Description of the structural control systems of ovum transport in the quail oviduct

The membrane potential of the Japanese quail's oviductal smooth muscle during ovum transport

Previously it has been shown that in the quail's oviductal smooth muscle there exists coordinated electrical and mechanical activity. It is not known how the contractions are regulated; the oviduct probably functions as a stretch receptor and the mechanical stimulus is produced by the ovum itself. The cellular basis for stretch-induced contractions is not known. In strips (n = 8) from the magnum, stretches of 50% changed the membrane potential. Compared with the resting length L0 (= 100%), stretches to 150% and 200% significantly (p less than 0.001) hyperpolarized the membrane potential. Analyses of variance, however, revealed that at the length 150% both the level of stretch and single experiments differed significantly in relation to the membrane potential: F = 7.1, p less than 0.5; F = 14.6, p less than 0.01, respectively. At the length 200%, there were highly significant differences between the groups 100% and 200% (F = 36.3, p less than 0.001) but the differences could be explained by the highly significant (F = 13.9, p less than 0.001) interaction. Membrane potential measured from isolated, intact oviducts (n = 7) which had ovum in the magnum was significantly depolarized by 8-9 mV on the region over the ovum. On the other hand, the membrane potentials were the same in the different segments of the oviduct which did not contain an ovum: 52 mV.(ABSTRACT TRUNCATED AT 250 WORDS)