Endocardial cushion tissue development: structural analyses on the attachment of extracellular matrix to migrating mesenchymal cell surfaces.

R. R. Markwald, J. M. Krook, G. T. Kitten, R. B. Runyan

Research output: Contribution to journalReview article

31 Scopus citations

Abstract

The progressive growth and eventual fusion of the atrioventricular (AV) endocardial cushions is of critical importance to normal embryonic heart development. Failure to do so would result in septal and AV valvular defects. A central feature in initial cushion growth is the migration of cushion tissue (CT) cells through an heterogeneous extracellular matrix (ECM) which has previously been shown (in particular hyaluronate) to modify migratory behavior. Attention was directed to migrating CT cells to determine if (1) their surfaces physically attach to or bind ECM and (2) are modified to suggest a morphological basis for cell:matrix interaction. The migratory appendages (filopodia) of CT cells maintained in organ culture attached both to collagenous microfibrils coated with polyanionic material and hyaluronate (HA) enriched ECM. The cell:matrix associations were of sufficient strength to restrain the cell from contracting following freezing procedures and were labile to mild trypsin treatment. HA enriched matrix persisted at the cell surface even after treatments which removed most free ECM, but was readily removed by hyaluronidase and trypsin digestion. Freeze fracture analyses revealed 16-18 nm particles elevated above the plane of the filopodial surface which closely interfaced with ECM components. These particles were variably distributed, ranging from almost homogenous dispersion to focalized clusters, but were absent on surrounding non-migratory (myocardial) cells. Results are consistent with a model in which cell attachment to its migratory substratum is mediated by polyanions (probably sulfated glycosaminoglycan and fucosylated glycoprotein) and detachment by hyaluronate.

Original languageEnglish (US)
Pages (from-to)261-274
Number of pages14
JournalScanning electron microscopy
Issue numberPt 2
StatePublished - Dec 1 1981
Externally publishedYes

ASJC Scopus subject areas

  • Control and Systems Engineering
  • Biophysics

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