Scanning electron microscopy of the adult human testis

Scanning electron microscopy was performed on adult human testicular tissue using fresh orchiectomy and some recent autopsy material. After preliminary fixation in 2.5% glutaraldehyde in phosphate buffer, pH 7.4, blocks were taken for scanning electron microscopy and for correlative light and transmission electron microscopy,. For scanning electron microscopy, the tissue was processed by means of the osmium-thiocarbohydrazide-osmium method, dehydrated and critical point dried with CO2. Blocks taken from the periphery of the testis showed the presence of the tunica albuginea, which formed a comparatively dense encapsulation around the testis. Large blood vessels were present at points along the innermost layer of the tunica. Within the testis, the vessels became progressively smaller and came into close apposition to the seminiferous tubules. Individual tubules could be identified from the lowest magnification (15x). They were seen both as intact, intricately convoluted structures and at all levels and planes of transection. Within the tubules, the seminiferous epithelium was seen both in the intact and transected state. All of the cell types, were identified. In the basal layer, in contact with the basement membrane, there were spermatogonia and varying numbers of Sertoli cells. Spermatocytes were located in the mid-zone of the tubule and spermatids in the adluminal compartment. There were numerous tails of spermatozoa projecting into the lumen. Normal spermatozoa, some round headed forms and an occasional bizarre multiheaded spermatozoon were observed. Leydig cells were noted in the intertubular angles and in close proximity to blood vessels.