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 –
�crosstalk�
�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