To evaluate interrelationships among epithelial cells, and between morphology and function in the microenvironment, we studied the ultrastructural morphology of epithelial cells in sections of human thymus from donors aged 2 months to 31 years. Six types of epithelial cells were observed: “subcapsular-perivascular” (type 1); “pale” (type 2); “intermediate” (type 3); “dark” (type 4); “undifferentiated” (type 5); and “large-medullary” (type 6). Cells of types 2, 3 and 4 were found throughout the organ. The type-2 to -4 epithelial cells may represent various stages in a differentiation process. In this, type-2 cells are very active and type-4 cells are possibly degenerating elements. Type-4 cells can also contribute to Hassall's corpuscles. Type-5 cells were located mainly in the cortico-medullary region and showed the morphological characteristics of undifferentiated elements. Type-6 cells were located exclusively in the medulla and displayed characteristics of cellular activity. Small Hassall's corpuscles consisted of type-6 epithelial cells; in larger corpuscles many nuclei of type-6 cells were found. Cells of types 2 and 6 contained tubular structures (diameter approximately 20 nm).
Concerning the function of thymus epithelial cells, the features associated with protein synthesis observed in cellular types 2 and 6 make them likely candidates for humoral factor-producing and/or secreting elements. In addition, type-2 and -3 cells in the cortex appear to contribute to a special pattern of epithelium-lymphocyte interaction (“thymic nurse cells”), as demonstrated by the intracytoplasmic location of lymphocytes in the epithelial cells. The various steps in intrathymic T-cell maturation occur at locations in a microenvironment composed of morphologically distinct epithelial cells.
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Abe K, Ito T (1974) Tubular complex of small lymphocytes in lymphatic tissue of the mouse. Arch Histol Jpn 37:133–142.
Arya S, Gilbert EF, Hong R, Bloodworth JMB Jr (1982) The thymus. In: Bloodworth JMB Jr (ed) Endocrine pathology. Williams and Wilkins, Baltimore, chapter 19.
Bearman RM, Levine GD, Bensch KG (1978) The ultrastructure of the normal human thymus: a study of 36 cases. Anat Rec 190:755–781.
Clark SJ Jr (1963) The thymus in mice of strain 129/J, studied with the electron microscope. Am J Anat 112:1–33.
Duijvestijn AM, Hoefsmit EC (1981) Ultrastructure of the rat thymus: the micro-environment of T-lymphocyte maturation. Cell Tissue Res 218:279–292.
Frazier JA (1973) Ultrastructure of the chick thymus. Z Zellforsch Mikrosk Anat 135:191–205.
Gaudecker B von (1978) Ultrastructure of the age-involuted adult human thymus. Cell Tissue Res 186:507–525.
Gaudecker B von, Müller-Hermelink HK (1980) Ontogeny and organization of the stationary non-lymphoid cells in the human thymus. Cell Tissue Res 207:287–306.
Gelfand EW, Dosch H-M, Shore A, Limatibul S, Lee JWW (1980) The role of the thymus in human T-cell differentiation. In: Gelfand EW, Dosch H-M (eds) The biological basis for immunodeficiency disease. Raven Press, New York, pp 39–56.
Gorgollon P, Ottone-Anaya M (1978) Fine structure of canine thymus. Acta Anat 100:136–152.
Haar JL (1974) Light and electron microscopy of the human fetal thymus. Anat Rec 179:463–476.
Haelst U van (1967) Light and electron microscopic study of the normal and pathological thymus of the rat. I. The normal thymus. Z Zellforsch 77:534–553.
Hay ED, Revel JP (1963) Autoradiographic studies of the origin of the basement lamella in Ambystoma. Dev Biol 7:152–168.
Haynes BF, Shimizu K, Eisenbarth G (1983) Identification of human and rodent thymic epithelium using tetanus toxin and monoclonal antibody A2B5. J Clin Invest 71:9–14.
Hirokawa K (1969) Electron microscopic observation of the human thymus of the fetus and the newborn. Acta Pathol Jpn 19:1–13.
