Tissue Changes in the Involuting Uterus of the Postpartum Sow

Abstract

An experiment was conducted on 42 primiparous sows of Yorkshire and Duroc breeding to determine the effects of suckling and 5 days of litter removal on the involutionary rate of the uterus. The highest rate of weight loss occurred during the first 5 days following parturition, but removal of the litters delayed the weight loss. Although involution during the first 5 days appeared to be the result of all tissue components involuting at a high rate, involution after day-6 seemed primarily to have been at the expense of the myometrium. There was a decline in the number of muscle cells with involution as well as a decrease in muscle cell size and amount of connective tissue. These atrophic changes more nearly paralleled the changes in estimated muscle weight than did changes in the cellular population. There was a greater rate of cell loss in the circular muscle layer than in the longitudinal layer, but the over-all rates of volume per nucleus change for the two layers did not differ. Copyright © 1967. American Society of Animal Science . Copyright 1967 by American Society of Animal Science