Enzyme histochemistry in fetal human hearts and kidneys during intrauterine development. Qualitative and quantitative...

The activities of three enzymes, glycerol-3-phosphate dehydrogenase, succinate dehydrogenase and dipeptidylpeptidase IV, were histochemically demonstrated and cytophotometrically measured in fetal human hearts and kidneys. During the intrauterine development from the 7th to the 19th week 29 fetuses in 6 stages of age were investigated. Positive enzyme reaction was found in the myocardium of left and right ventricle and septum and in the different parts of the nephron. During the investigated period of development the enzyme activities changed in both heart and kidney. At the 16th week the activities of glycerol-3-phosphate dehydrogenase and succinate dehydrogenase showed the maximum in the heart, in contrast to kidney, where at this stage activity minima of succinate dehydrogenase and dipeptidylpeptidase IV were measured. The myocardium of the right ventricle showed higher metabolic activity than the right one, which could reflect the higher load of the right ventricle in the fetal circulation. Within the nephron differences of enzyme activities were observed. The highest enzyme activities were always measured in the proximal tubules, interpreted as sign of high degree of differentiation.