Summary
Histology, enzyme histochemistry, and electron microscopy of the epithelium covering the rat pituitary residual lumen was studied. The anterior and posterior epithelium have similar histological and histochemical appearance, although the posterior epithelium shows stronger enzyme reactions for an esterase and many dehydrogenases. Electron microscopic studies reveal that both epithelia form a continuous lining. Anterior epithelium is in immediate contact with the interstitial spaces of the anterior lobe, while the posterior epithelium is separated from the intermediate lobe by a continuous basement lamina. The cytological features of both epithelia are also remarkably similar with scanty rough-surfaced endoplasmic reticulum, inconspicuous Golgi apparatus, round or oval mitochondria, and moderate number of lysosomal bodies. The apical surface of these cells is covered by microvilli and in some, especially posterior epithelial cells, by numerous cilia. Anterior epithelial cells and the apical portions of the posterior epithelial cells contain a number of large vacuoles with material possibly related to the colloid within the residual lumen. Electron microscopic findings suggest that both epithelia are possibly active in transfer and/or disposal of the colloid material rather than being secretory themselves. Enzyme histochemical findings support the hypothesis of an active role of these cells in metabolic processes related to phagocytosis. Based on these observations the colloid seems to be the product of the anterior lobe function.
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This study was supported in part by grants from Paulo Foundation, Helsinki, Finland (to T. V-P) and from Sigrid Jusélius Foundation (to A.U.A.) Helsinki, Finland. The authors wish to express their appreciation for the technical assistance of Mr. Mauno Lehtimäki in the electron microscopic studies. We also thank Dr. Griff T. Ross for helpful criticism in preparation of the manuscript.
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Vanha-Perttula, T., Arstila, A.U. On the epithelium of the rat pituitary residual lumen. Z. Zellforsch. 108, 487–500 (1970). https://doi.org/10.1007/BF00339655
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DOI: https://doi.org/10.1007/BF00339655