The fine structure of the monkey (Macaca) Sertoli cell and its role in maintaining the blood-testis barrier.

Abstract

AbstractThe monkey Sertoli cell, a tall columnar cell, extends from the basement membrane of the seminiferous epithelium to the tubule lumen. Its nucleus occupies a basal position and reveals extensive nuclear envelope infoldings. A zone of fine filaments, approximately 0.5 μ in thickness, invests the nucleus and appears to prevent other cell organelles from approaching it. The basal cytoplasm is characterized by numerous mitochondria and abundant smooth endoplasmic reticulum. Lipid droplets, 3 to 4 μ in diameter, membrane‐limited dense bodies of various shapes and densities, Golgi cisternae, scattered free ribosomes and parallel profiles of rough endoplasmic reticulum are common. The more apical portions of the cell contain longitudinally oriented microtubules and rod‐shaped mitochondria, but other organelles are rare.The seminiferous tubules of monkeys are surrounded by three to five circumferentially arranged cells that overlap each other but are separated by intercellular spaces of at least 300 to 400 Å. Tracers such as horseradish peroxidase and lanthanum nitrate injected intravascularly readily pass between the peritubular cells and enter the germinal epithelium. Within the epithelium the tracers outline the spermatogonia and early spermatocytes by permeating the surrounding intercellular spaces. Further penetration toward the tubule lumen is effectively prevented by the occluding tight junctions joining adjacent Sertoli cells. Thus, in monkeys the peritubular epithelioid cells do not impede vascularly introduced tracers from penetrating into the germinal epithelium. The only morphological component of the blood‐testis barrier in the macaque appears to be the Sertoli‐Sertoli occluding junction.