A manual of histology and of histological methods / by J.M. Purser.

  • Purser, J. M.
Date:
1884
Catalogue details

Licence: Public Domain Mark

Credit: A manual of histology and of histological methods / by J.M. Purser. Source: Wellcome Collection.

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    but overlapping one another. They have no spines, and are so loosely attached to one another that the superficial cells are continually undergoing desqua- mation. The degree to which the horny transfor- mation of the cells is carried differs in different epithelia. While the general character of the compound scaly epithelium is the same wherever it is met, the thickness of the second and third layers is subject to great variety. IL Tramsitional £]pitlielmm.—This variety of stratified epithelium consists of three layers. Rest- ing on the basement membrane by their smaller ends are club-shaped cells, whose large rounded ex- tremities are directed towards the surface. Between the deeper ends of these cells, and fiUing up the interstices which here exist, are others of smaller size and very irregular shape. Covering over all, and forming the most superficial layer, are large, flattened, but thick, cells, on whose under surface are a number of deep rounded depressions, into which fit the heads of the club-shaped cells. The depressions are separated by prominent ridges, which appear as bright and curved lines, when the isolated cells are seen from their under surface. All the cells of this epithelium possess a granular protoplasm. In the two deeper layers each cell has one nucleus. In the club-shaped cells this is oval, the long axis being in the long axis of the cell. The superficial cells often contain several nuclei. The above de- scription is taken from the epithelium of the blad- der, when this viscus is contracted : when it is dis- tended all the cells are flat, and the whole epithelium is thinned, each cell having to cover a much larger area than before. In the transitional epithelium of other parts the superficial cells are much smaller than in that of the bladder. IIL I. Columnar IVon-ciliated C]pitlielmm. —The cells of this epithelium are for the most