The effects of multiple pregnancies and age on the elastic tissue of uterine arteries in the guinea pig

Abstract

Abstract Mesometrial arteries and representative areas of the uterus were obtained from young and old postpartum guinea pigs. The tissues were fixed in Bouin's solution and then stained with Taenzer's Orcein and Verhoeff's elastic stains. Picro‐indigo‐carmine and Van Gieson were used as counterstains. It was found that the distribution of elastic tissue and the number of elastic and muscle layers in the arterial walls in general reflected the number of pregnancies the animal had had. This was found to be reliable only up to three pregnancies, after which the animals could be referred to only as being multiparous. There appeared to be a continuous increase in the amount of elastin in the blood vessels with each successive pregnancy. Further, aged animals showed more elastin in their vessels than younger ones of comparable parity. The formation of the new internal elastic membrane appeared to be delayed in older females. Our observations suggest that there might be a decrease in the postpartum resorption of elastin as a result of successive pregnancies and aging. They also suggest that the delay in the formation of the new internal elastic membrane in older postpartum females is probably due to aging.