ABSTRACT
Whole-mount preparations of guinea-pig small intestine and gall bladder stained using a modified Giemsa technique were used to estimate neuronal and ganglion density, and neuron area, within the wall of these organs. The myenteric ganglia were long and thin in the jejunum and ileum, and round, triangular, square, rectangular or distinctly elongated in the duodenum. Most of the myenteric neurons were also elongated. The submucosal plexus showed a remarkable regularity of pattern, and, compared with the myenteric plexus, had smaller ganglia which were variable in shape. The pattern of the intramural plexus resembles that of the submucosal plexus. In the myenteric plexus, there were no differences in ganglion density among the duodenum, jejunum and ileum. Neuronal density and the number of neurons/ganglion was greater in the duodenum. The mean ganglion and neuronal densities in the submucosal plexus were greater in the ileum and smaller in the jejunum. The number of neurons/ganglion decreased from the duodenum to the ileum. The intramural plexus of the gall bladder contained 1 ganglion/mm2 and 6 neuron/mm2. In the myenteric plexus, neuron area ranged from 101 to 250 mum2; in the submucous plexus, the value was from 51 to 250 mum2 while in the intramural plexus, the areas of most neurons lay in the ranges of 201 to 300 mum2 and 301 to 400 mum2. These results suggest significant differences in neuronal density in the myenteric plexus among the duodenum, jejunum and ileum, and significant differences between the submucosal and intramural plexuses.