SPERMATOZOA SUBPOPULATIONS IN BUCK BASED ON HEAD AND TAIL MORPHOMETRIC PARAMETERS

The knowledge that spermatozoa differ in morphological and functional characteristics has initiated studies in order to isolate subpopulation of spermatozoa with better functional abilities. The aim of this study was to determine spermatozoa subpopulations based on morphometric parameters of spermatozoa head (MPSH) and tail (MPST) in ejaculates of bucks (N=12) over a period of 3 months. Semen smears were prepared and stained with method of Bloom to establish the proportion of live spermatozoa. By using a computer assisted-image analyses system, morphometric measurements were performed (50 spermatozoa per smear) with the "SFORM" program. Morphometric data were collected for spermatozoa head, mid-piece and tail (area, outline, length, width), and for head shape (regularity, rugosity, ellipticity, elongation). By analyzing of principal components, two values were obtained explaining 85% of variance for MPSH and 78.5% for MPST. For MPSH, the 1st component focused on measurements of size and the 2nd on head shape. The 1st component for MPST focused on length and the 2nd on the width of the mid-piece. Cluster analysis of the most important parameters for each component revealed 4 spermatozoa subpopulations based on MPSH and MPST. The 1st subpopulation of MPSH comprised small sized spermatozoa with high rugosity spermatozoa (17%), the 2nd the biggest sized (4.8%), the 3rd elliptical and elongated (24.5%) and the 4th average sized spermatozoa (53.4%). The 1st spermatozoa subpopulation based on MPST comprised spermatozoa with the smallest size of the mid-piece (63.0%), 2nd spermatozoa with the widest mid-piece but the shortest tail (10.9%), the 3rd spermatozoa with the longest tail (21.6%) and 4th spermatozoa with the greatest length, area and outline of mid-piece (4.5%). Morphometric analysis of the principal components and cluster analysis, could provide data about semen quality and the freezing ability, according to the proportions of the individual subpopulations in the semen.