germ cells inherit different epigenetic patterns depending on whether they will develop into sperm or eggs.

A process that begins at puberty in males and continues throughout life, resulting in the continuous production of sperm.

The process of a female germ cell (oocyte) pausing its development in prophase I of meiosis during embryogenesis.

The process of female germ cells (oogonia) entering meiosis during embryogenesis.

The process of female germ cells completing meiosis only upon fertilization.

A process that begins with a group of cells called oogonia, which pause their development and await fertilization.

Primordial germ cells (PGCs) are the precursors of sperm and eggs, initially capable of becoming either one.

PGCs maintain their potential to become many cell types, including sperm or eggs, even as they journey to the gonads.

The journey PGCs undertake to reach the gonads, where they'll become sperm or eggs.

In the testis, PGCs enter a state of rest, waiting to become sperm at puberty.

In the ovary, PGCs enter meiosis but pause in the early stages, resuming and completing the process later.

The Y chromosome carries a gene called SRY, which is responsible for initiating the development of male characteristics.

SOX9, a gene activated by SRY, plays a crucial role in male germ cell development and testis formation.

FGF9 is a growth factor that promotes testis development, influenced by SOX9.

A cascade of genes, starting with SRY, leads to the development of male germ cells and the formation of seminiferous cords, the building blocks of the testis.

These cords, formed in the testis, are essential for spermatogenesis, the process of making sperm.

Spermatogonial stem cells (SSCs) have the ability to divide and create more SSCs, ensuring a continuous supply of germ cells for spermatogenesis.

SSCs can differentiate into sperm-producing cells, demonstrating their key role in spermatogenesis.

The study injected LacZ+ tagged SSCs into testes lacking germ cells, demonstrating that SSCs can repopulate the testes and restore spermatogenesis.

The presence of β-galactosidase activity in the testes of recipient mice confirmed that the injected LacZ+ SSCs successfully repopulated the testes.

The repopulated testes produced sperm, indicating the functional ability of the injected LacZ+ SSCs to contribute to normal spermatogenesis.

The process of mature sperm being released into the seminiferous tubules and then transported to the epididymis for further maturation.

The stage at which sperm acquire full motility and the ability to fertilize an egg.

Spermatogonial stem cells are primarily undergoing self-renewal to establish the future stem cell pool.

Spermatogonia are present and proliferate, but meiosis and spermatogenesis are not actively occurring.

Spermatogonial stem cells begin the process of differentiation, with one daughter cell maintaining the stem cell population and the other progressing through meiosis and spermiogenesis.

Spermatogenesis is a continuous process, with millions of sperm being produced daily.

The process of a female germ cell (oocyte) pausing its development in prophase I of meiosis during embryogenesis.

The process of female germ cells (oogonia) entering meiosis during embryogenesis.

The process of female germ cells completing meiosis only upon fertilization.

A process that begins with a group of cells called oogonia, which pause their development and await fertilization.