OESTROUS SYNCHRONIZATION AND PREGNANCY BLOCKING IN WILD HOUSE MICE ( <i>MUS MUSCULUS</i> )

Abstract

Summary. In wild female house mice a skewed distribution of vaginal plugs on the days following pairing indicates an oestrous synchronization (Whitten effect) correlated with the presence of the male. Inseminated wild house mice were exposed to strange males or subjected to various types of cage changes and handling during the pre-implantation period. The strange males produced a significant reduction in pregnancy rates (Bruce effect). Changes in the physical environment produced comparable reductions in the absence of a strange male.