AN ULTRASTRUCTURAL AND LECTIN-HISTOCHEMICAL STUDY ON THE SEMINIFEROUSEPITHELIUM OF THE COMMON TREE SHREW (TUPAIA-GLIS)

The seminiferous epithelium of the common tree shrew (Tupaia glis) was investigated using transmission electron microscopy and lectin-histoc hemistry. It was compared with that of shrews examined in previous stu dies. Some peculiar structures were detected in the tree shrew spermat id at the electron microscopic level. The most characteristic feature was the disposition of mitochondria in early spermatids. In cap and ea rly acrosome-phase spermatids, mitochondria accumulated in one area of the spermatid cytoplasm and then dispersed in the late acrosome phase . Subsequently they again clustered to form the middle piece of sperma tozoa. While the lamellar structure was clearly seen in the caudal reg ion of the spermatid nucleus, it gradually disappeared during the proc ess of elongation. The dilated area in the postacrosomal space of earl y round spermatids was also characteristic. The dilation was not detec ted in elongated spermatids. These structures were not recognised in t he seminiferous epithelium of shrews. With respect to lectin histochem istry, the binding patterns in the spermatid acrosome of the tree shre w were similar to those of the musk shrew. However, PNA and BPA, which reacted with the Sertoli cell cytoplasm of the musk shrew, showed no reaction in the tree shrew Sertoli cell. Thus, except for some lectin binding patterns in the spermatid acrosome, no close similarity was re cognised in the morphology of the seminiferous epithelium between tree shrews and shrews.