The localization of acetylcholinesterase at the autonomic neuromuscular junction

Acetylcholinesterase has been localized at the autonomic neuromuscular junction in the bladder of the toad (Bufo marinus) by the Karnovsky method. High levels of enzyme activity have been demonstrated in association with the membranes of cholinergic axons and the adjacent membranes of the accompanying Schwann cells. The synaptic vesicles stained in occasional cholinergic axons. After longer incubation times, the membrane of smooth muscle cells close to cholinergic axons also stained. Axons with only moderate acetylcholinesterase activity or with no activity at all were seen in the same bundles as cholinergic axons, but identification of the transmitter in these axons was not possible.

Use of the direct-coloring thiocholine technique for demonstration of intracellular neuronal cholinesterases

A study has been made of factors influencing the effectiveness of the "direct-coloring" thiocholine technique in demonstrating intracellular cholinesterases in motor neurons. It has been found that certain procedures likely to produce disruption of the neuronal membrane are necessary for efficient penetration of the ferricyanide component of the staining medium. The procedures used were osmotic shock and brief freezing of the tissue. The results are discussed with regard to application of the direct-coloring technique to electron-microscopy.

Physicochemical characteristics of active and arrested carious lesions of dentin

SYNOPSIS IN INTERLINGUA

CHARACTERISTICAS PHYSIO-CHIMIC DE ACTIVE E ARRESTATE LESIONES CAEIOSE.—Le duo plus obvie differentias clinic inter dentinas a cariositate arrestate e active es le augmentos del duritate superficial e del pigmentation in le lesiones arrestate. Analyses per medio de un specialmente disveloppate technica a absorption infrarubie monstrava un augmento del contento organic e un declino del contento inorganic in dentina cariose, sed le methodo provideva nulle information relative al natura del pigmento in le dentina a cariositate arrestate. Analyses spectral a flamma revelava in dentina a cariositate arrestate in comparation con dentina a cariositate active un augmento de Ca++ per un factor de 1,64. Le mesme methodo monstrava que le dentina a cariositate arrestate habeva minus Ca++- que dentina normal.