The Sertoli cell of the water buffalo (Bubalus bubalis) during the spermatogenic cycle

Summary Ultrastructural features and morphometric evaluations of buffalo Sertoli cells are reported for the six phases of the spermatogenic cycle. The phases of the tubular seminiferous epithelium are identified according to characteristic cellular associations with completed spermiation as demarcation between two cycles. Average tubular diameter (245 m) and epithelial height (61 m) do not vary significantly during the cycle. The relative Sertoli cell volume in the seminiferous epithelium varies between 30% (phase 4) and 39% (phase 8). The calculated volume of a single Sertoli cell increases from a nadir of 7118 m³ in phase 3 abruptly to a maximum of 8968 m³ in phase 4 and is then gradually reduced during the following phases. The Sertoli cell surface area shows a similar trend: it amounts to 11105 m² in phase 3 and to 14260 m² in phase 4. The contact area of the Sertoli cell with adjacent cells and structures is subject to characteristic changes; from the expansion of basal Sertoli-Sertoli contacts it is concluded that the blood-testis barrier in the buffalo is particularly tight during phases 8, 1 and 2. The irregularly contoured nucleus contains a vesicular nucleolus, has a calculated volume from 465 m³ to 543 m³ and occupies 5 to 7% of the cell. Volume percentages of mitochondria (4%), Golgi apparatus and lysosomal bodies are rather constant during the cycle. Whorls and orderly arranged aggregates of the smooth endoplasmic reticulum occur in basal location as well as in close association with elongating spermatids. Smooth ER is the organelle that exhibits the most prominent changes during the Sertoli cell cycle: it occupies 5.79% in phase 3 and 20.9% in phase 4 of the total cellular volume. Phagocytosis of residual bodies is insignificant in this species and a lipid cycle is absent in buffalo Sertoli cells.