%0 Journal Article
%T Morphological Changes of Mammalian Nucleoli during Spermatogenesis and Their Possible Role in the Chromatoid Body Assembling
%A Rita Luiza Peruquetti
%A Sebasti£¿o Roberto Taboga
%A Maria Terc¨ªlia Vilela de Azeredo-Oliveira
%J ISRN Cell Biology
%D 2012
%R 10.5402/2012/829854
%X Chromatoid body (CB) is a typical cytoplasmic organelle of germ cells, and it seems to be involved in RNA/protein accumulation for later germ-cell differentiation. Despite most of the events in mammals spermatogenesis had been widely described in the past decades and the increase in the studies related to the CB molecular composition and physiology, the origins and functions of this important structure of male germ cells are still unclear. The aims of this study were to describe the nucleolar cycle and also to find some relationship between the nucleolar organization and the CB assembling during the spermatogenesis in mammals. Cytochemical and cytogenetics analysis showed nucleolar fragmentation in post-pachytene spermatocytes and nucleolar reorganization in post-meiotic spermatids. Significant difference in the number and in the size of nucleoli between spermatogonia and round spermatids, as well as differences in the nucleolar position within the nucleus were also observed. Ultrastructural analysis showed the CB assembling in the cytoplasm of primary spermatocytes and the nucleolar fragmentation occurring at the same time. In conclusion our results suggest that the CB may play important roles during the spermatogenesis process in mammals and that its origin may be related to the nucleolar cycle during the meiotic cell cycle. 1. Introduction Spermatogenesis is the biological process of gradual transformation of germ cells into spermatozoon over an extended period of time within the boundaries of the seminiferous tubules of the testis. This process involves cellular proliferation by repeated mitotic divisions, duplication of chromosomes, genetic recombination through crossover, reduction division by meiotic cell division to produce haploid spermatids, and terminal differentiation of the spermatids into spermatozoon [1]. This important biological process has been extensively studied and described, and currently there are appropriate biological terminologies to describe every step of the spermatozoon formation [2]. However, there are some recent important aspects of the spermatogenesis, as, for example, the assembling and the function of the chromatoid body (CB), which is not so clearly understood. The CB is a typical cytoplasmic organelle of haploid germ cells and is involved in RNA and protein accumulation for later germ-cell differentiation [3, 4]. Many studies have been carried out intending to clarify the origins and functions of this intriguing cytoplasmic structure of male germ cells. Recent efforts to elucidate the functions of the CB have been
%U http://www.hindawi.com/journals/isrn.cell.biology/2012/829854/