Morphometric features and chromatin condensation abnormalities evaluated by toluidine blue staining in bull spermatozoa

ABSTRACT

In this article, we investigated the correlation between the morphometric features of sperm heads and abnormalities in chromatin condensation using computational image analysis of sperm smears stained with toluidine blue. The chromatin structure was characterized in terms of the average gray-level intensity and the corresponding coefficient variation based on images of the head. The geometry of the sperm heads was determined based on several morphometric measurements, including the area, perimeter, width, length, width length ratio, ellipticity, shape factor, Fourier descriptor and symmetry. The correlation between the chromatin structure and the geometrical properties was evaluated. The correlation coefficients between the morphometric features and chromatin alterations varied substantially from sample to sample, although a normal morphology was found in heads with or without abnormalities in chromatin condensation. Variations in the abnormalities in chromatin condensation influenced the head morphology in different ways. The finding that spermatozoa with chromatin abnormalities did not necessarily show morphological alterations demonstrates the need for the morphological analysis of sperm to be followed by an evaluation of chromatin structure.