Lecture 16 Spermatogenesis 2

Spermatogenesis

The process of sperm cell development in male animals.

Undifferentiated Spermatogonia

Immature male germ cells that are localized to a single spot in the gonad and proliferate.

Primordial Germ Cells (PGCs)

The initial cells that will develop into sperm or eggs, colonizing the embryonic gonad.

Meiotic Spermatocytes

Cells that undergo meiosis during spermatogenesis, leading to the formation of haploid sperm cells.

Spermiogenesis

The final stage of spermatogenesis where spermatids mature into spermatozoa.

Morphogen

An agent that causes morphogenesis, influencing the development of morphological traits.

Retinoic Acid (RA)

A biologically active metabolite of Vitamin A that plays a crucial role in spermatogonial differentiation.

Mammalian Spermatogenesis

A process that generates a constant supply of sperm from juvenile to geriatric stages.

Seasonal Breeders

Animals whose reproductive cycles are influenced by seasonal changes in light and day length.

Melatonin

A hormone produced in response to darkness, which regulates reproductive cycles by affecting GnRH secretion.

What are the three male reproductive strategies discussed in comparative spermatogenesis?

1. One Spot, One Shot (C. elegans) 2. All Together (Salmon) 3. Continual (Mammals)

What is the role of undifferentiated spermatogonia in reproductive strategies?

They are localized to a single spot in the gonad and proliferate.

What happens during meiosis in spermatogenesis?

Meiosis and post-meiotic differentiation occur further along the tubule.

What is the typical duration for spermatogenesis in mice?

Approximately 42 days.

What does the term 'morphogen' refer to?

An agent causing morphogenesis, which is the development of morphological traits.

How does mammalian spermatogenesis ensure a constant supply of sperm?

Through periodic differentiation of undifferentiated spermatogonia and consistent rates of cell maturation.

In seasonal breeders, what changes trigger spermatogenesis?

Changes in day length, which affect melatonin production and alter GnRH secretion.

What is the key distinction between long-day and short-day seasonal breeders?

Long-day breeders (e.g., mares) increase spermatogenesis with longer days, while short-day breeders (e.g., sheep) increase it with shorter days.

What is retinoic acid (RA) important for in spermatogenesis?

It is a morphogen that regulates periodic differentiation of spermatogonia.

What are primordial germ cells (PGCs) in relation to spermatogenesis?

PGCs are the initial cells that colonize the embryonic gonad and give rise to spermatogonia.