Histochemical studies of alkaline phosphatases in the tissues of the rat using frozen sections. I. Substrate specificity of enzymes hydrolyzing poly-glycol-mono-phosphate esters, hexose-diphosphate, and -naphthylphosphate

Localized areas of high alkaline phosphatase activity in the terminal arterial tree

Fresh frozen skeletal muscles of rats, rabbits, and humans were sectioned in a cryostat. Sections 12 to 32 micra thick were incubated in a substrate solution for the histochemical demonstration of non-specific alkaline phosphatase activity. A modified azo dye coupling technique was used at pH 9.5. Localized areas of high enzymatic activity were found in specific and well defined areas along the terminal arterial tree, in addition to the activity which has been previously described in capillary endothelium. Arterial branches with luminal diameters of 25 micra or less showed staining of their endothelium starting abruptly at their origin from the parent vessel and fading distally. Smaller arterial branches showed the same localization of enzymatic activity and stained more intensely. Other organs of rats surveyed showed arterial branches with the same pattern of staining. Identical results were obtained using the Gomori technique for alkaline phosphatase. Extensive saline perfusion of the vascular tree did not affect the observed localization of enzymatic activity. The enzymatic activity described may be part of the mechanism regulating the blood flow.

Blood vessels and connective tissue in autotransplanted free muscle grafts of the cat

After 2 weeks of denervation, whole leg muscles of adult cats were transplanted to intercostal spaces and removed at intervals from 5 days to 44 weeks after grafting. The connective tissue formation and capillary supply of the grafts were studied histologically and histochemically for connective tissue and ATPase. In addition, normal muscles, denervated muscles left in situ, and muscles transplanted without previous denervation were studied. During the denervation period of 2 weeks the capillary network increased slightly. During the first 6 weeks after grafting only a few, thick-walled, irregularly shaped capillaries were present in the grafts. At 8-12 weeks there was a pronounced increase in the vascular supply, coincident with reinnervation of the grafts, and after 40 weeks the capillary pattern appeared fairly normal. In the early stages a marked increase in perimysial and endomysial connective tissue took place. With increasing reinnervation a gradual disappearance of the endomysial connective tissue occurred and in the most mature grafts a minimal increase of perimysial connective tissue remained. In muscles transplanted without previous denervation, extensive fibrotic changes developed.

Localization of D-myoinositol 1:2-cyclic phosphate 2-phosphohydrolase in rat kidney

1. On subcellular fractionation of rat kidney homogenates by differential and density-gradient centrifugation, the bulk of the inositol 1:2-cyclic phosphate 2-phosphohydrolase activity remains with the alkaline phosphatase activity, suggesting localization in the brush borders of the proximal tubules. 2. Histochemical studies with a medium containing inositol 1:2-cyclic phosphate and Escherichia coli phosphomonoesterase show Gomori staining around the brush borders of the proximal tubules in the outer cortex only. 3. Serial sections across the kidney from cortex perimeter to papilla suggest that the inositol 1:2-cyclic phosphate 2-phosphohydrolase has a limited distribution along the proximal tubule of the nephron, probably being limited to the pars convoluta, whereas the alkaline phosphatase extends along the pars recta.

THE LOCALIZATION OF ALKALINE PHOSPHATASE ACTIVITY IN CEREBRAL BLOOD VESSELS

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