83.The answer is c.(Alberts, pp 1066–1078. Young, pp 86–89. Junqueira,
p 70. Ross and Pawlina, pp 130–131.)The hemidesmosome interacts with the
extracellular matrix molecules within the basal lamina through intermediate
filament proteins. The hemidesmosomes combined with the desmosomes act
to distribute tensile forces through the epithelial sheet and the supporting
connective tissues. For information on gap junctions see the answer for
question 75. Junctional complexes are summarized in the table below.
168 Anatomy, Histology, and Cell Biology
Occluding Zonula Prevents passage Intramembranous
occludens of luminal sub- sealing strands
(tight junction) stances; confers occlude the space
epithelial tight- between cells (# of
ness or leakiness; strands directly
maintains apical proportional to
vs. basolateral tightness of epithe-
polarity lium)
Anchoring Zonula adherens Mechanical Link actin filament
stability—cohesive network be-
function of cell tween cells,
groups, important cadherins are
during embryonic transmembrane
folding; transmits linkers
motile forces across
epithelial sheets
Focal contacts Attach cells to the Link actin filament
ECM network of cell to
integrins in ECM;
actin-binding proteins
form link
Anchoring Desmosome Spot welds (rivets) Link intermediate
(macula provide high filaments to
adherens) tensile strength transmembrane
and resist proteins (cadherins:
shearing forces, desmogleins and
numerous in desmocollins).
stratified Linkage through
squamous plaque proteins
epithelia (desmoplakins)Classification Type Function Interactions(Continued)