147 Dynamics of drake spermatogenesis

Abstract

The examination of age dynamics for the development and differentiation of spermatogenic cells is of great importance to the study of spermatogenesis in poultry. Testicular stem cells, represented by spermatogonia, are a valuable genetic material for creating cryobanks of biomaterial. This is especially important when preserving and maintaining the gene pool of valuable breeds of poultry. In the process of differentiation, these cells give rise to a significant population of germ cells, so they can be used as donor cells for transplantation into the testes of male recipients. Thus, understanding species-specific characteristics of spermatogenesis in males is an important step for obtaining the spermatogenic cell population of interest. The aim of this research was to study the dynamics of spermatogenesis in drake. For the study, 10 groups of males were formed depending on age: 2 weeks and 1, 1.5, 2, 2.5, 3, 4, 5, 6, and 7 months. There were eight males in each age group from 2 weeks to 6 months and six males in the 7-month age group. The testes were isolated postmortem, fixed in Bouin's fixative solution, and embedded in paraffin, and histological sections (5 µm) were cut. The following indicators were evaluated: diameter of the seminiferous tubules, types of spermatogenic cells in the seminiferous tubules, and the amount of these cells within seminiferous tubules. Statistical analysis was performed using a t-test in SPSS ver. 15.0 (IBM Corp.). The types of spermatogenic cells were identified by morphology, and no fewer than 30 seminiferous tubules were examined from each individual. The diameter of the seminiferous tubules in the drake testes increased with age. At the ages of 2 weeks and 1, 1.5, 2, 2.5, 3, 4, 5, 6, and 7 months, these indicators were 38 ± 2, 55 ± 2, 60 ± 2, 61 ± 3, 62 ± 2, 62 ± 4, 65 ± 2, 76 ± 3, 94 ± 5, and 163 ± 7 µm, respectively. This was due to an increase in the number of spermatogenic cells within the seminiferous tubules to 23 ± 1, 27 ± 1, 38 ± 1, 44 ± 2, 47 ± 3, 57 ± 2, 68 ± 2, 140 ± 5, 187 ± 7, and 466 ± 13 at the ages of 2 weeks and 1, 1.5, 2, 2.5, 3, 4, 5, 6, and 7 months, respectively. The presence, number, and ratio of the cell populations varied depending on age. At the ages of 1-12 weeks, the main cell types in the seminiferous tubules were Sertoli cells and spermatogonia. After the age of 4 months, primary spermatocytes began to appear in the seminiferous tubules. Secondary spermatocytes were visualised at 5 months of age, whereas spermatids could be detected at 6 months of age. Mature sperm cells were detected in the seminiferous tubules of drakes at the age of 7 months. Based on the data obtained, the following conclusion can be made: from 1-12 weeks of age, the generative cells of the seminiferous tubules in drakes are represented mainly by spermatogonia (P < 0.05). Therefore, this period can be considered optimal for obtaining testicular stem cells and carrying out manipulations with them.

This study was supported by the Russian Science Foundation within project no.16-16-04104.