Spermiogenesis and chromatin condensation in the common tree shrew, Tupaia glis

Abstract

We have investigated the cellular characteristics, especially chromatin condensation and the basic nuclear protein profile, during spermiogenesis in the common tree shrew, Tupaia glis. Spermatids could be classified into Golgi phase, cap phase, acrosome phase, and maturation phase. During the Golgi phase, chromatin was composed of 10-nm and 30-nm fibers with few 50-nm to 60-nm knobby fibers. The latter were then transformed into 70-nm knobby fibers during the cap phase. In the acrosome phase, all fibers were packed into the highest-order knobby fibers, each about 80-100 nm in width. These chromatin fibers became tightly packed in the maturation phase. In a mature spermatozoon, the discoid-shaped head was occupied by the acrosome and completely condensed chromatin. H3, the core histone, was detected by immunostaining in all nuclei of germ cell stages, except in spermatid steps 15-16 and spermatozoa. Protamine, the basic nuclear protein causing the tight packing of sperm chromatin, was detected by immunofluorescence in the nuclei of spermatids at steps 12-16 and spermatozoa. Cross-immunoreactivity of T. glis H3 and protamine to those of primates suggests the evolutionary resemblance of these nuclear basic proteins in primate germ cells.

Seasonal evaluation of spermatogenesis of the hematophagous bat Desmodus rotundus in the Caatinga biome

“…The ultrastructural analysis of the cells that make up the stage 1 of the SEC was shown to be similar to that observed in other bat species [49][50][51][52]. During spermiogenesis, some unique events occur, including the formation of the acrosome, the condensation of nuclear chromatin, the elimination of residual cytoplasm and the development of the flagellum [53]. Although this process is similar in most animals, in D. rotundus the pro-acrosome vesicles containing electrodense materials were not observed, which may be related to the absence of a perforatorium, the structure responsible for penetrating the oocyte [54]; therefore, that these electron-dense materials can be the basic substance of their structural organization.…”

Ultrastructural characteristics of spermatogenesis in Pallas's mastiff bat, Molossus molossus (Chiroptera: Molossidae)

“…The process of acrosome formation in M. molossus is similar to that found in other mammals; the acrosome is formed by proacrosomal vesicles that already contain an electron‐dense granule (Kurohmaru et al,1994; Segatelli et al,2000; Suphamungmee et al,2008); however, it differs from that found in P. lineatus , which produces two different types of proacrosomal vesicles (Beguelini et al,2011a). On the other hand, the many wavy acrosomal projections on the acrosomal surface that we found in M. molossus seems to be rare.…”

Ultrastructure of spermatogenesis in the short-tailed fruit bat,Carollia perspicillata(Chiroptera: Phyllostomidae: Carollinae)

“…The process of acrosome formation in C. perspicillata seems to be similar to that found in P. lineatus (Beguelini et al, ), with the acrosome formed by two different types of proacrosomal vesicles, one electron‐dense and other electron‐lucid, but with none of them showing an electron‐dense granule inside. This pattern seems appropriate, because both species belong to the same family (Phyllostomidae); however, it differs from other mammals, where the acrosome is formed by proacrosomal vesicles that already contain an electron‐dense granule (Kurohmaru et al, ; Segatelli et al, ; Suphamungmee et al, ), and from other species of bats: from M. molossus that present the mammal pattern (Beguelini et al, ), and from Myotis nigricans that does not have electron‐dense secretions in its proacrosomal vesicles (Vespertilionidae; Beguelini et al, ).…”