A Study of Nexuses in Visceral Smooth Muscle

Nexuses are described between the smooth muscle cells of the gizzard of the chick and the pigeon, the vas deferens of the mouse and the guinea pig, and the taenia coli of the guinea pig. The nexuses in the gizzard were examined after osmium tetroxide and potassium permanganate had been used as fixatives. Although differences in the dimensions of the unit membranes and the nexuses were noted, the results with the two fixation techniques were complementary. The distribution of nexuses within the smooth muscle tissues examined was uneven. Nexuses were still present in both small and large pieces of tissue incubated in hypertonic solutions at varying temperatures. Other experiments showed that the degree of contraction at the time of fixation did not affect the presence of nexuses in the tissue. These results indicate that nexuses between smooth muscle cells are stable under a variety of conditions.