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|Type:||Artigo de periódico|
|Title:||Cytochemical study of spermiogenesis and mature spermatozoa in the lizard Tropidurus itambere (Reptilia, Squamata)|
|Abstract:||The present study was undertaken to detect essential components of spermatozoa by ultrastructural and cytochemical analyses of testis and epididymis of the lizard Tropidurus itambere at different points of its annual reproductive cycle. Cytochemical investigations of spermiogenesis have not been performed so far in Squamata and are scarce for lower vertebrates. Essential components are: 1) polysaccharides, identified by PAS staining, abundantly present in Sertoli cell elongations, acrosomal vesicles and the acrosome of sperm cells; 2) glycoconjugate variations, labeled by different lectins and used to investigate cell modifications during spermiogenesis and found in mature spermatozoa in the female's seminal receptacle; 3) basic proteins, present in large quantities in spermatozoa in the subacrosomal cone, the pericentriolar material, the midpiece dense bodies, the peripheral fibers of the axoneme, and the fibrous sheath of the flagellum; 4) the final reaction product of acid phosphatase activity in several stages of acrosome development, specifically in the clear zone and epinuclear electron-lucent region of spermatozoal acrosomes, as well as in very active lysosomes found during the quiescent period of the reproductive cycle; 5) lipids, abundantly present in the cytoplasm of Leydig cells during the quiescent period. The cytochemical methods show that the ultrastructurally complex acrosome is also biochemically heterogeneous, with specific layers rich in glycoproteins, basic proteins or acid phosphatase. These different components may play a role during sperm penetration into the ovule. Basic proteins are largely responsible for structures surrounding the axoneme to provide resistance to the flagellum. In the quiescent period, acid phosphatase activity is involved in the elimination of superfluous sperm cells, whereas lipids in Leydig cells are used for hormone synthesis which starts at this time point to initiate a new reproductive cycle. Variations in lectin staining revealing glycoconjugates show that spermatozoa undergo post-testicular maturation up to their storage in the female.|
|Editor:||Urban & Fischer Verlag|
|Appears in Collections:||Unicamp - Artigos e Outros Documentos|
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