Biology Reference
In-Depth Information
FIGURE 20.7
The mammalian branching systems that have received most attention, superimposed on draw-
ings made by the anatomist Versalius in 1542. This diagram is reproduced by kind permission of BioEssays, where it
first appeared.
for the MDCK cell model. MAP kinase activation is required for branching morphogenesis in
organs in which a requirement has been tested, which include the salivary glands,
35
lungs
and kidneys, where MAP-kinase drives mitosis.
36
e
38
The PI-3-kinase pathway is required
for branching in salivary glands
39,40
and kidneys.
41
Smad activation by the TGF
b
family of
FIGURE 20.8
The difference between the morphology of tracheal branching in
D. melanogaster
, where new
sprouts tend to be led by dingle cells, and in the ureteric bud, a typical mammalian branching epithelium in which
branch tips are composed of several cells. The tracheal drawing is based on data presented in Uv et al.
105
and the
ureteric bud from an electron micrograph in Saxon.
106
