Delgadillo J A, Hochereau-de Reviers M T, Daveau A, Chemineau P
Universidad Autónoma Agraria Antonio Narro, Carretera a Santa Fé y Periférico, Torreón, Coahuila, Mexico.
Reprod Nutr Dev. 1995;35(5):549-58. doi: 10.1051/rnd:19950507.
This study was performed in adult male goats in which seasonal variations were abolished by rapid alternations of long days and short days. These treatments have been shown previously to prevent seasonal changes in the hypothalamo-pituitary axis and to maintain testis weight and sperm production at a high level. The experimental groups were exposed for 3 years to an alternation of either a 1 month short (16 h dark; 8 h light) and 1 month long (16 L; 8 D) photoperiod (2 month cycle; n = 5) or of a 2 month short and 2 month long photoperiod (4 month cycle; n = 4). The control groups were maintained in natural photoperiodic conditions (45 degrees N) and goats were slaughtered in the non-breeding season (end of April RS; n = 5) at the same period as light-treated bucks, or in the breeding season (end of September BS; n = 6). The total weight of the testes, the length and mean diameter of the seminiferous tubules of light-treated goats were similar to those in the breeding season, and higher than those in the non-breeding season. The total number of A0 spermatogonia was increased by light treatments as compared to control goats in the breeding and non-breeding season. The daily production of A1 spermatogonia, leptonene primary spermatocytes and round spermatids in light-treated goats was maintained at the peak breeding season level. The intra-testicular concentration of testosterone, total volumes of intertubular tissue and of Leydig cells, and the number of Leydig cells per testis did not differ between groups. Although the mean cross-sectional area of Leydig cells in light-treated goats was similar to this area in non-breeding season goats, it was significantly lower than that of breeding season goats. In conclusion, the rapid alternation of short and long days allowed an increase in all the germ cells from the A0 spermatogonia onwards, which was responsible for the maintenance of high spermatogenetic activity of light-treated goats.
本研究在成年雄性山羊中进行，通过快速交替长日照和短日照消除了季节性变化。先前已表明，这些处理可防止下丘脑 - 垂体轴的季节性变化，并使睾丸重量和精子产生维持在较高水平。实验组连续3年暴露于1个月短日照（16小时黑暗；8小时光照）和1个月长日照（16小时光照；8小时黑暗）的光周期交替中（2个月周期；n = 5），或2个月短日照和2个月长日照的光周期交替中（4个月周期；n = 4）。对照组维持在自然光周期条件下（北纬45度），山羊在非繁殖季节（4月底，RS；n = 5）与接受光照处理的雄鹿在同一时期宰杀，或在繁殖季节（9月底，BS；n = 6）宰杀。接受光照处理的山羊的睾丸总重量、生精小管的长度和平均直径与繁殖季节的相似，且高于非繁殖季节的。与对照组山羊相比，在繁殖和非繁殖季节，光照处理使A0精原细胞的总数增加。接受光照处理的山羊中A1精原细胞、细线期初级精母细胞和圆形精子细胞的每日产生量维持在繁殖旺季水平。各组间睾丸内睾酮浓度、管间组织和间质细胞的总体积以及每个睾丸的间质细胞数量没有差异。虽然接受光照处理的山羊间质细胞的平均横截面积与非繁殖季节山羊的相似，但显著低于繁殖季节山羊的。总之，短日照和长日照的快速交替使从A0精原细胞开始的所有生殖细胞数量增加，这导致了接受光照处理的山羊维持较高的生精活性。
