LACTOSE CONTENT OF MAMMARY GLANDS OF PREGNANT RATS NEAR TERM: EFFECT OF REMOVAL OF OVARY, PLACENTA AND FOETUS

Publisher Website
Google Scholar
Abstract
SUMMARY: The time of initiation of copious milk secretion in the mammary glands of pregnant rats and the effects of removal of ovaries and/or placentae with foetuses on lactogenesis were investigated by measuring the lactose content of the mammary glands. In the normal pregnant rat, lactose was detected in the mammary gland on the 20th day of pregnancy, but not on the 15th. An abrupt increase in lactose content occurred on the 21st day of pregnancy. Bilateral or unilateral ovariectomy, and Caesarean section, with or without ovariectomy, performed on the 18th or 19th day of pregnancy all resulted in a marked increase in the lactose content on the 2nd day after operation. Bilateral ovariectomy caused early delivery of the young and lactose content in the gland increased further after delivery. Foetuses in the unilaterally ovariectomized rats were retained normally to term. Possible participation of placentae and foetuses in the mechanism of lactogenesis in pregnant animals by controlling the activity of the ovary is discussed.