Studies from a number of laboratories have suggested that a local immunological system supplies immunoglobulins to the fluids that bathe certain mucous membrane surfaces. The predominance of 5'A producing plasma cells in the lamina propria of the rectum and colon (1-5), stomach (6--8), duodenum, and jejunum (1, 8, 9) has been reported. Furthermore, 3,A-producing plasma cells have been shown to predominate in the bronchial (10-11) and nasal (7) mucosa as well as in the parotid (12) salivary gland.Immunofluorescent studies of human parofid salivary gland (12) showed that secretory "piece" was localized in acinar and ductular epithelial cells while "~A was restricted to plasma cells of the intersfifium, as well as the lumen of the glandular acini and ducts. On the basis of these results and other studies, a model was proposed for the synthesis of qcA and secretory "piece" (SP) in separate cells and a possible mechanism was suggested by which these components might combine to form the llS secretory "yA molecule (12).The present studies were undertaken to further investigate by means of immunofluorescent techniques, the cellular sites for 3'A and SP synthesis in a variety of normal human tissues. As a result of these investigations a revised model is presented involving at least in part, the intercellular (rather than intraceUular) transport of ~'A and its complexing with SP in extracellular (intercellular and luminal surface) locations. Moreover, the cellular sites of synthesis of SP and its relationship to epithelial mucins have been more clearly delineated by studies in a variety of epithelial tissues.
Material and MethodsTissue Spevimens.--Immunohistochemlcal investigations were performed on various human tissue. 14 bronchial biopsies were obtained from two locations, eight from the carina and six
Abstract. Published surveys of feline neoplasia have not specifically included biliary cystadenoma, and there is only one case report in the literature. This report is a compilation of 13 feline cases and provides a description of clinical, pathologic, immunohistochemical, and ultrastructural aspects of biliary cystadenoma as well as a discussion of comparative pathology of biliary cystadenoma in human beings and speculative histogenesis.
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