Y. Takaku et al., The process of cell adhesion among dissociated single cells of Hydra: Morphological observations, J EXP BIOL, 204(10), 2001, pp. 1697-1702
Ultrastructural observations were made on the initial adhesion process at t
he adherent region of Hydra endodermal cell pairs brought into contact (fol
lowing dissociation) using a three-dimensional laser manipulator. Total con
tact length across the diameter of the adherent region decreased during the
period 10-60 min after initial adhesion. However, the mean numbers of clos
est (<4 nm) and medium (5-25 nm) separation distances between membranes (th
ought to be important in total cell adhesion) were not significantly differ
ent. These data indicate that adherent cell pairs maintain a constant adhes
iveness during the first 60 min of the adhesion process, despite membrane r
earrangements. The relative length of each separation distance in adherent
cell pairs approached that reported previously for intact Hydra. The sums o
f lengths in both the closest and medium categories (as a proportion of tot
al contact length) increased because the length of cleavages (distances > 2
5 nm) decreased significantly during the same time period. These results su
ggest that adherent cell pairs undergo rapid, active membrane changes in th
e adherent region, which might be associated with cell sorting. The possibl
e significance of these changes for active rearrangement are discussed.