Intracellular production of adrenal renin in the fetal mouse. An immuno-electron microscopical study

Renin-containing cells in fetal adrenal glands of the mouse were investigated with the protein A-gold immunocytochemical technique. On Day 14 of gestation, a small number of specific granules were weakly immunoreactive and were distributed in the Golgi region. Sometimes, apparent exocytosis of gold-labelled particles could be seen opening into the extracellular space. On Day 16 of gestation, numerous gold particles were demonstrated in the Golgi region as well as in the specific secretory granules. Immunoreactivity of the specific granules was increased as compared with Day 14, though some granules were observed to have no reaction with the antibody. On Day 18 of gestation reactivity for renin decreased, while a few clustered immunoreactive granules were demonstrated just beneath the cell membrane. No gold particles were observed in the Golgi apparatus during this period and more granules negative for renin were noted than on Day 16 of gestation. These results suggest that renin is produced and released temporarily by adrenal cortical cells in the late fetal life of the mouse.