Licence: Public Domain Mark
Credit: Elements of histology / by E. Klein. Source: Wellcome Collection.
Provider: This material has been provided by Royal College of Physicians, London. The original may be consulted at Royal College of Physicians, London.
46/396 (page 26)
![branclied non-pigrneiited nucleated cells are met with ill tlui ivterstilial ur cement snLstnnce of various kinds of epitlieliuni, simple and stratified, e.r/., epidermis, epithelium of oral cavity, cornea, &c. 28. Eijitlieliid cells undergo division, and by this means a constant regeneration takes place. In those ])arts where the loss of the supeilicial layers of cells is conspicuous, such as the epidermis, the stratified epi- thelium of the tongue and oral cavity, the sebaceous follicles of hairs, the regeneration goes on more copiously than at places where no such conspicuous loss occurs—as, for instance, in the stomach and in- testines, the secreting glands, or sense organs. In the stratified pavement epithelium it is the cells of the deepest layers which chiefly divide. As a rule, this division takes place transversely in the cylindrical cells, but may also be longitudinally (A. KoUmann). The epithelial cells next to the deepe.st layer of columnar cells are to a great extent the result of the division of the latter, and as this proceeds there is a gradual shifting of the older cells towards the surface, and a simultaneous flattening of the cell pro- toplasm as well as the nucleus. 29. The interstitial substance between, and the pro- toplasm of, the epithelial cells being a soft flexible material, the cells can change their shape and arrange- ment owing to pressure exerted on them by the con- traction or distension of the subjacent membrane. Thus, the epithelium lining a middle-sized bronchus at one time appears composed of thin columnar cells in two layers ; at another, as a single layer; or again, as a single layer of short columnar cells : iii the first case the bronchus is contracted, in the second in a medium state of distension, in the third much dis- tended. Similar changes may be noticed in the epithe- lium lining the bladder and the stratuui Malpighii,](https://iiif.wellcomecollection.org/image/b24757238_0046.jp2/full/800%2C/0/default.jpg)
