The development of microperoxisomes in the cells of the proximal tubules of the kidney and epithelium of the small intestine during the embryonic development and postnatal period.

Microperoxisomes were identified in the cells of proximal tubules of the kidney and small intestine of mice from 13-19 days old embryos, in suckling period and adult animals. Examination of both tissues after incubation in diaminobenzidine medium revealed anucleoid microperoxisomes closely related to the granular endoplasmic reticulum and occasionally found in close relation to it. The number of microperoxisomes within the cells considerably increases with the advanced stage of differentiation of both studies tissues. In the cells of proximal tubules the changes in shape and size of microperoxisomes are also observed with a higher stage of differentiation. These studies indicate that the formation and augmentation of microperoxisomes passes strictly parallelly with the differentiation, i.c. with the ability of cells to perform their specific functions.