Traversing filaments in desmosomal and hemidesmosomal attachments: freeze-fracture approaches toward their characterization.

Desmosomes and hemidesmosomes from larval newt epidermis were examined by freeze-fracture methods incorporating low osmolality fixation, short duration glycerination, complementary replica comparison, stereo imaging, and dark shadow printing. These procedures provide new evidence regarding the structure of "traversing" filaments as mediators of attachment between intermediate filaments and the cell membranes of desmosomes and hemidesmosomes. A detailed analysis of intramembranous particles and other structures in these attachments has also been possible. The relationship of this evidence to models of desmosomal structure suggested by other authors is discussed.