Regeneration-induced lengthening of the cut ends of the rat colon.

The transected colon was studied in rats in an attempt to determine whether the regenerating cut ends could be induced to lengthen by delaying or preventing their spontaneous reattachment. When the two cut ends of the defunctionalized colon were separated by a 2-3-cm length of silastic tubing mucosal, luminal and serosal continuity across the gap was restored in 8-10 weeks. Cannulation of one cut end with silastic tubing so placed as to extend 2-3 cm beyond the cut end led to lengthening of the intestine over the exposed end of the tubing by 20 weeks. The area subadjacent to regenerated mucosa filled initially with granulation tissue which was gradually replaced by loose connective tissue containing at times a thin layer of smooth muscle.

The intranodal distribution of lymph-borne particles injected intravenously.

The sequential distribution of lymph-borne, i.v. injected particles of tantalum in hepatic hilar lymph nodes was studied in rats in an attempt to determine which structural compartments of a node are responsible for mechanical filtration. The injected particles reached these nodes via liver lymph but the i.v. route of administration eliminated any possibility of disturbing either lymph flow or pressure. Particles began to enter hepatic hilar nodes only after an interval of 7-8 h. They were subsequently redistributed from marginal, trabecular and medullary sinuses to the paracortex and finally to medullary cords. Particles accumulated predominantly in the paracortex at 12-24 h and thereafter in medullary cords. This sequential pattern of distribution differed significantly from that observed previously in other lymph nodes after either intralymphatic or intratissue injection.

Transmural fluid movement in the freshly excised human gallbladder.

Direct information concerning the incidence and nature of gallbladder dysfunction in symptomatic cholethiasis was obtained by examining the rate and direction of transmural fluid movement in the freshly excised gallbladder. Each specimen was emptied of bile, cannulated and filled with a measured volume of bicarbonated Ringer's solution, suspended in the same solution at 37 degrees C., gassed with 95 per cent oxygen and 5 per cent carbon dioxide and weighed at ten minute intervals for at least one hour. Of the 42 human gallbladders examined, concentrating activity, ranging from 1 to 20 per cent of intraluminal volume per hour, was found in 14 and no activity in 17. Direction of fluid transport was found to be completely reversed in 12 additional gallbladders, four of which presented as hydrops. Histologic alterations ranged from mild to severe and could not be correlated with functional status. Application of indomethacin to the solution bathing both surfaces of 13 nonfunctioning, or partially functioning, gallbladders restored or increased function in eight. It can be concluded from this study that the concentrating activity is retained in approximately 30 per cent of patients with symptomatic cholelithiasis; cholesterol stones form in gallbladders with normal concentrating activity; the spectrum of gallbladder dysfunction ranges from simple loss of concentrating activity to hydrops, the latter reflecting complete loss of this activity plus secretion into the lumen, and dysfunction is probably induced by chemical mediators of inflammation rather than by structural changes.

Filtration of circulating particles by splenic autotransplants.

To determine whether filtration in reconstituted perifollicular marginal zones underlies particle sequestration in regenerating spleen transplants, the distribution of IV injected particles of tantalum was examined in autografts freely transplanted into subcutaneous pouches in rats. In two to six weeks old autografts removed one to three hours after particle injection, the reconstituted marginal zones contained practically all of the sequestered tantalum. At 48 hours to 20 weeks following injection, marginal zones were largely free of particles which were distributed extracellularly throughout the red pulp. This sequential pattern of distribution conformed closely to that observed in the intact spleen. The findings indicate that a reconstituted marginal zone allows splenic autotransplants to function as simple mechanical filters. Increased demand for this activity rather than for phagocytosis may be the predominant factor regulating spleen growth.

Altered erythrocyte osmotic fragility in mice with Ehrlich ascites tumor.

The osmotic fragility of erythrocytes from mice with Ehrlich ascites tumor was compared with that of erythrocytes from normal control animals. Erythrocytes collected from mice 15 days after the ip injection of tumor cells exhibited a uniform pattern of abnormal resistance to hemolysis in hypotonic saline, with 50% hemolysis occurring at an average saline concentration of 0.44% compared to an average of 0.49% for 11 controls a significant difference (P less than 0.0001). Erythrocytes from mice with this tumor apparently undergo an alteration in some component of the cell membrane that regulates either permeability to cations and water or distensibility of the cell.

Regulation of spleen growth and portal pressure in hepatic shcistosomiasis.

Growth rate and histology of splenic autotransplants in subcutaneous pockets were compared with those of autotransplants in the extrahepatic portal bed in splenectomized mice infected with cercariae of Schistosoma mansoni and in splenectomized uninfected controls. By the fifteenth week after transplantation (and tenth week after injection of cercariae) subcutaneous transplants gained 6.5 times and omental transplants 8.2 times more weight in infected animals than corresponding transplants in uninfected animals. Portal pressures averaged 11 to 13 cm of water in infected animals with transplants and 17 cm in those with intact spleens (compared to that of 6 to 7 cm in controls). Hyperplasia of white pulp with increase in germinal center activity characterized transplants as well as intact spleens of infected animals. The results suggest that a) During the first 10 weeks of experimentally induced infection, portal congestion is not the predominant mechanism regulating increased spleen growth; and b) An intact enlarged spleen appears to contribute to elevated portal pressure.