Cellular junctions in perifollicular contractile tissue of the rat ovary during the preovulatory period.

Rat ovarian perifollicular contractile tissue was examined at specified intervals prior to ovulation to determine the type, relative number, and length of cellular junctions. Rat ovaries were taken for electron-microscopic observation at 1500 h on the afternoon of proestrus (proestrus 0-h group), at 2000 h (proestrus 5 h group), at 0100 h (proestrus 10-h group) and at 1600 h on the afternoon of diestrus I. Close junctions, intermediate junctions, and gap junctions were counted and measured. Then number of gap junctions/1,000 micrometers of membrane and the number of intermediate junctions/1,000 micrometers of membrane was significantly higher in the proestrus 10 h groups as compared to the other groups. There was no difference in the number of close junctions during the periods studied. Also the length of all junctions was similar in all groups. These morphological findings are discussed in the context of contractile role for perifollicular tissue in the ovulatory process.