Developmental distribution of microperoxisomes in the rat submandibular gland.

The present study investigated the size, number, and distribution of microperoxisomes (MP) during the prenatal and postnatal development of the rat submandibular gland (SMG). A three-fold increase in MP number per cell was observed in the cells of the rudiment from the 15th to the 16th day of gestation. The early secretory and striated duct cells contained about 9.0 MP. The number of MP per secretory cell decreased such that 3.5 MP were found in each mature acinar cell. In the striated duct cells, MP number progressively increased to 40.0. As the convoluted granular tubule cells (CGT) developed from striated duct cells there was an increase in MP number from 16.0 to 26.0/cell. At maturity, the convoluted granular tubule cells contained only 14.0 MP. Throughout development of the SMG, intercalated duct cells showed only rare MP. The data suggests that the number, size, and distribution of MP changes as a function of the particular path of differentiation followed by the various cells in the rat SMG.