Some Dietary and Hormonal Effects on Maternal, Foetal and Placental Weights in the Rat

Abstract

A negative correlation was found between the mean weight of an individual placenta and the number in a litter. Within the range examined and with the methods employed, no definite correlation between the mean weight of an individual foetus and litter size was established.Reduction of the food intake to one-half or one-third during the last 6 days of pregnancy did not result in a decrease in the number and weight of foetuses and placentae. This was apparently brought about by drawing on the maternal reserves laid down during the first 14 days of pregnancy. Absence of protein from the diet during the last 6 days resulted in a very moderate decrease in foetal and placental weights.Absence of the maternal adrenals or pituitary had no influence on foetal and placental weights. The decrease in maternal body weight after hypophysectomy was solely due to loss of appetite and could be prevented by giving the rats adequate amounts of food by stomach tube.The increase in body weight during the first 14 days of pregnancy was maintained after removal of the foetuses as long as the placentae survived. The placentae also had a favourable effect on the maternal body weight in the absence of the foetuses, when the ovaries or adrenals or the pituitary or the pituitary and ovaries were removed, but not when both ovaries and adrenals were absent. The placental factor responsible for this effect appears to act through the ovaries or adrenals.The increase in the weight of the ovaries during pregnancy was not affected by removal of the foetuses, foetuses and pituitary, or foetuses and adrenals. The adrenals of pregnant hypophysectomized rats were not heavier than those of non-pregnant hypophysectomized rats.In the preceding paper [Campbell, Innes & Kosterlitz, 1953] pregnant rats were subjected to a number of experimental procedures in an attempt to determine the factors responsible for the formation of excess ribonucleic acid in the maternal hver. In most of these experiments records were taken of maternal, foetal and placental weights. An analysis of these findings is made in the present paper. MATERIAL AND METHODSThese were the same as the ones used in the preceding paper [Campbell et al. 1953]. RESULTSBefore it was possible to analyse the effects of diet on the foetal and placental weights, it was necessary to examine whether a correlation existed between the number of foetuses in a htter and the mean weight of an individual foetus or placentae. Within the range observed, and with the methods employed, no correlation was found between the number and weights of foetuses ; the validity of this finding will be considered later. On the other hand, a significant negative correlation was found between the weights and numbers of the placentae (Fig.

Fetal and Placental Growth in the Rat following Differential Reduction of Litter Size

“…Angulo y Gonzalez (2) reported a progressive absolute increase in crown rump length difference between uterine horns as pregnancy advanced, but an analysis of the relative difference, taking account of the increase in fetal size over the last 6 days of gestation, does not yield a significant trend (p >0.05). Little evidence of a relationship was found in later studies (6,15,21). More recently an inverse relationship between fetal weight and litter size has been reported but the sample included litter sizes modified by LR in early pregnancy (3).…”

“…However, while the evidence for an inverse relationship between litter size and placental weight is unequivocal (6,9,10,15,30) that between litter size and fetal weight has been less well demonstrated. Angulo y Gonzalez (2) reported a progressive absolute increase in crown rump length difference between uterine horns as pregnancy advanced, but an analysis of the relative difference, taking account of the increase in fetal size over the last 6 days of gestation, does not yield a significant trend (p >0.05).…”

The total energy and water metabolism during pregnancy in the rat

“…There may be a true species variation in respect of water retention. Campbell, Innes & Kosterlitz (1953) indicate that the detailed patterns of weight gain and maintenance in placental pregnancy differ in rat and mouse. On the other hand, Hoffmann, Knobil & Caton (1954) have shown that there is no difference between pregnant and non-pregnant rats in their ability to eliminate an imposed water load.…”

Effects of Intermittent Glucose Infusions in Pregnant Rats on the Functional Development of the Foetal Pancreatic B-Cells

“…1-21-1-38 x 106 J/kg/day) (Campbell, Innes & Kosterlitz, 1953;Kumaresan & Turner, 1968). Nevertheless, this small additional supply of carbohydrate, given during a limited period of the day and only during the last 5 days of pregnancy, was found to be sufficient to condition the B-cells of the offspring to a premature development of the mechanism operating in glucose-stimulated insulin release.…”