Dynamique et tendances de la reproduction de la marmotte bobac dans la région d'Orenbourg. The moving forces and trends of reproduction of bobac (Marmota bobac) in Orenburg Province.

Résumé

Now the bobac distribution in South Ural foothills is restricted by the comparatively dissected relief of Obshchiy Syrt and Guberlinsky Mts. as well as more flat territory of Orsk Plain and Tobol Platean. Our investigations in 1980-l994 show that there are no continuous bobac settlements in Orenburg Province. The Orsk Plain is covered by boutans (rammed ground heaps near marmot holes), which relative age is about 3000 years. The research of age structure of bobac populations showed that duration of bobac life was more 8 years. Two and three-years old individuals prevailed among collected animals. According to the number of placental spots the average number of babies per one litter is six. The maximal depression of spermatogenesis is marked in June. The ducts resemble a testicle in the period of the late embryogenesis. Some intensification of the differention of spermatogerous epithelium takes place in July. The endocrinocyte population between the breeding periods is more or less heteromorphic. The cytoplasm of Leydig's cells is acidophilic and contains pigmentary inclusions. Morphological and functional analyses of testes show that in June the number of androgen-producing cells lowest.