Development of the hamster submandibular gland. I. The acinar-intercalated duct complex.

On the basis of light and electronmicroscopic observations of the prenatal and postnatal development of the hamster submandibular gland, several stages of cyto-morphodifferentiation were identified. The initial critical period was between the 13th and 14th day of gestation. An anlage of 'undifferentiated' pluripotential stem cells was transformed into terminal tubules which consisted of secretory cells, myoepithelial cell precursors and stem cells. From the periphery of the terminal tubules originated terminal buds which were the forerunners of the acini. The intercalated ducts, terminal tubules and terminal buds constituted the 'terminal tubule complex'. Several morphological similarities were noted between the hamster and the rat developing SMG and between the hamster developing SMG and the rat parotid. It seemed that various human salivary gland tumors recapitulated different stages of their normal cytomorphogenesis.