Comparison of different chromatin staining techniques for bull sperm

Morphological analysis of semen is a very important step in fertility assessment, but many semen defects are not detectable at the morphological level. These include pathological changes in sperm chromatin structure. During mammalian spermiogenesis, histone proteins associated with DNA structure are replaced by specific protamines, with which chromatin does not form nucleosomal complexes. In the fully developed, mature sperm, the histones are replaced with protamines. Disruptions of nucleoprotein structure can be treated as possible indicators of the biological value of spermatozoa. The experimental material consisted of sperm from one-and-a-half-year-old bulls, isolated post mortem from the tail of the epididymis. The smears were stained with silver nitrate (AgNO3), acridine orange (AO), aniline blue (AB) and chromomycin A3 (CMA3). Sperm dimensions largely depend on individual variability among the bulls. In most cases, differences in sperm dimensions were identified between individuals, which was confirmed in the statistics. Sperm with elevated, abnormal histone levels were proportionally quite scarce (1.4 %). Studies of nuclear proteins in the context of infertility demonstrate the important influence of normal chromatin structure on sperm functions.