Spermatogenesis Process

Sperm Production in Testicles

• Sperm production occurs in the seminiferous tubules of the testicles.

Leydig Cells

• Leydig cells are located in the interstitial tissue of the testicles and produce testosterone in response to luteinizing hormone (LH).

Testicular Structure

• The testis is divided into 250-300 pyramidal compartments or testicular lobules.
• The tunica albuginea is a layer of fibrous tissue surrounding the testis, providing support and protection.

Embryonic Development

• The testes develop embryonically in the abdomen near the kidneys before moving to the scrotal sac.

Sperm Production Process

• The first part of sperm production involves mainly mitosis and meiosis, known as spermatocytogenesis.
• Spermatogonia act as stem cells, dividing infrequently and giving rise to more rapidly dividing cells.

Meiosis

• The first meiotic prophase is characterized by cells with partially condensed chromosomes in various stages of synapsis and recombination, known as zygotene.
• The second meiotic division involves homologous chromosomes separating and producing secondary spermatocytes.
• The result of the second meiotic division is the formation of haploid spermatids.

Spermatogenesis

• Intercellular bridges allow for free cytoplasmic communication among male germ cells during mitotic and meiotic divisions.
• The pampiniform venous plexus surrounding the testicular artery helps regulate testicular temperature.

Hormone Regulation

• Luteinizing hormone (LH) triggers testosterone synthesis in interstitial cells (Leydig cells).
• Fetal interstitial cells produce testosterone during embryonic development.
• Testosterone promotes the development of secondary male sex characteristics.

Spermiogenesis

• During spermiogenesis, the cytoplasm of spermatids is eliminated.
• Type A spermatogonia act as stem cells, dividing infrequently and giving rise to more rapidly dividing cells.
• Intercellular bridges allow for the exchange of molecules and ions between spermatogenic cells.

Sertoli Cells

• Sertoli cells physically and metabolically support developing sperm cell precursors.
• Sertoli cells secrete inhibin, which feeds back on follicle-stimulating hormone (FSH) to regulate spermatogenesis.
• Sertoli cells produce müllerian-inhibiting substance (MIS) in the fetus, which prevents the development of female reproductive structures.
• Sertoli cells secrete transferrin, which helps regulate iron levels in the testes.
• Sertoli cells produce androgen-binding protein (ABP), which helps regulate testosterone levels.
• Sertoli cells form the blood-testis barrier, which separates the testicular tissue from the bloodstream.

Sperm Development

• During spermiogenesis, excess cytoplasm is shed as residual bodies.
• The acrosome phase of sperm development involves the formation of a structure that remains embedded in the Sertoli cell.
• The middle piece of the sperm develops from the aggregation of organelles around the flagellum.
• Protamines are proteins that help compact the sperm nuclei during sperm development.

Blood-Testis Barrier

• The main function of tight occluding junctions in Sertoli cells is to form the blood-testis barrier.
• The three general functions of Sertoli cells in establishing the blood-testis barrier are to regulate the movement of molecules, to provide mechanical support, and to secrete factors that influence spermatogenesis.

Unknown Function

• One of the functions of exocrine secretion by Sertoli cells is to provide nutrients to developing sperm cells.

Test your knowledge on the process of spermatogenesis, from the stem cells to the formation of mature spermatozoa. Learn about the different stages such as mitosis, meiotic divisions, and spermiogenesis.