The Choledochoduodenal Junction in Sheep and Goat
The choledochoduodenal junction was studied in 15 sheep, 5 goats and 7 sheep fetuses by maceration technique, microdissection, and by microscopic examination. The bile duct extended from the junction of the hepatic and cystic ducts, entered the duodenum at the beginning of its descending part on the dorsomedial aspect, ran distally in the wall for about 1.5 cm and ended with an opening facing distally without raising a papilla. The average length of the bile duct was 8 cm; its structure along its course was also described.
The musculature of the gall bladder and biliary pathways in the guinea-pig.
A study of the gall bladder and the biliary pathways was carried out in the guinea-pig by light and electron microscopy. The musculature of the distended gall bladder measures only about 220 microns in thickness and consists of muscle bundles running in various directions. The muscle cells are loosely packed and are much smaller than the muscle cells of the intestinal muscularis externa. They resemble, in structure and arrangement, the cells of the muscularis mucosae of the intestine. In the cystic duct, the hepatic duct and the upper third of the bile duct, the musculature is similar to that of the gall bladder but is sparser and mixed with abundant connective tissue (fibromuscular layer). In the middle and lower portions of the bile duct there is a progressive increase in the amount of musculature. While the outer diameter of the organ remains constant (about 1.3 mm), the amount of muscle in a transverse section of the duct increases more than ten times along the length of the duct. Here the muscle cells are large and densely packed and closely resemble those of the duodenal muscularis externa. The bile duct forms with the duodenum an angle of about 30 degrees and it opens into a large cavity within the duodenal wall, the ampulla, which has a complex muscular system of its own. The ampulla is drained into the duodenal lumen through a duct within the papilla, around which lies a ring of circular musculature. The pancreatic duct opens independently into the duodenum about 6 cm aboral to the bile duct.
FINE STRUCTURE OF THE LAMINA MUSCULARIS MUCOSAE.
Phase contrast and electron microscopic studies of the lamina muscularis mucosae of the mouse intestine were carried out in order to elucidate the cytologic detail of the cells and their orientation. This smooth muscle element was found to be a three-dimensional network of flattened cells with elongate processes, the processes of each cell contacting those of its neighbors. The lower limit of the net is a more densely packed layer of nonpolarized flattened cells underlying the bases of the glands of Lieberkuhn. These tubular intestinal glands are enmeshed in the net of muscle cells. It is suggested that the muscularis mucosae serves a secretion-moving function, expressing the products of the intestinal glands.