Factors in branching
morphogenesis
_Proliferation
§Growth factors, factors
that promote pluripotency
_Differentiation
§Transcription
factors and downstream effectors leading to different cell types
§Proximal and distal
differences (e.g cartilage, type II cells)
_Inhibition of proliferation
§Growth eventually stops,
also a key to branch points
_Apoptosis
§Structures must be
remodeled in second wave of growth.
§May deal with local
proliferation excess.
_Coordinated growth of different cell populations –
ÒcrosstalkÓ
§Elements may
be intracellular pathways, cellular receptor specificity, as well as diffusable factors with
very local gradients
_Differential adhesion.
§Cell to cell, cell to
matrix.
§Adhesion
molecules may be expressed reducing cellular fluidity, fostering attachment of epithelium to
mesenchyme via common extracellular matrix proteins