Resumen de Los espermatozoides bovinos con cromatina alterada están distribuidos morfométricamente en distintas subpoblaciones

H. Nava, A. Quintero Moreno

• The aim of this study was to identify and characterize the morphometrically distinct sperm subpopulations (SP) stained with toluidine blue (AT) and to determine how sperm with damaged chromatin (DC) are distributed in each SP. To this, sperm of fifteen cryopreserved ejaculates from Brahman bulls were stained with AT, chromatin integrity status was determined to each sperm and simultaneously sperm head morphometry was determined using a CASMA software. Posteriorly statistical analysis to determine the number of sperm morphometrically distinct SP according to morphometric parameters (length, width, area and perimeter) was carried-out and the distribution of sperm with DC in each SP was evaluated. A total of 2273 sperm were analyzed, 70.35% with normal chromatin and 29.65% with DC. CLUSTER analysis identified three SP, smallest sperm-head (SP1) with 6.29%, intermediate sperm-head (SP2) with 60.54% and biggest sperm-head (SP3) with 33.17%. Percentage of sperm with damaged chromatin was lower (P<0.05) in SP2 (20.58%) in comparison with SP1 (53.15%) and SP3 (42.31%). In conclusion, cluster analysis identified three morphometrically SP in bull semen, and sperm with DC were presented in these SP, but SP2 had lowest percentage of sperm with DC, suggesting that this SP has more stable chromatin.