Structure of the Sertoli Cell

This chapter discusses the structure of the Sertoli cell. The total number of Sertoli cells establishes the upper limit of sperm production by the testis, and spermatogenic efficiency is highly correlated with Sertoli cell support capacity, which is the best indication of Sertoli cell function. Sertoli cell individual volume shows high variation in mammals, varying from approximately 2000–3000 μm 3 to 6000–7000 μm 3 in mammals already investigated. However, it is generally recognized that species in which Sertoli cell volume is high are those with the lowest spermatogenic efficiency. The volume density of Sertoli cells in the seminiferous epithelium also changes considerably in mammals and the mean figures range from approximately 15% in mice and rabbit. One of the first features of the Sertoli cell is the unique appearance of the nucleus and its tripartite nucleolus. The Sertoli cell nucleus is large (250–850 μm 3 ) and can take on several different shapes depending on the stage of the seminiferous cycle and age of development. From birth to adulthood, the nucleus is often elongated, extending toward the lumen, but there are definite changes in appearance as the testis matures. The early support cells of the seminiferous tubule are often called pre-Sertoli cells because the nuclear appearance differs from the adult form, yet in some species the pre-Sertoli cells still have the typical nuclear features of irregular shape and a prominent nucleolus.