Morphology and chromatin condensation evaluation in fowl spermatozoa (Gallus gallus, Linnaeus, 1758) through the transmission electron microscopy

Abstract

The spermiogram is one of the principal methods of evaluation of the fertility in mammals; however some semen modifications as the spermatozoa chromatin condensation, are not identified in this routine, and can expressively interfere in the fertility of reproducers. In poultry breeding, generally the evaluation of reproducers is made by sampling and the evaluated parameters are in fewer quantities than in mammals, considering the spermatozoa chromatin condensation of the fowl has never been exploited. The objective of this work is verifying through the transmission electron microscopy, whether there are different intensities of spermatozoa chromatin condensation of fowl. So that, have been collected 20 samples of fowl semen, which were placed in 4% glutaraldehyde buffered in 0.1M sodium cacodilate to pH 7.2 for 48 hours, after being centrifugated and rinsed in cacodilate tampon, the semen was post-fixed in 1% osmium tetroxide plus 1.25% potassium ferrocyanide. The sediment was embedded, cut and contrasted. The thin sections were examined and documented in transmission electronic microscopy Zeiss EM-109. Generally the fowl spermatozoon has acrosome with homogenic or slightly granular and of moderate density material, the nucleus with dense or slightly granular chromatin, varies the gray scales, that is, the grades of condensation. It was also observed the "perforatorium", structure that links the nucleus to the acrosome. The insertion of the tail is made through two cetriules, being one transversal and the other longitudinal to the axle. The intermediate piece has typical axoneme involved by mitochondrias, apparently displayed longitudinally. The transition between the principal and the intermediate pieces of the tail is marked by the absence of the mitochondrias. The principal piece is formed by axoneme involved by a granular cytoplasm layer. In the evaluation of the morphological pathologies, it was observed rounded heads, folded, involved by the intermediate container of the piece, in a hook and all of them showing different grades of condensation.