Enzyme Histochemical Investigations of the Mesonephric Nephron

Abstract

For the further subdivision of nephron segments, the histochemical demonstration of the activity of the oxidoreductases succinic dehydrogenase (SDH), and NAD- and NADP-diaphorases (tetrazolium reductases) is useful. These three enzymes were used already in 1956 (Stemberg et al.) for the identification and demarcation of single segments of the rat kidney. Differences in their reaction pattern induced systematic electron microscopical investigations, which greatly extended our knowledge. The relatively small number of sheep and cat mesonephroi did not allow the study of further enzymes here, while Wang (1972) was able to study 10 enzymes in the mesonephros of chick, and Jacobsen and Jorgensen (1973b) even 14 in the rat kidney. The occurrence of oxidoreductases in the mesonephroi of the cat and sheep is not mentioned in the literature. In man, Rossi and Reale (1964) found a very low activity of SDH in the nephron. In the frog, Wenk (1966) described the distribution pattern of SDH and NAD-diaphorase: in the first three nephron segments the diaphorase showed a stronger activity than the SDH. In the chick mesonephros, the NAD-diaphorase reaction stained the distal tubules heavily, while the proximal ones only showed a small reaction; the NADP-diaphorase showed an equal reaction in the proximal and distal tubules (Pearse et al., 1963). Mietkiewski and Lukaszyk (1966) report that the reaction of SDH and NAD-diaphorase is similar in the nephron; in the collecting tubule, the reaction is weaker. In a further study (1967) these authors stated that the causes of the decrease in activity of these enzymes during regression of the mesonephros are degenerative processes of the mitochondria and endoplasmic reticulum.