Abstract
Epithelia noted for their water transport have been studied by electron microscopy with particular emphasis upon basal specializations. Epithelia of the submaxillary gland, choroid plexus, and ciliary body are described in this article, and compared with previous observations on the kidney. The basal surface of all these epithelia is tremendously expanded by folds which penetrate deeply into the cytoplasm. In the submaxillary gland this is particularly notable in cells of the serous alveoli and in the secretory ducts. In these instances the folds have a fairly regular distribution and have a marked tendency to turn back upon themselves and so form repeating S-shaped patterns. In the choroid plexus the penetrating basal folds are limited to the lateral regions of each ependymal cell where they blend with the intercellular membranes that are also folded. In the epithelium of the ciliary body it is the inner layer that is specialized. The surface adjacent to the cavity of the eye penetrates irregularly, nearly through the full depth of the cell layer. The exposed surface is, in a fundamental sense, the basal surface of this epithelial layer. It is apparent that the pattern of folding is quite distinctive in the different epithelia. Therefore, the specializations should be regarded as analogous rather than homologous. Topographic considerations presumably limit the manner in which basal cell surfaces might be expanded. Penetrating folds would seem to represent almost the only possible solution.
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Selected References
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- DEMPSEY E. W., WISLOCKI G. B. An electron microscopic study of the blood-brain barrier in the rat, employing silver nitrate as a vital stain. J Biophys Biochem Cytol. 1955 May 25;1(3):245–256. doi: 10.1083/jcb.1.3.245. [DOI] [PMC free article] [PubMed] [Google Scholar]
- MAXWELL D. S., PEASE D. C. The electron microscopy of the choroid plexus. J Biophys Biochem Cytol. 1956 Jul 25;2(4):467–474. doi: 10.1083/jcb.2.4.467. [DOI] [PMC free article] [PubMed] [Google Scholar]
- PALADE G. E. A study of fixation for electron microscopy. J Exp Med. 1952 Mar;95(3):285–298. doi: 10.1084/jem.95.3.285. [DOI] [PMC free article] [PubMed] [Google Scholar]
- PEASE D. C. Electron microscopy of the tubular cells of the kidney cortex. Anat Rec. 1955 Apr;121(4):723–743. doi: 10.1002/ar.1091210403. [DOI] [PubMed] [Google Scholar]
- PEASE D. C. Electron microscopy of the vascular bed of the kidney cortex. Anat Rec. 1955 Apr;121(4):701–721. doi: 10.1002/ar.1091210402. [DOI] [PubMed] [Google Scholar]
- VAN BREEMEN V. L., CLEMENTE C. D. Silver deposition in the central nervous system and the hematoencephalic barrier studied with the electron microscope. J Biophys Biochem Cytol. 1955 Mar;1(2):161–166. doi: 10.1083/jcb.1.2.161. [DOI] [PMC free article] [PubMed] [Google Scholar]
- WISLOCKI G. B., LADMAN A. J. The demonstration of a blood-ocular barrier in the albino rat by means of the intravitam deposition of silver. J Biophys Biochem Cytol. 1955 Nov 25;1(6):501–510. doi: 10.1083/jcb.1.6.501. [DOI] [PMC free article] [PubMed] [Google Scholar]