An ontogenic study of histamine and mast cells in the fetal rhesus monkey

This study was designed to determine the presence of cell-bound histamine and mast cells, if any, in the lung and skin of nonhuman primate fetuses and neonates. The results indicate that cell-bound histamine can be detected in both tissues of the rhesus monkey fetus by 60 days of gestation, the earliest age examined, at levels that are 2% to 3% of levels present in yearling animals. Levels increase markedly during the least 1 1/2 mo of gestation; however, at birth, levels are only 12% to 46% of those observed in the yearling and are lower than levels observed at 150 days of gestation. Most cell numbers in lung and skin of the fetus closely parallel histamine content.