Cholinesterase histochemistry of the rabbit distal colon

Cholinesterases of the gall bladder

Cholinesterase histochemistry of the human gall bladder was studied using two specific methods. Distribution of acetylcholinesterase: In the mucosa, nerve fascicles consisting of densely packed parallel single nerve fibres, small ganglia and "spot"- and "glomerule"- like concentrations of acetylcholinesterase activity were observed. In the muscle layer, a wide-meshed network of delicate nerves, with occational areas of very dense innervation, and small ganglia were seen. In the serosa, "glomerule"- like structures surrounded by dense "baskets" of delicate nerves were observed.-- The general scheme of distribution of non-specific cholinesterases was similar to that of acetylcholinesterase. It seems that the cholinergic innervation of the gall bladder is related to both secretion and absorption and contractility. Some cholinergic nerves are probably sensory, especially because acetylcholinesterase-positive structures, possibly pressure of stretch receptors, supplied with nerves were observed in the mucosa and the serosa. The cholinergic innervation of the gall bladder muscle was scarce except occasional areas of very dense innervation. It may thus be concluded that the intermuscle spread of excitation plays an important role, the majority of the smooth muscle cells receiving their nervous influence via electrotonic coupling.

Innervation of the rabbit rectococcygeus muscle and the functional relationship of the muscle to the terminal large intestine

1. The rectococcygeus muscle is supplied by cholinergic motor fibres from the parasympathetic division of the autonomic nervous system. 2. The histofluorescence technique reveals a sparse adrenergic innervation. 3. When a maintained state of partial contraction is induced by carbachol, stimulation of the extrinsic sympathetic nerves produces a relaxation of the muscle which is usually followed by contraction. 4. The rectococcygeus muscle may also receive nerves which are neither adrenergic nor cholinergic. 5. Ganglion cells have been found close to and, in some preparations, within the muscle; the role of these ganglion cells is not clear. 6. It would appear that the rectococcygeus muscle and the longitudinal muscle of the rectum are not linked by a myogenic mechanism. The rectococcygeus muscle would, however, appear to be linked by nerve fibres to neighbouring structures.

Effects of drugs and of electrical stimulation on the muscularis mucosae of rabbit large intestine

1. The muscularis mucosae of the rabbit large intestine shows spontaneous rhythmic contractions with an average frequency of about 11/minute.2. The muscularis mucosae responds to acetylcholine, adrenaline and noradrenaline in a manner similar to that of whole segments of terminal large intestine.3. The muscularis mucosae would seem to have a cholinergic motor innervation.