RHYTHMIC CHANGES IN THE FETAL LIVER AFTER FEEDING

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Abstract
As far as the maternal liver is concerned, this study confirms (a) the existence of a cyclic activity in the deposition of some of the better-known hepatic constituents, and (b) the work of Goodwin and Higgins in that there appears to be an increased rapidity of metabolism of these constituents in the liver during pregnancy. The authors were unable to measure the actual increase in the amts. of these constituents formed in the fetal liver, yet by means of % detns. they were able to show that the proportion of glycogen in fetal livers increased and then decreased following feeding of the mother. The curve representing the changes in the % of glycogen, points of which were plotted at intervals of 2 hrs. throughout the period of 22 hrs. following feeding, shows a gradual increase from the proportions present at 9 a.m. to an amt. ca. twice as high at 9 p.m. Thereafter, with some fluctuations, the trend of the curve is downward, and at 9 the following morning a mean 5% of glycogen was again encountered. Aron showed that the development of physiologic potency in the fetal liver, as far as glycogen is concerned, is correlated with the appearance of islets in the pancreas. Early in development, the placenta serves to regulate fetal metabolism of glycogen; however, with the growth of the islets of Langerhans, this function is gradually transferred to the liver and the placental glycogen steadily decreases in amt. until term. Fetal hepatic glycogen in proportion to the wt. of the liver was higher than maternal liver glycogen, both before and after feeding. During a 24 hr. fast, maternal hepatic glycogen was reduced to an amt. constituting but 0.29% of the total hepatic wt., whereas much higher values were maintained in the fetus. After food had been withheld for 24 hrs., when the % of glycogen in the maternal liver had dropped to 0.29, a mean % of glycogen in the fetal liver of 4.95 was recorded. Immediately on feeding, when glucose appeared in the maternal blood stream, %s of glycogen at once began to rise in the fetal liver. Glucose probably passed the placental barrier and served to increase the already large store of glycogen present in the fetal liver. Whereas hepatic glycogen increased in the maternal liver during the period after feeding, from 0.29% of the hepatic wt. to 3.1%, the % increase in the fetal liver was 4.95-10.60. The curve of these % changes is not particularly bimodal in character, but neither is that depicting the total changes of glycogen in the maternal liver. The peak in the amt. of glycogen stored in the maternal liver was reached at 5 p.m., whereas the high point on the curve for % of fetal hepatic glycogen did not occur until 9 p.m. Percentage changes are not comparable to actual changes in wt., and yet because of the similarity in wts. of the fetuses and of the fetal livers the authors are inclined to believe that were they able to record total changes in fetal hepatic glycogen during the cycle, a somewhat comparable curve would result.

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