| OCR Text |
Show 172 MESSRS. SCHAFER AND WILLIAMS ON THE [Jan. 18, glands of the second region is in most parts composed of delicate connective tissue with numerous corpuscles, supporting the bloodvessels. Here and there well-defined cleft-like spaces are seen in the sections. These, no doubt, represent the lymphatics which are now known to be so numerous in the gastric mucous membrane *. They are particularly large and well marked in the neighbourhood of the pylorus (fig. 5). In some places the interglandular tissue contains a considerable number of lymphoid cells; but this is more particularly the case in the neighbourhood of the lymphoid patches, to the description of which we shall immediately come. Moreover a certain amount of lymphoid tissue may intervene between the bases of the glands and the muscularis mucosse. This last-named layer consists in most parts of two strata of muscular fibre-cells which cross one another, the inner being circular, the outer longitudinal in direction. From the more superficial or inner stratum bundles of fibre-cells pass up here and there between the glands, towards the surface; but it has not been easy to trace their ultimate destination. Probably they become eventually attached to the basement membrane. Structure of Lymphoid Patches.-These localized elevations or thickenings differ from the rest of the mucous membrane of the second region in the fact that both mucosa and submucosa are largely formed by lymphoid tissue, i. e. lymph corpuscles supported by a fine retiform tissue. This (fig. 3) extends in the mucosa towards the surface of the membrane between the glands, and is also found as a distinct stratum at their base. In the submucosa it forms a layer of some thickness immediately underneath the muscularis mucosae. The lymphoid tissue does not form a uniform layer, but is gathered at intervals into well-marked nodules or follicles (fig. 4), which cause the small rounded elevations already noticed on the surface of the lymphoid patch. Each of these elevations is, it will be remembered, marked with a small central pit (d). At the bottom of this the tubular glands fail, and the summit of the follicle is separated from the free surface merely by the layer of columnar epithelium, which itself contains numerous lymph corpuscles between the columnar cells; and these are also to be noticed free within the depression, as if they had emigrated from the subjacent lymphoid nodule. Indeed it may be doubted whether in some instances the covering of epithelium over the summit of the nodule may not be altogether absent; some of the sections obtained appear to show this ; but it is possible that it may have become accidentally detached. Below the lymphoid layer of the submucosa is the ordinary connective tissue of that tunic (s. m) supporting the larger blood-vessels, nerves, and lymphatics; and at the base of each follicular accumulation there is commonly (as shown in fig. 3) a large lymphatic sinus, into which the follicle partly dips. At other places the lymphoid tissue of the mucosa is separated from that of the submucosa by the layer of muscularis mucosae (fig. 3, m. m) ; but the latter is wanting opposite the summit of each follicle (fig. 4), and the lymphoid tissue * Loven, Nord. Med. Arkiv, 1873. |
