Seminal characteristics and cryopreservation of sperm from the squirrel monkey, Saimiri collinsi

The Neotropical nonhuman primate squirrel monkey (Saimiri sp.) is one of the most commonly used species in research in several areas of knowledge. However, little progress has been reported in respect to techniques for preservation of their gametes. Thus, the main objectives of this study were (1) to describe testicular and seminal aspects of a new species, Saimiri collinsi, (2) to preserve semen of this species by cooling or freezing using ACP-118 (powdered coconut water), and (3) to test two glycerol (GLY) concentrations (1.5% or 3%) for semen freezing in the presence of ACP-118. The experimental group started with 14 captive males, but only 11 were suitable to collect ejaculates containing sperm. After anesthesia, both testes were evaluated: length, width, height, and testicular circumference. Semen was collected by electroejaculation and evaluated, followed by dilution, cooling, and freezing. Seminal parameters and sperm motility, vigor, plasma membrane integrity, and normal morphology were evaluated after each step; functionality was also checked in fresh and frozen-thawed sperm. Sperm motility, plasma membrane integrity, and normal sperm in cooled semen (n = 11) were 44.1 ± 34.0, 63.1 ± 15.6, and 73.8 ± 19.8, respectively, with vigor ranging of 2 to 3. Sperm motility, plasma membrane integrity, normal and functional sperm in frozen semen (n = 5) were 0.6 ± 1.3 (1.5% and 3% GLY); 4.4 ± 4.9 (1.5% GLY) and 6.6 ± 7.2 (3% GLY); 86.8 ± 3.0 (1.5% GLY) and 88.8 ± 5.1 (3% GLY); 13.3 ± 11.9 (1.5% GLY) and 14.3 ± 13.5 (3% GLY), respectively, and vigor 0 for both 1.5% and 3% GLY. No significant difference between GLY concentrations was observed. We concluded that electroejaculation was efficient for semen collection of S collinsi and tested the cooling protocol that allowed to recover a satisfactory percentage (63%) of membrane intact sperm. However, the freezing protocol was not appropriate to sperm preservation.