Effects of the high growth (HG) mutation on reproduction in high growth (HG) female mice

Reproductive performance was characterized in females of a line of mice hom ozygous for a recessive mutation with a major effect on growth, the high gr owth (hg) mutation. Specifically, the age at onset of puberty, length of th e estrous cycle, ovulation rate, and gestation length in high growth (HG) m ice were determined and compared with control mice. HG females reached pube rty at an age similar to control animals, exhibited normal ovulation rates and estrous cycle length, but had a shorter length of estrus. Number of fet uses at Day 17 of gestation was greater and gestation length was longer in HG females. The HG females exhibited a variety of reproductive disorders, i ncluding increased incidence of repeated detection of mating plugs without intervening pregnancy ("replug"), in creased incidence of repeated detectio n of mating plugs within an interval of 1-8 days without intervening pregna ncy ("recycle"), increased interval between pairing with a male and detecti on of the first mating plug, increased interval between mating and concepti on, increased postnatal mortality, decreased litter size, and increased inc idence of vaginal septum.