Myoid cells of seminiferous tubules

Myoid cells of seminiferous tubules 

 

 

Definition : A peritubular myoid (PTM) cell is one of the smooth muscle cells which surround the seminiferous tubules in the testis

Ultrastructure: Myoid cells have a basal lamina and large numbers of actin filaments.

They also exhibit a significant amount of rough endoplasmic reticulum (rER), a feature indicating their role in collagen synthesis in the absence of typical fibroblasts.

Features:

1.     PTM cells are derived from mesonephric cells

2.     PTM cells are spindle shaped and

3.     They  form several thin elongated layers, approximately 5-7 cell layers, and surround Sertoli cells.

4.     Blood vessels and extensive lymphatic vasculature as well as Leydig cells are present external to the myoid layer.

5.     These are detected in the lamina propria of the seminiferous tubule and immunohistochemical studies have shown functional distinctions between these layers. The inner layers have been shown to express desmin, a smooth muscle phenotype, whereas the outer layers express vimentin, a connective tissue phenotype

Functions of myoid cells:  

1.     Rhythmic contractions of the myoid cells create peristaltic waves that help move spermatozoa and testicular fluid through the seminiferous tubules to the excurrent duct system.

2.     Peritubular myoid cells play a crucial role in the self-renewal and maintenance of the spermatogonial stem cell (SSC) population