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Home , Mucous membrane, Muscular layer

135

ANATOMICAL NOTES

THE AMOUNT OF' MUCOSAL TISSUE IN THE By C. P. MARTIN AND J. BANKS Department of Anautomy, McGill University, Montreal, Canada SOME time ago our colleague, Prof. B. P. Babkin, of the Department of Physiology, McGill University, asked if we could furnish him with exact information as to the amount of mucosa or secretary tissue in the small intestine. A search of the recognized text-books and literature failed to supply the required information, although, as pointed out by Dr Babkin, it was available in part in the case of the dog. Abel & Kubota (1919) stated that in a dog weighing 2014 kg. they removed, opened, washed and dried between sheets of filter paper the entire and small in- testine, and then scraped off the mucosa with sharp pieces of glass: they found that the scrapings weighed 242 g., while the residual muscular part of the alimentary tract weighed 335 g. Apart from this paper we could find no reference to the weight of the of the small intestine. Accordingly, through the kind co-operation of the Department of Pathology of McGill University, we obtained the entire small intestine of six adult men who had died from causes that had no connexion with the alimentary canal. The mesenteries and all fat were carefully dissected off these specimens and they were then opened and thoroughly washed out. To preserve them, they were placed in a solution of 5 00 formalin with a little glycerine and some alcohol. The , and were separated, each was pinned down on a cork mat and the entire mucous membrane was dissected away from the muscular layers a tedious but quite feasible operation which left both the mucous membrane and muscular layers as continuous sheets. The sheet of mucous membrane still retained its , although, unlike the , it stretched considerably as it was detached. Both sheets were then pressed firmly by hand between thick sheets of blotting paper and weighed. The results are set out in Table 1. It is difficult to decide exactly how much drying by pressure should be carried out; the mucosa especially can contain a considerable quantity of fluid, and how much of this should be regarded as a normal constituent of the tissue was uncertain. Accordingly, we weighed the last two specimens again after subjecting them to heavier and more prolonged pressure. They were laid out in a single layer between dry towels and placed in a letter-press, where for 10 min. they were tightly squeezed. They were then placed between thick sheets of blotting paper and again squeezed in the press for a further 10 min. The results of these second weighings are shown at the foot of the table, but we think that these weights should be disregarded as they were obtained after subjection of the tissues to a much severer drying process than is usually adopted in estimating the weight of viscera. In one specimen the complete pancreas was also present and as a standard of comparison we give its weight after gentle drying with a cloth. In only one specimen (no. 5) did we find any recognizable pathological lesion, but we consider that no. 6, in which the weight of the mucous membrane in the jejunum and ileum was far in excess of that found in the five other examples, should be regarded as abnormal and possibly pathological. In this specimen the mucous membrane was extraordinarily thick and yellowish in appearance, but the mesenteries and outside of the intestine contained little fat. Our results show that the weight of the entire small intestine and that of its mucosa vary over a wide range. The weight of the mucous membrane, excluding 136 Anatomical notes specimen 6, varies from 72-46 to 243-9 g., the average being 166-35 g. In the duo denu.m and jejunum the mucous membrane makes up almost two-thirds of the tota weight of the intestine, whereas at the lower end of the ileum it barely makes up one-third. The weight of the mucosal tissue in the small intestine is therefore con- siderable and appears to be appreciably in excess of the total weight of the pancreas. Of course, the mucous membrane, as dissected off by us, contains much more than pure secretary tissue-blood vessels, lacteals and the muscularis mucosa are all included-but the pancreas and the salivary glands, as usually weighed, likewise contain considerable amounts of vascular and supporting fibrous tissue.

Table 1. Weight (in grams) of the mucosa of the small intestine in six adult male human subjects Relative weight of mucosa to muscle (weight of muscle in each case being taken as 1.0) Total weight of mucosa in Total weight Total weight of r A Total of small Duo-. Je- Duo- Je- small intestine Muscle Mucosa denum junum Ileum denum junum Ileum intestine Hand dried (1) 270-50 115-50 157-00 19-00 107-00 31-00 1-77 1-72 0-74 1-34 (2) 413-20 169-30 243-90 29-60* 125-00 89-30 2-00 1-18 1-12 1-33 (3) 250-43 93-85 129-25 21-32 76-51 31-42 2-00 1-58 0-90 1-36 (4) 135-41 62-95 72-46 12-53 40-80 19-13 2-17 1-60 0-60 1-15 (5)t 459-94 230-80 229-14 35-00 166-74 27-40 1-33 1-08 0-55 1-00 (6)t 474-07 129-94 344-13 25-74 217-73 100-66 1-90 3-88 1-67 2-64 Dried by press (5)t 373-84 194-10 179-74 35-00 121-74 23-00 1-33 1-00 0-50 0-81 (6)1 340-25 82-59 221-66 16-40 133-66 71-60 1-80 3-66 1-90 2*56 * This figure is doubtful, as the material became accidentally over-dried and had to be remoistened. t Two small ulcers were found at the upper end of the duodenum in this specimen and the blood vessels in the vicinity were thrombosed. In this specimen the total weight of the pancreas, after gentle hand-drying, was 62-13 (the pancreas was not available in the other cases).

REFERENCE ABEi, J. J. & KUBOTA, S. (1919). J. Pharmacol. 13, 243.