Probit analysis of the atrioventricular (AV) junctional tissues of the ferret heart.

Probit frequency analysis, a graphic method for determining whether a population is normally distributed, skewed, or multinodal, was used to determine whether P cells are present in different regions of the AV junction in the ferret heart. This analysis indicated that at least 95% of the cells of the transitional zone, superficial AV node, deep AV node, and distal AV bundle of the ferret heart are morphologically homogeneous. In the proximal AV bundle a large cell population is found in addition to the AV bundle cells. The probit analysis was also used to characterize the shape of the cells of each region of the AV junction further. AV nodal cells are not as elongated as the atrial muscle cells and AV bundle cells. These nodal cells also do not branch as extensively as the AV bundle cells.