USE OF A SIMPLE STAINING TECHNIQUE TO DISTINGUISH ACROSOMAL CHANGES IN THE LIVE SPERM SUBPOPULATION

In order to determine acrosomal status in live spermatozoa, the two co mmon staining techniques, nigrosin-eosin (NE) stain and the Giemsa sta in, were combined. There was no significant difference between proport ions of live boar spermatozoa determined by the NE technique and the n igrosin-eosin-Giemsa (NEG) technique. The proportion of live spermatoz oa determined by the NEG technique was also compared with the results of fluorescent viability stains, carboxyfluorescein diacetate and prop idium iodide. The difference, although significant (P<0.01) was small, 87% (NEG) vs. 80% (CFDA/PI). With ram semen, samples were compared fo r proportions of live cells and the NEG technique gave six percentage points lower than the NE technique (P<0.01). Acrosomal alterations, de termined by differential interference contrast microscopy and by the N EG technique did not differ significantly for boar or ram spermatozoa. This novel staining technique is capable of determining four categori es of spermatozoa: live acrosome-intact, live acrosome-reacted or dama ged, dead acrosome-intact and dead acrosome-reacted or damaged. The me thod is simple to perform, requires only basic equipment and appears e xtremely reliable.