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Cell contact and cell adhesion during tissue organization
Author(s) -
Saxén Lauri,
Wartiovaara Jorma
Publication year - 1966
Publication title -
international journal of cancer
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.475
H-Index - 234
eISSN - 1097-0215
pISSN - 0020-7136
DOI - 10.1002/ijc.2910010307
Subject(s) - electron microscope , morphogenesis , intracellular , microbiology and biotechnology , biophysics , lumen (anatomy) , electron micrographs , biology , chemistry , anatomy , motility , optics , biochemistry , physics , gene
The morphogenesis of mouse metanephros has been studied in vitro both in whole organ rudiments and with the aid of experimental recombinations of the inductor and the responding tissue. Time‐lapse cinematography as well as light and electron microscopy were employed to explore cell movements and intercellular contacts during the early steps of tubulogenesis. The first detectable change in the responding mesenchyme is condensation of the induced cells into large aggregates. This is discernible as a cessation of the random motility of the cells, and as a gradual disappearance of the intercellular spaces. In both whole kidney rudiments and experimental recombinants, this stage is followed by secondary fragmentations of the primary aggregates. In whole kidney rudiments, this lobulation always takes place along the midline between two inductively active tips of the branching ureteric tree. Finally, the most central parts of these condensates are pinched off as ball‐shaped pretubular aggregates. Inside these pretubular condensates, cells tend to increase their mutual contact area and to become elongated and radially oriented. Subsequently, connecting membrane units are formed, cells become polarized, and the lumen develops in the centre of the mass. Before this stage, no polarization has been observed in electron micrographs. The subsequent development of the pretubular anlage into the typical S‐shaped body takes place in situ by a continuous partial pinching‐off of the different parts of the loop from the original tissue mass. The observations are discussed in the light of a working hypothesis that an epigenetic inductive stimulus triggers a gradual increase in the mutual adhesiveness in the responding cells. This surface change may explain the primary aggregation and the subsequent lobulation of the condensate. Moreover, aggregation of the cells by reason of this increased adhesiveness may be a prerequisite for polarization inside a certain tissue mass where different parts become exposed to different environmental conditions.