FREQUENT FAILURE OF A SINGLE INSEMINATION TO ACTIVATE THE CORPORA LUTEA OF THE RAT SUFFICIENTLY FOR IMPLANTATION OF FERTILIZED OVA

Abstract

Previous expts. with vasec-tomized [male] rats showed that single-insemination matings failed to produce pseudopregnancy in 1/3 of the cases, presumably because of insufficient stimulation of the pituitary. The present expts. were designed to find out whether, in the presence of healthy fertilized eggs resulting from single-insemination matings with fertile [male][male], implantation could occur in such inadequately stimulated [female][female]. The theoretically probable results were obtained: approximately one-third of 109 single-insemination matings were followed by 4- to 5-day cycles although the eggs were fertilized and developing normally at the time of the new estrus. The other 2/3, with only 4 exceptions, resulted in normal litters. Three-plug matings always resulted in pregnancy or pseudopregnancy even in cases where the 2d and 3d plugs were made by vasectomized [male][male].