CARACTERIZACIÓN MORFOMÉTRICA Y CLASIFICACIÓN DE LOS ESPERMATOZOIDES DE VICUÑA (Vicugna vicugna) USANDO EL SISTEMA ISAS® CASA-Morph

Abstract

The aim of the study was to determine the morphological and morphometric characteristics of the vicuña sperm (Vicugna vicugna), looking for possible subpopulations in its structure. Semen was collected by electroejaculation method from three adult male vicuñas weighing 50.33 ± 2.52 kg, once per animal. The volume, color and concentration, sperm morphology and morphometry were determined. The samples for the analysis of sperm morphology and morphometry were stained with Hemacolor®, and analyzed using the CASA-Morph, Integrated Semen Analysis System (ISAS®v1). Five forms of the vicuña sperm head were distinguished: normal, piriform, long, short and rounded. The morphometric parameters determined were the length, width, area, perimeter, ellipticity, elongation, regularity and rugosity of the vicuña sperm head, percentage of acrosome, head gray level, as well as the width, area, distance and angle of insertion of midpiece of the sperm. In relation to morphology, significant differences (P <0.05) were found in the percentage distribution of head shapes, with the normal shape (55.7%) being the majority and different from the other shapes. Significant differences (P <0.05) were found between animals in the morphometric variables of head, percentage of acrosome, ellipticity, rugosity, elongation and gray level; while the variables of the midpiece and regularity did not show differences (P> 0.05). The morphometric variables were distributed in four main components (PCA) called elongation, area, circularity and midpiece width, which explained 84.59% of the total variance. The cluster analysis determined five subpopulations (SP): SP1 grouped small cells of low length, width and area (18.8%); SP2 of sperm of large size, both in area and width of the head (17.38%); SP3 of rounded cells with high values of percentage of acrosome and head gray level (24.04%); SP4 of spermatozoa of intermediate size and elongated, with greater ellipticities and elongation (23.61%); and SP5 of cells of intermediate size and short, with low values of area and length (16.71%).