THE INTRAUTERINE POSITION PHENOMENON AND PRECOPULATORY BEHAVIORS OF HOUSE MICE

The effects of intrauterine position on two sexually dimorphic. precopulatory, reproductive behaviors. were investigated in male and female mice of three different genetic strains. The two behaviors were: (I) urinary odor preference and (II) ultrasonic mating vocalizations. In addition. anogenital distance was measured both at birth and later in adulthood as a morphological index of masculinization. The intrauterine positions of individual mice relative to male and female siblings were classified according to two different classification schemes based upon hypotheses of interfetal steroid transfer: (I) the contiguity hypothesis which is based on diffusion of steroids within the uterus and (II) the transvasculature hypothesis which posits the movement of fetal steroids via the maternal vasculature. In contrast to expectations, intrauterine position defined by either the contiguity hypothesis or the transvasculature hypothesis, did not have a consistent effect on urinary odor preferences, ultrasonic mating vocalizations, or anogenital distance in male and female house mice.