Cell contacts in rabbit corpora lutea

Abstract

The cell contacts in corpora lutea of pseudopregnant rabbits were studied in normally processed and in lanthanum treated tissue. Gap junctions and septatelike cell contacts were detected and are described in this paper. The gap junctions are pentalaminar or show a 20 Å gap after uranyl staining “en bloc.” Tangentially cut gap junctions in lanthanum treated tissue show the generally known tightly packed intercellular particles. In septatelike cell contacts the cell membranes are separated from each other by a 160–180 Å wide intercellular space and the contact is made by repeating electron lucent septa. After colloidal lanthanum application the cross-sectioned cell contacts also show repeating structures with a periodicity ranging from 80–95 Å. These structures seem to be composed of a larger particle in the middle and symmetrically arranged smaller particles at both sides near the cell membrane. The “en face” view shows clear granules in a dark background. These granules and also their distribution are, however, clearly different from the particles seen in gap junctions. These findings are compared with earlier results on septatelike cell contacts and the presumed function of these septatelike cell contacts is discussed.