Homogenization-resistant spermatids in testicular tissue stored under suboptimal conditions-Effect of time and temperature.

Reproductive assessments on wild animals are often hampered due to practical problems during sample collection. For example, the time between death and tissue collection as well as sample storage conditions will affect the quality of the tissue. The aim of this study was to examine the effect of less optimal, field-like conditions, that is different temperatures and variable storage time, on the quantification of homogenization-resistant spermatids in testicular tissue, using the bull as a model. One bull testis was kept in +5°C for 216 hr, from which (n = 68) samples were taken at different time points for storage in -20°C or +21°C. Some samples were frozen, thawed and then refrozen. The tissue was homogenized, and the number of spermatids was quantified manually with a counter chamber. Compared to the samples taken at 0 hr, the number of spermatids was unchanged until 120 hr storage in +5°C and in frozen samples from the same time-point. After 72-hr storage in room temperature, there was a marked drop in the number of spermatids. Refreezing of samples resulted in a markedly lower number of spermatids. Frozen samples did not have significantly decreased numbers of spermatids compared to refrigerated samples. In conclusion, different storage conditions do not seem to affect the spermatids resistance to homogenization until day 3, but if kept in cool conditions it is possible to use samples up until 5 days of storage. The method is a good choice for suboptimal sampling conditions.