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We have used suspensions of isolated cells to study the metabolism of the mucosal epithelium and to compare its activity with that of other tissues in the intestinal wall of guinea pig. Only 4% of the total glycolytic activity of the intestinal wall could be attributed to the mucosal epithelium. In contrast, about 76% of the activity was located in the intestinal muscle and the remaining 20% in the intervening tissue. Clearly the view that the major proportion of the glycolytic activity of the small intestine resides in the mucosal epithelium does not apply to the guinea pig. In the light of our results, it would be prudent to re-examine any conclusions about the distribution of metabolic activity throughout the gut wall if the supporting evidence has been drawn from experiments with mucosal homogenates.

The length of the oviduct, the thickness of its wall, and the height of its mucosal epithelium and cilia were measured in (a) 0-, 2-, 4- and six-month-old rabbits, (b) rabbits ovariectomized at birth and (c) ovariectomized, estrogen-treated rabbits. The length and external diameter of the oviduct increased progressively until four months of age, after which their rates of increase declined. The thickness of the oviductal wall at the uterotubal junction was twice as large as that of the isthmus at two months of age and six times as large at four and six months of age. The height of the mucosal epithelium in the fimbriae was less than that in other oviductal segments at birth, but exceeded that in other segments at six months of age. Ciliated cells and motile cilia were absent 24 hours after birth; they were first observed two months after birth. The cilia of fimbriae were shorter than cilia elsewhere in the oviduct. Neonatal ovariectomy retarded the development of the oviduct and the mesotubarium and caused pyknosis of ciliated and non-ciliated cells of the oviductal mucosa. Cells with scarcely motile cilia were present five and one-half months after neonatal ovariectomy.

Roentgen radiation in lethal dosage, given over the abdomen of a normal dog, is followed by a physiological reaction of remarkable uniformity. The first 24 hour period following the exposure is negative clinically and anatomically, but histologically we see frank changes in the bone marrow, spleen, lymph glands, and ovaries. There are definite nuclear changes with degeneration in the crypt epithelium of the small intestine. The second 24 hour period shows slight clinical disturbances of gastrointestinal nature (vomitus and diarrhea). The mucosa of the small intestine shows scattered ecchymoses, but the histology of the small intestine is important. The necrosis of the crypt epithelium may be almost complete, while the epithelium of the villi remains practically intact. There are a little edema and invasion of wandering cells. The third 24 hour period shows increasing clinical disturbance with vomiting and bloody diarrhea. Anatomically the small intestine from the edge of the pylorus to the rim of the ileocecal valve looks raw, red, and inflamed. The crypt and villous epithelium has in large part vanished, leaving a collapsed framework of the mucosa showing a little edema and invasion of wandering cells. The 4th day marks the peak of the intoxication, and death usually takes place at this time, preceded by coma. Anatomically and histologically the picture is like that of the 3rd day. There is more evidence of mitosis and efforts of repair on the part of the intestinal epithelium. The stomach is not concerned in this reaction, but the colon may show evidences of a slight injury. The colon is obviously much more resistant than is the small intestine. We believe the evidence is conclusive that the injury done the epithelium of the small intestine is wholly responsible for the stormy clinical picture and fatal intoxication.

SUMMARY.— The mitotic activity of the uninvolved skin and buccal mucosa of patients with active psoriasis was investigated, using in vitro labelling with tritiated thymidine. The number of synthesizing DNA cells in these patients was significantly higher than in normal controls. The estimated turnover time of the normal buccal mucosa was found to be 5–8 days.

SummaryTwo anionics, a cationic and a nonionic synthetic surfactant, were examined in an in vitro phloridzinized preparation for their effects on passive intestinal permeability to glucose. These agents increased intestinal permeability to glucose in a dose-related manner with the anionic surfactant, linear alkylate sulfonate, producing this effect at lower concentrations than any of the other surfactants tested. Histologic observations demonstrated that the mucosal epithelium was not altered by low surfactant concentraions which increased intestinal permeability. Increased glucose permeability could account, in part, for decreased glucose uptake by the intestine when exposed to detergents due to the production of a “leak” at the mucosal surface preventing a glucose gradient to be established between the mucosal cell and the serosal border.

