Efeito do processo de sexagem de sêmen por citometria de fluxo e crioprervação sobre a morfometria da cabeça de espermatozóides e estabilidade de cromatina

Abstract

Bovine sexed semen has been commercially evaluated due to its great economic value for sex selection in milk and beef cattle raising, with purity around 90% for the desired sex. However, its employment depends on the cryopreservation use. The objective of the present study was to analyze the spermatic chromatin stability and morphometric alterations in spermatozoid heads from semen-donor bulls through computerized images obtained from microscopic slides of in natura sexed semen stained with toluidine blue, unfrozen sexed semen and from unfrozen conventional semen. Seventeen ejaculated from 17 bulls were used in the confection the microscopic slides for the morphometric analysis of the spermatic head and 15 ejaculated from 15 bulls were used for the analysis of the spermatic chromatin stability. One hundred digital images were obtained from each slide and were used to segment 100 spermatozoid heads from each slide. Area (A), perimeter (P), width (W), length (L), width/length ratio (W/L), elipcity (E), shape factor (SF), lateral symmetry (LS) and anterior-posterior symmetry (APS) of all heads were determined through the use of softwares developed in the SCILAB. Fourier descriptors with amplitude from 0 to 2 (F0, F1, F2) were also considered for the characterization and analysis of shape, and the spermatic chromatin was evaluated in relation to compaction intensity and homogeneity. Based on results obtained, the dilution, staining and incubation process previous to the separation process through flow cytometry and cryopreservation influenced the morphometry of spermatic cells; however, the chromatic compaction was slightly affected by the sexed process through flow cytometry.