143 The Dynamics of Spermatogenesis in Guinea Fowls

Male gonads are valuable genetic material for creation of biomaterial cryobanks to preserve the genes of various animals, including poultry. Spermatogonia, which are stem cells of the testes, are of greatest interest. For effective selection of spermatogenic cells, including spermatogonia, it is necessary to know the specific features of spermatogenesis of the species of interest. In this regard, the aim of this study was to investigate the dynamics of spermatogenesis in guinea fowl. Histological examinations of guinea fowl testes (n=90 birds) were done for 9 age categories, from 2 wk to 6 months. For each individual, at least 30 seminiferous tubules were examined. Seminiferous tubule diameters and numbers and types of spermatogenic cells (based on morphology) were determined. Overall, the histologic structure of guinea fowl testes was similar to that of mammals. Cell populations of the seminiferous tubules included Sertoli cells and generative cells, including spermatogonia, spermatocytes, spermatids, and sperm, at various stages of differentiation. Diameter of seminiferous tubules was (mean±SEM) 36±1, 58±1, 64±1, 65±1, 110±3, 178±4, 233±4, 274±6, and 295±5µm at 2 wk, 1, 1.5, 2, 2.5, 3, 4, 5, and 6 months, respectively. Furthermore, at those ages, the number of spermatogenic cells per tubule was 18±1, 20±1, 29±2, 30±2, 68±5, 114±8, 186±10, 400±20, and 447±24. Maximum percentage of spermatogonia was 72±2% at 6 wk. Primary and secondary spermatocytes were first observed at 10 and 12 wk of age, respectively, whereas spermatids were first apparent at 4 months. Sperm were first identified at 5 months, with more present at 6 months. We concluded that the optimal age for retrieving testicular germ cells in guinea fowl was no later than 8 wk, as that represented the age when seminiferous tubules were dominated by spermatogonia. The study was supported by the Russian Science Foundation (Project no.16-16-04104).