A method is described for objectively quantifying pigeon crop-sac responses to local (intradermal) prolactin injections. The procedure was used to evaluate several aspects of the crop-sac response. An apparatus was designed and constructed for holding pigeon hemicrops while applying a uniform degree of stretch on them. The device permits removal of a standardized 4 cm diameter disc of the crop-sac mucosal epithelium (ME) from the site of local injection. Responses were objectively quantified by determining the dry weight of this disc. Completeness of removal of the ME was verified by histologic inspection of intact and treated hemicrops. The dry weight of the ME was highly correlated with the thickness of the ME. The method permitted measurement of responses which were not visually detectable. Mucosal dry weight responses were highly correlated with response diameter and response area measurements. The responsiveness of the crop-sac ME to local prolactin injection was unrelated to either the initial thick...

Ultrastructural evidence is presented indicating an increase in membrane-bound ATPase activity of the mucosal epithelium of the toad urinary bladder following exposure of its serosal surface to aldosterone. Although no conclusion could be made as to whether the observed increase in ATPase activity was a direct affect of AIP, or an event secondary to an effect of AIP on other components of the cells, various possibilities are discussed in terms of current physiological information regarding the effects of aldosterone on the epithelium of the isolated toad urinary bladder.

A study was made of morphological changes occurring in the gastrointestinal tract of rats after Ce144 administration(12–15 μC/g of body weight). Destructive and necrobiotic changes in the mucosal epithelium accompanied by inflammatory reaction were characteristic of gastrointestinal tract lesions. The degree of these changes increased toward the distal end of the digestive tract, the large intestine being most affected.

Oxygen consumption rates were determined for bovine whole alveolar mucosa, alveolar mucosal connective tissue, and alveolar mucosal epithelium. The mean oxygen quotients were 0.88, 0.39, and 2.08, respectively. Because inclusion of connective tissue in epithelial slices was unavoidable, a histometric technique for estimating the connective tissue volume for correcting the raw QO2 of the epithelium was used. Of the fibers in alveolar mucosal connective tissue, 27.7% were collagenous and 72.3% were elastic. Those of attached gingiva were completely collagenous. The QO2 0.39 for alveolar mucosal connective tissue is lower than the previously reported QO2 0.69 for attached gingival connective tissue because of the additional oxygen required for hydroxylation of proline and lysine in collagen synthesis.

Iodoacetamide consistently produced chronic gastritis and ulceration, the initial effect being the production of diffuse hyperemia, focal necrosis and other abnormalities in the mucosal epithelium. With continued treatment ulceration of the body mucosa became extensive and chronic gastritis ensued. Pyloric and duodenal epithelium exhibited disturbances in proliferation kinetics. Gastric juice volume, acid and pepsin output were consistently increased in treated animals suggesting that the rate of secretion is not inhibited by iodoacetamide despite the presence of extensive ulceration but that modification of some normal control mechanisms occurs. Ulceration and gastritis is considered to arise through damage to the mucosal barrier by iodoacetamide thereby lowering the resistance of the mucosal epithelium to proteolysis; recurrent damage producing chronic gastritis.

Exposing the mucosal epithelium of the toad urinary bladder to 240 mM urea in Ringer's solution is known to cause a dramatic increase in the permeability of the zonulae occludentes and the appearance of distended, bubble-like compartments within these junctions. Examination of such osmotically disrupted junctions with the freeze-fracture technique reveals that these bubbles result from a distention of the compartments existing within the meshwork of interconnecting fibrils characteristic of the zonulae occludentes in this epithelium. Frequent discontinuities in the meshwork of fibrils are also found after osmotic disruption of the junction. These observations indicate the essential role of these fibrils in maintaining the characteristic properties of the zonula occludens as a site of cell-to-cell attachment and as a permeability seal.

Vasopressin causes dilation of the intercellular spaces of the mucosal epithelium in toad bladder, an effect previously thought to result from enhanced net transepithelial water transport. Under conditions of zero net fluid transport, vasopressin exerted the same effect in seven tissues, which indicates that the width of the intercellular spaces cannot be taken as a reliable index of net transepithelial fluid transport.

1. An in vitro preparation of the isolated everted vagina is described that allows measurements of the electrical activity across the organ. 2. The changes of the transvaginal P.D. that occur during the oestrous cycle in vivo also occur in the isolated, everted organ in vitro . 3. The transvaginal P.D. is generated by the vaginal mucosal epithelium; it is dependent on aerobic metabolism and is greatly influenced by the ovarian hormones.

