Lectures on the anatomy and physiology of the intestinal canal : more especially of its mucous membrane : being the Croonian Lectures for 1842, delivered at the College of Physicians / by R. B. Todd.

  • Todd, Robert Bentley, 1809-1860.
Date:
1842
Catalogue details

Licence: Public Domain Mark

Credit: Lectures on the anatomy and physiology of the intestinal canal : more especially of its mucous membrane : being the Croonian Lectures for 1842, delivered at the College of Physicians / by R. B. Todd. 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.

    10/24 (page 10)
    their views were based on the indications of a coarse anatomy, and since, from their not having availed themselves of the microscope, they were unable to obtain a minute ana- tomical analysis, they failed in demonstrating, what they had so happily surmised. In the description I am now about to give, I have great pleasure in acknowledg- ing the assistance I have derived from the researches of my valued friend, Mr. Bowman, whose excellent investigation of the minute anatomy of voluntary muscles is now well known to anatomists*. In the present ac- count, however, I shall chiefly follow my own observations. I have said that mucous membrane lines the interior of the body, and that it per- meates the ramifications of the elementary tubes of which the glands are composed. It, indeed, forms the walls of those tubes, and to analyse its structure, we cannot do better than examine one of them with high powers in the microscope. The kidney affords a favourable opportunity for this purpose, and in its tubuli uriniferi, we shall find the elementary constituents of mucous membrane. Let me here remark, that all examinations of this kind ought to be made on parts quite in the fresh state, for the cohesion of the minute elements of this texture disappears very soon after their vitality f. It had been ascertained by Henle, that the wall of a uriniferous tube is composed of two elements—a transparent membrane, and an epithelial covering; and to Mr. Bowman is due the merit of having shown, that these elementary parts exist, wherever true mucous membrane is found, and that skin is similarly compounded. The primary, and most essential of these elements is the transparent membrane. It affords, perhaps, the simplest and most beautiful example of a membranous ex- pansion which can be met with in the body. It forms the basis, on which the epithelial element is deposited ; and to it the mucous membrane owes whatever cohesive power, strength, or other physical property, it pos- sesses. Hence Mr. Bowman has given it the appropriate name of basement mem- brane ; and by this name I shall designate it in the remainder of these lectures. The basement membrane is homogeneous, per- * Since this lecture was delivered, Mr. Bow- man has published an able article, on Mucous Membrane, in the Cyclopaedia of Anatomy and Physiology, Part XXIII.; to which the reader may refer for details beyond the scope of this lecture. f The structure of mucous membrane has recently been described by a distinguished ana- tomist, from preparations made by prolonged maceration ! I have no doubt that, if M. Flou- rens would examine, with the microscope, the layers which he has so skilfully dissected, he would find that they are composed of areolar tissue. fectly transparent; the highest powers of the microscope cannot detect in it any definite arrangement of particles. The Ger- mans would call it structureless {struldurlos). We are not without examples of the occur- rence of a similar texture elsewhere in the body. The transparent tube, that envelops the fleshy elements of the primitive fasci- culus of voluntary muscle, presents precisely the same characters. The wall of the nerve tubule, which contains the soft neurine, is equally transparent and structureless: so, also, are the posterior layer of the cornea (membrana Demoursii of the French), and the capsule of the crystalline lens. The basement membrane does not admit vessels into its texture. These ramify on its deep or parenchymal surface, and are supported by the submucous cellular tissue, very distinct in the intestinal canal, or, as in certain glands, by a soft cytoblastema, which seems to be derived from recently effused liguor sanguinis, and from which probably the basement membrane and the epithelium derive their nutrition and growth. Fig. 1. Human Kidney Tubule, magnified 300 diameters. c, basement membrane, from which the epithe- lium has been detached. The basement membrane may be readily seen in other parts besides the kidney tubes. In the tubuli seminiferi of the testicle it is highly developed, and of considerable thick- ness (fig. 2). In the glands whose tubes present vesicular terminations, it is also highly developed, as in the pancreas or sali- vary glands (fig. 3). In the Meibomian glands, it may be very distinctly seen; also in the tubes of the stomach, especially towards their deep, or adherent extremity*. * I am satisfied that Wasmann is incorrect in describing the dark part of the mucous mem-