This study analyzes the development of spermatogenesis in peccaries (Tayassu tajacu) and establishes the age the reach puberty, considering testicular biometry and seminiferous tubules, the amount of spermatogenic cells, the morphological description of the stages of the seminiferous epithelium cycle (SEC), the relative frequency on which they surge inside the seminiferous tubules and general spermatogenesis yield. In the experiment, the animals were divided according to age bracket, into five groups, with three animals in each group, G1 (7 to 8 months), G2 (9 to 10 months), G3 (11 to 12 months), G4 (13 to 14 months) and G5 (15 to 16 months). The animals were subjected to orchiectomy surgery, to obtain the testicle samples, which were fixed in Alfac solution for 24 hours and histologically processed, where 5 μm cuts were stained in hematoxylin eosin. Based on the tubular morphology method, it was done the quantification of the cell types corrected to its average nucleus diameters of 10 transversal sections at SEC stage 1 for animals with established spermatogenesis and 20 transversal sections for the younger animals without any established spermatogenic activity; and also the classification of the stages of the seminiferous epithelium cycle, by analyzing 100 transversal sections of seminiferous tubules. The data from the testicular biometry, such as, weight, length and width, showed gradual and constant growth with significant statistical differences (p<0,05) and high correlation among themselves. The tubular diameter values presented statistical significance from G1 to G4, and from G4 an accelerated and continuous growth, with no statistical significance (p>0,05). According to the quantitative and morphological analysis of the spermatogenic cells which form the germinative epithelium, the animal age brackets were classified in the following phases impuberal (G1), prepuberal (G2), puberty (G3), pos puberty 1(G4), and pos puberty 2 (G5). The phase the productive activity started, or, puberty, was determined in the animals when they turned 11 months, when the the greatest growth in the number of spermatogenic cells and a positive correlation with testicular weight occurred. At this stage, the Sertoli cells, presented a significant decrease (p<0,05). During determination of relative frequency of the stages of seminiferous epithelium cycle, eight types of association were observed, according to the tubular morphology method, where the stages with greater and less frequency were 1 and 3 respectively. The pos meiotic phase showed more frequency and the meiotic phase, the lower one, being statistically significant in relation to the other ones. The reproductive efficiency was demonstrated through translated values by the cell ratios between type A spermatogonic cells and round spermatids, being that no significant increase between G3, G4 and G5 was observed (p>0,05); and the rate of Sertoli cells showed a significant statistical difference between all possible comparisons of age brackets from G3 to G5 (p< 0,05).
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