On the ovarian bursa of the golden hamster. II. Intercellular connections in the bursal epithelium and passage of ferritin from the cavity into lymphatics.

Cell abutments in the ovarian bursal epithelium of the golden hamster included tight junctions, desmosome-like junctions, gap junctions and zonulae adhaerentes. The plasma membranes of adjacent epithelial cells were often closely apposed forming a zonula adherens at the apex of the intercellular space, but these did not fuse along the entire length of the intercellular space. Gap junctions and other intercellular junctions did not allow diffusion of ferritin into the junctional areas, but failed to prevent ferritin from filling the intercellular space basal to the junction. This suggested that these junctions were not continuous around the entire circumference of the cell. In general, intercellular connections in the bursal epithelium may be labile and this lability, as well as periodic distention of the bursa, may give rise to separation of epithelial cells. Ferritin injected into the bursal cavity reached lymphatics via three routes: (1) via stomata; (2) via gaps and pores; (3) via intercellular spaces. Transcellular transport did not make a major contribution to permeation of ferritin across the bursal epithelium, and ferritin particles did not enter fenestrated blood vessels within 30 minutes after injection. The variety of routes may facilitate rapid and complete drainage of fluid and cellular components from the bursal cavity.