FURTHER STUDIES ON PRENATAL FUNCTIONAL RELATIONS BETWEEN RAT PINEAL GLAND AND EPITHELIUM OF LOWER ILEUM

ABSTRACT It has previously been demonstrated by the author that the developing pineal gland of the rat possesses functional activity during a definite period. Destruction of the active gland in utero regularly causes marked changes in the lower ileum, the epithelial cells being filled with large eosinophilic inclusions of carbohydrate-protein nature. These inclusions are a manifestation of the absorption of muco- or glycoproteins from the amniotic fluid, known to be ingested by the foetus. In the present study, pinealectomy in utero was performed by electrocoagulation on forty-eight foetuses at certain specific stages. Twenty-six foetuses were sham-operated. For comparison, seventy-two unoperated controls were analyzed. The stage at which the inclusions first appear after pinealectomy is determined and discussed. Furthermore, the foetuses have been analyzed near the expected term after pinealectomy at different stages. Destruction of the gland before pineal secretory activity causes very marked changes in the ileal epithelium; these are less distinct when the operation is performed during the secretory period. Pinealectomy after the secretory period does not cause any changes in the lower ileum in comparison with sham-operated control foetuses. Thus, a remote action has been demonstrated for the foetal pineal gland. The function seems to be that of preventing significant intestinal absorption of intact proteins while the foetus is still within the uterus. After birth such absorption is known to occur normally from colostrum. The possible connection of the foetal adrenals to the prenatal pineal function is discussed.