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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.

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The present study aimed to obtain quanti-qualitative data about the follicular ovarian population in Cebus apella females. Seven ovaries were obtained from 4 C. apella adult females. The ovaries were subjected to light microscopy. The number of preantral and antral follicles for each ovary was estimated using the Fractionator method. The preantral follicles were classified into primordial, transitional, primary and secondary follicles. Antral follicles were those that presented an antral cavity. All counted follicles were classified as normal or degenerated. The diameter of the follicles, oocytes and their nuclei were determined to accompany the follicular development. All results were represented as mean ± SE. The number of preantral follicles was 56,938 ± 21,888 and 49,133 ± 26,896 for the right and left ovaries, respectively. The percentage of normal follicles was 80 ± 4.95%. The follicular diameter ranged from 22 ± 0.5 Fm to 61.2 ± 4.0 Fm. Regarding the antral follicles, the number of normal and degenerate follicles per ovary were 60.0 ± 19.0 and 3 ± 1.8 follicles, respectively. The antral follicular diameter was 514.4 + 56.6 Fm. In conclusion, the information obtained in this study can be used as a parameter for subsequent in vivo or in vitro studies about folliculogenesis in non-human neotropical primates of the C. apella species. KEY WORDSOvary, histological study, Cebus apella, ovarian follicles. Estudo histológico de folículos ovarianos de Cebus apella. RESUMO PALAVRAS-CHAVEOvário, estudo histológico, Cebus apella, folículos ovarianos.

Germoplasm banking is an important tool for the preservation of genetic material from Neotropical primates in captivity, and from free living species, especially the endangered ones like Saimiri vanzolinii (Black-headed squirrel monkey), a primate with a low incidence area (870 km(2) of floodplains) in the southern part of the Mamirauá Sustainable Development Reserve, Brazil. Therefore, in the present study we aimed to develop a sperm cryopreservation protocol comparing sperm cooling in presence (T1) and absence (T2) of egg yolk, and to test freezing protocols to preserve semen from captive (Saimiri collinsi), and free-living (Saimiri vanzolinii, Saimiri cassiquiarensis and Saimiri macrodon) New World primates. Cooling preserved sperm of S. collinsi in all evaluated microscopic parameters, except for sperm motility. No differences were observed among the treatments, indicating that semen of this species can be cooled without egg yolk. Freezing did not affect sperm quality of S. collinsi, except plasma membrane integrity that was negatively affected. Generally, a good maintenance rate was observed between cooling and thawing of semen for the four species, showing the positive translational application of protocols from S. collinsi to the free-living species. Developed freezing protocol proved to be useful for sperm cryopreservation of S. collinsi and in field conditions.

Differential phenotypic characteristics for taxonomic diagnosis purposes are well determined in the genus Saimiri (squirrel monkey). However, data on its reproductive characteristics are lacking. Our aim was to determine testicular biometry and correlate with seminal analysis in captive (Saimiri collinsi) and free living (Saimiri vanzolinii, Saimiri cassiquiarensis, and Saimiri macrodon) squirrel monkeys. Testicular length, width, height, circumference, and volume were measured. Testicular biometry showed no differences between right and left testicles within the same species, as well as among species. Semen collected by electroejaculation was constituted of a liquid and coagulated fraction, or only one of them. No significant difference was observed between mean volumes of liquid (49.2 ± 68.9 μL: S. collinsi; 28.3 ± 59.8 μL: S. vanzolinii; 5 ± 7.1 μL: S. cassiquiarensis; and 0 μL: S. macrodon) and coagulated (65.4 ± 142.1 μL: S. collinsi; 125.8 ± 142.5 μL: S. vanzolinii; 175 ± 176.8 μL: S. cassiquiarensis; and 500 μL: S. macrodon) fractions within species or when each fraction was compared among the studied species. No correlation between testicular volume and seminal volume was observed when liquid (R = 0.31, S. collinsi; R = -0.69, S. vanzolinii) and coagulated (R = 0.32, S. collinsi; R = -0.37, S. vanzolinii) fractions were evaluated. No sufficient data were obtained for the other two species. Seminal quality was similar among species, and the most common defect was coiled tail. The method of electroejaculation yielded satisfactory results on these species, under field conditions.

The aim of this study was to evaluate ovarian tissue pre-treatment with 50 µM Trolox followed by heterotopic transplantation in squirrel monkeys (Saimiri collinsi) and to assess tissue functionality via immunohistochemical analysis of the stroma and ovarian follicles. Five healthy and sexually mature squirrel monkey (Saimiri collinsi) females were used. Heterotopic autografting of fresh ovarian tissue with or without previous exposure to the antioxidant Trolox was performed and grafts were recovered for analysis 7 days later. Tissue vascularisation was confirmed by both macroscopic inspection and cluster of differentiation 31 (CD31) staining. Trolox prevented massive follicular activation and kept the percentages of morphologically normal follicles higher than in untreated grafts. Expression of anti-Müllerian hormone in developing follicles was observed only in controls and Trolox-treated grafts. Also, immunostaining for growth differentiation factor-9 was positive only in primordial follicles from controls and from Trolox-treated grafts. Although Trolox improved follicular quality and avoided apoptosis in stromal cells, ovarian tissue fibrosis was increased in Trolox-treated grafts, mainly due to an increase in collagen Type I synthesis.