Morphologic and cytochemical identification of microperoxisomes in human and non-human primate placental trophoblast

Summary Human and non-human primate placental villi (near term) were incubated in an alkaline 3,3 diamino benzidine (DAB) medium to identify the distribution of microperoxisomes in these tissues. Catalase-positive microperoxisomes were present in small numbers in cytotrophoblast, but were virtually absent from syncytiotrophoblast. Microperoxisomes were roughly circular in shape and about 0.2–0.3 m in diameter. They always had a close association with an element of agranular endoplasmic reticulum. The function of microperoxisomes in placenta, as in many other tissues, is uncertain. What-ever their function, they are presumably more important in cytotrophoblast metabolism than in syncytium.