Biology Reference
In-Depth Information
Figure 3.36
The signal cascade for production of surfactant
starts in the brain. In the secretion of the surfactant, the following
are also involved: EGF, via its receptor (EGF-R) (
Dammann
and Nielsen, 1998
); TGFbeta-R; (dihydrotestosterone (DHT);
Damman et al., 2000), as well as thyroid hormones (
DiFiore and
Wilson, 1994
), paracrine hormones parathyroid hormone-related
protein (PTHrP), and leptin (
Torday et al., 2002
).
Source
: From
Cabej (2012)
.
Hypothalamus
Corticotropin-
releasing
hormone
Pituitary
Adreno-
corticotropic
hormone
Adrenal gland
Cortisol
Lung fibroblast
Fibroblast
pneumocyte
factor
EGF
Pneumocyte II
Surfactant
Mechanical strain produced by secreted fluids and diaphragm contractions
induces the release of serotonin, which stimulates the proliferation of lung cells and
formation of alveoli. Neural control in lung development is especially evident in the
induction of surfactant by the alveolar cells of the lung that is essential for survival at
the time of birth (
Figure 3.36
).
Nephrogenesis
By the middle of the twentieth century, Clifford Grobstein (1916-1998), used the
transfilter technique (separation of two interacting tissues by filters) to demonstrate
that the embryonic brain and spinal cord are potent inducers of the differentiation
of the metanephric mesenchyme into epithelial cells and the formation of kidney
tubuli (
Grobstein, 1956
). The brain and the spinal cord maintain this ability only for
a small period during early development. Later, it was found that a secreted glyco-
protein, Wnt-1, released by the CNS (i.e., the spinal cord) was capable of inducing
the nephrogenic transformation of fibroblasts, and it was suggested that nephro-
genesis was induced by the secretion of Wnt-1 by the spinal cord (
Herzlinger et al.,
1994
) (
Figure 3.37
). Other tissues, such as the ureter bud and salivary gland, dis-
play a nephrogenic effect in direct contact with the mesenchymal cells, but only
Search WWH ::
Custom Search