PATHOBIOLOGY OF SALIVARY-GLANDS .4. HISTOGENETIC CONCEPTS AND CYCLINGCELLS IN HUMAN PAROTID AND SUBMANDIBULAR GLANDS CULTURED IN FLOATING COLLAGEN GELS

Localization of cells with proliferative capacity in human major saliv ary glands lacks extensive study. Minced fragments of human parotid (n = 3) and submandibular (n = 3) glands embedded in a floating collagen gel matrix and cultured for up to 28 days allowed maintenance of the three-dimensional relationship of the various cell types in these glan ds. Immunocytochemistry and electron microscopy of a time-dependent se ries of cultured gland fragments showed gradual cytologic modification of acinar cells so that acini became duct-like but also established t hat even after 28 days of culture certain cellular features allowed co ntinued identification of acinar cells. Serial section immunostaining for amylase, cytokeratins, and proliferating cell nuclear antigen (a s pecific marker for cycling cells) revealed that acinar, intercalated d uct, and excretory duct (both basal and luminal) cells are all capable of entering the cell cycle. At day 5 of culture, the number of cyclin g cells increased 16-fold in the parotid gland and 9-fold in the subma ndibular gland over that in the respective in situ gland. In this in v itro system, which perhaps simulates regenerative processes in human s alivary glands, none of the samples showed cycling cells localized onl y to segments of intercalated duct or the basal cells of excretory duc t as suggested by current histogenetic concepts.