New evidence of melatonin receptor contribution to ram sperm functionality.

The present study analysed the involvement of melatonin, acting via its receptors (MT and MT), in ram sperm functionality. Indirect immunofluorescence assays revealed no changes in the distribution or intensity of MT receptors, whereas different subpopulations were established for MT receptors in control, in vitro capacitated and acrosome-reacted ram spermatozoa. Chlortetracycline staining revealed the following correlations between the pattern of staining for MT receptors in: (1) non-capacitated (NC) sperm rate and the proportion of spermatozoa with equal immunostaining intensity in the acrosome and post-acrosome (r=0.