Cytology of oocytes in ground squirrels (Citellus citellus L.)

Oocytes of primordial, primary, growing, and Graaf follicles of the ovaries of 96 ground squirrels (Citellus citellus L.) were studied during the four seasons of the year. Multilamellar bodies in the oocytes were observed by electron microscopy. The bodies underwent changes during the follicle growth. The vesicles included in the multilamellar bodies were filled with an amorphous substance, while in Graaf follicles trapezoidal, rhomboidal, and hexagonal inclusions were found. The primordial follicle of the oocyte had no Balbiani body. In the hibernating ground squirrel the functions of the Balbiani body were probably performed by the multilamellar bodies, which were considered to be analogous to the Balbiani body.