[The potential fertility, embryonic development and hormonal status of rats selected for their estrous cycle reaction...

Illumination responsiveness (IR) is studied by selection experiments with outbred Wistar rats. Under selection is estrous cycles under permanent illumination (PI) condition, changes in hormonal status, potential fertility, and embryonic developments ats different stages are registered and compared with control. Results indicate significant changes in endocrine regulatory system in the lines exposed to PI. Functional potentiality of reproductive system gets more weak as a result of this selection, which leads to decreasing in number of ovulations, defective development of placenta, less embryo weights, higher embryo mortality. The opposite conditions are observed in rats undergone selection of stability of estrous cycle. It is concluded that the above selection reveals formation of regulatory mechanisms of reproduction on different genetical physiological bases.