Five of fourteen canine intestinal autografts frozen at −196°C for 7 days were surviving 2 wk after reimplantation. The mucosal epithelium sloughed immediately, but repopulated from surviving crypt cells over the ensuing 3–5 days. Absorptive and peristaltic functions were present at 2 wk after reimplantation.

Methods were developed for estimation of the area of the microscopic and ultramicroscopic surface of the toad bladder epithelium at various degrees of stretch. Bladder sacs fixed while containing 2.5, 5, 25 or 50 ml of mucosal fluid were studied. For a perfect, hollow elastic sphere, this range of volume corresponds to a sevenfold range of surface area. In the bladder, this increase could be achieved by unfolding of surface irregularities, with no change in surface area, or by stretching the epithelial membrane. The measured microscopic surface area increased threeinstead of sevenfold, but the ultramicroscopic surface remained constant. Thus the bladder stretches (1) by unfolding of the mucosal epithelium, and (2) by flattening of the microvilli. From measurements of the apparent thickness of the mucosal epithelium alone and of the entire bladder, we conclude that the former behaves like a flexible inelastic sheet, whereas the submucosa and serosa stretch elastically. Lateral intercellular spaces do not widen with stretch, but they do become more convoluted because of thinning of the epithelium. Thinning is unlikely to explain the increased sodium transport which follows stretching, because cytoplasmic resistance cannot approach total transepithelial resistance of this preparation.

Vasopressin increases bulk water flow across the toad bladder. To resolve whether this flow proceeds primarily between or through the surface epithelial cells, the maximum intercellular flow rate was calculated. Since the experimental flow rate is 28 times the calculated maximum, bulk water flow is likely to proceed largely through the cells of the mucosal epithelium.

Parasitic nematode worms ( Aspicularis tetraptera ) were observed microscopically in histological sections of the colons of C57BL/6StCrl female mice. These nematodes have gram-positive bacteria intimately associated with the mucosal epithelium in their alimentary tract.

A young white girl had a peculiar poikilodermatous pigmentary disturbance and a megaloblastic anemia. Both changes were resolved with vitamin B 12 therapy. Epidermal cells in areas of pigmentation were found to have abnormally large nuclei similar to those previously described in the mucosal epithelium of patients with vitamin B 12 deficiency. The epidermal nuclear size returned to normal following treatment, supporting the assumption that these enlarged nuclei were indicative of the deficiency. The data suggest that a common mechanism linked with the vitamin B 12 deficiency state may be responsible for both the pigmentary disturbance and the cytologic abnormality. The absence of cytologic changes in the skin of normally pigmented areas in this patient and in a second case of vitamin B 12 deficiency without a pigmentary disturbance is consistent with this theory.

Following approximately 40% body surface scalding, the rats were fasted for 24 hours. Compared with that of a control group, the gastric mucosa of the scalded animals contained significantly less adenosine triphosphate (ATP), and the ability of the mucosal cells to consume oxygen in vitro was also impaired. Morphological study of the early damage to the gastric mucosal epithelium in these animals as well as in other species revealed separation of the cells, often as a strip, subsequent to the development of a space at the infranuclear portion. The underlying microvessels were congested. The similarity between such metabolic and morphological changes to those observed in ischemic intestinal mucosa is discussed. It is suggested that such changes taking place in the mucosal cells, which represent the gastric barrier against the hostile intraluminal content, are an important process which may lead to the development of stress ulcer in the stomach.

White Spongy Nevus of the Mucosa. Presented byDr. Jacob Cohen(by invitation) Windsor, Ont., Canada. White man, age 28. This patient and his two older brothers have had the disease since childhood. He has received treatment with injections and local therapy in the past, being considered by various practitioners to have leukoplakia. The mucosa of the cheeks, lips, sides of the tongue, hard and soft palate, and floor of the mouth were particularly white and opalescent. The buccal mucosa was spongy in appearance, with marked thickening especially near the angles of the mouth. Slight trauma would remove much of the spongy tissue, and some patches have appeared denuded on examination. No other areas were involved. Laboratory findings .—Cultures and direct examinations demonstrated no mycotic organisms. Biopsy Report .—The sections show unusually thick mucosal epithelium with somewhat papillomatous characteristics. The living strata are covered with thick piled-up