Cholinesterases and cell proliferation in "nonstratified" and "stratified" cell aggregates from XXXX retina and tectum.

@entity1573 @entity969 @entity13522 @entity33589
Dissociated single cells from @entity1573 retina or tectum kept in rotation-mediated cell culture aggregate, proliferate and establish a certain degree of histotypical cell-to-cell relationships ("sorting out"), but these systems never form highly laminated aggregates ("nonstratified" R- and T-aggregates). In contrast, a mixture of retinal plus pigment epithelial cells forms highly "stratified" aggregates ("RPE-aggregates", see Vollmer et al. 1984). The present comparative study of "stratified" and "nonstratified" aggregates enables us to investigate the process of cell proliferation uncoupled from that of tissue stratification. Here we try to relate these two basic neurogenetic processes with patterns of expression of cholinesterases ( @entity13522 , @entity33589 ) during formation of both types of aggregates. During early aggregate formation, in both "stratified" and "nonstratified" aggregates an increased butyrylcholinesterase activity is observed close to mitotically active cells. Quantitatively both phenomena show their maxima after 2-3 days in culture. In contrast, @entity13522 -expression in all systems increases with incubation time. In nonproliferative areas, in the center of RPE-aggregates, the formation of plexiform layers is characterized initially by weak @entity33589 - and then strong @entity13522 -activity. These areas correspond with the inner (IPL) and outer (OPL) plexiform layers of the retina in vivo. Although by @entity969 gradient centrifugation we find that the 6S- and the fiber-associated 11S-molecules of @entity13522 are present in all types of aggregates, during the culture period the ratio of 11S/6S-forms increases only in RPE-aggregates, which again indicates the advanced degree of differentiation within these aggregates.(ABSTRACT TRUNCATED AT 250 WORDS)
