Seminiferous Tubules

Sperm Factories

Seminiferous tubules are the reproductive organs that generate spermatozoa.

Spermatogonia

Spermatogonia are positioned along the superficialNear the surface of the body. area of the tubule, up against myoid cellsThe basic structural and functional units of life. that are smooth muscle cells. Spermatogonia are capable of doing mitosis, replacing themselves with a new cell and generating a new cell to develop into four spermatozoa via meiosis.

Spermatocytes

As that one cell does meiosis, the cell transforms through life stages such as a primary spermatocyte, and secondary spermatocyte, and spermatids (which are not yet fully functional spermatozoa). As the cell transitions through these life stages, it moves toward the lumenThe inside space of a hollow organ or structure. of the seminiferous tubule where it disengages from the nurse cells of the seminiferous tubule and becomes free swimming.

Spermatids & Myoid Cells

Spermatids are not yet able to swim, owing to incomplete formation of their flagellaLong, whip-like structures used by some cells (e.g., sperm) for movement.. Because of this, seminiferous tubules are bounded by myoid cells, which are essentially smooth muscle cells. Much like the components of the digestive system, these myoid cells can generate something akin to peristalsis Rhythmic contractions of smooth muscle that move food through the digestive tract. to help move the spermatids toward the rete testis. These myoid cells can contract, moving spermatids along in the seminiferous tubules to the rete testis.

Rete Testis

I think of the rete testis as Penn Station in NYC…or Grand Central Station. Whatever your preference for entering Manhattan is, these stations are places where all trains and buses converge to exchange passengers. The rete testis collects all the spermatids from all the seminiferous tubules and distributes them to the epididymis, where they mature to spermatozoa and wait for ejaculation or where they get reabsorbed if not used.