Tight junctions of dissociated and reaggregated embryonic lung cells

Treatment of embryonic lung tissue with trypsin resulted in clustering of intramembrane particles (IMP) and gradual disassembly of tight junctions. In dissociated single cells kept in trypsin-free medium, IMP are randomly distributed but degradation of tight junctions continue. Vesicles containing tight junction elements were observed within the cytoplasm. It is therefore assumed that tight junctions may be degraded in two ways: breakdown of elements to IMP, and endocytosis. In cells reaggregated by rotation tight junctions reassembled only in hystotypic aggregates. Cycloheximide which interferes with histotypic reaggregation prevents the reassembly of tight junctions.