Hirokawa K, McClure JE, Goldstein AL (1982) Age-related changes in localization of thymosin in the human thymus. Thymus 4:19–29.
Hoshino T (1963) Electron microscopic studies of the epithelial reticular cells of the mouse thymus. Z Zellforsch 59:513–529.
Hwang WS, Ho TY, Luk SC, Simon GT (1974) Ultrastructure of the rat thymus. A transmission, scanning electron microscope, and morphometric study. Lab Invest 31:473–487.
Ito T, Hoshino T (1966) Fine structure of the epithelial reticular cells of the medulla of the thymus in the golden hamster. Z Zellforsch 69:311–318.
Janossy G, Bofill M, Trejdosiewicz LK, Chilosi M (1983) Cellular differentiation of lymphoid subpopulations and their microenvironments in the human thymus. In: Müller-Hermelink HK (ed) The thymus: histophysiology and pathology. Springer, Berlin, in press.
Järplid B (1974) Dark reticular cells in the thymus of mice. Acta Radiol 13:319–328.
Kameya T, Watanabe Y (1965) Electron microscopic observations on human thymus and thymoma. Acta Pathol Jpn 15:223–246.
Kater L (1973) A note on Hassall's corpuscles. Contemp Top Immunobiol 2:101–109.
Kater L, Oosterom R, McClure J, Goldstein AL (1979) Presence of thymosin-like factors in human thymic epithelium conditioned medium. Int J Immunopharmaco 1:273–284.
Kendall MD (1980) Avian thymus glands: a review. Dev Comp Immunol 4:191–209.
Kendall MD, Blackett NM (1983) Ultrastructural studies on the thymus gland after administration of phenylhydrazine to bank voles (Clethrionomys glareolus). Cell Tissue Res 232:201–219.
Le Douarin NM, Jotereau FV (1981) The ontogeny of the thymus. In: Kendall MD (ed) the thymus gland. Academic Press, London, pp 37–62.
Mandel T (1968) Ultrastructure of epithelial cells in the cortex of guinea pig thymus. Z Zellforsch 92:159–168.
Pereira G, Clermont Y (1971) Distribution of cell web-containing epithelial reticular cells in the rat thymus. Anat Rec 169:613–626.
Reynolds ES (1963) The use of lead citrate at high pH as an electron-opaque stain in electron microscopy. J Cell Biol 17:208–212.
Richardson KC, Jarrett L, Finke EH (1960) Embedding in epoxy resins for ultrathin sectioning in electron microscopy. Stain Technol 35:313–323.
Ritter MA, Sauvage CA, Cotmore SF (1981) The human thymus micro-environment: in vitro identification of the thymic nurse cells and other antigenetically-distinct subpopulations of epithelial cells. Immunology 44:439–446.
Sato T, Shamoto M (1973) A simple rapid polychrome stain for epoxy embedded tissue. Stain Technol 48:223–227.
Savino W, Santa-Rosa GL (1982) Histophysiology of thymic epithelial reticular cells. Arch Histol Jpn 45:139–144.
Schmitt D, Monier JC, Dardenne M, Pleau JM, Bach JF (1982) Location of FTS (facteur thymique sérique) in the thymus of normal and auto-immune mice. Thymus 4:221–231.
Shier KJ (1981) The thymus according to Schambacher: medullary ducts and reticular epithelium of thymus and thymomas. Cancer 48:1183–1199.
Singh J (1981) The ultrastructure of epithelial reticular cells. In: Kendall MD (ed) The thymus gland. Academic Press, London, pp 133–150.
Wijngaert FP van de, Rademakers LHPM, Schuurman H-J, De Weger RA, Kater L (1983) Identification and in situ localization of the thymic nurse cell in man. J Immunol 130:2348–2351.
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van de Wijngaert, F.P., Kendall, M.D., Schuurman, H. et al. Heterogeneity of epithelial cells in the human thymus. Cell Tissue Res. 237, 227–237 (1984). https://doi.org/10.1007/BF00217140
- Epithelial cells