Uberon definition : A thick plate of mesodermal tissue that occupies the space between the thoracic cavity
and yolk stalk in the early embryo, forming a transverse partition partially separating
the coelomic cavity into thoracic and abdominal portions. It gives rise to the central
tendon of the diaphragm[VHOG].;
Uberon synonym : transverse septum;
Uberon Development note : The cranial part of the septum transversum gives rise to the central tendon of the
diaphragm and is the origin of the myoblasts that invade the pleuroperitoneal folds
resulting in the formation of the muscular diaphragm. The caudal part of the septum
transversum is invaded by the hepatic diverticulum which divides within it to form
the liver and thus gives rise to the ventral mesentery of the foregut.;
Uberon Homology note : In hagfishes a transverse septum extends upward from the ventral body wall posterior
to the heart, partly separating an anterior pericardial cavity from a larger peritoneal
cavity. (...) These basic relationships have not been modified by urodeles. The small
pericardial cavity remains far forward where it is separated by a transverse septum
from the principal coelom, which may now be called a pleuroperitoneal cavity because
slender lungs are present. (...) The heart (of other tetrapods) is separated from
the lungs (and liver if present) by more or less horizontal partitions that have their
origin in the embryo as folds on the serous membrane of the right and left lateral
body walls. These grow out to join in the midline of the body. They are called lateral
mesocardia (birds) or pleuropericardial membranes. Posteriorly they join the transverse
septum to form the adult pericardial membrane, or pericardium. (...) In their partitioning
of their coelom, embryonic mammals resemble first early fishes (incomplete partition,
posterior to heart, consisting of the transverse septum) and then reptiles (pericardium
derived from transverse septum and pleuropericardial membranes) Mammals then separate
paired pleural cavities from the peritoneal cavity by a diaphragm. The ventral portion
of this organ comes from the transverse septum. The dorsal portion is derived from
the dorsal mesentery and from still another pair of outgrowths from the lateral body
wall, the pleuroperitoneal membranes.[well established][VHOG];
A thick plate of mesodermal tissue that occupies the space between the thoracic cavity
and yolk stalk in the early embryo, forming a transverse partition partially separating
the coelomic cavity into thoracic and abdominal portions. It gives rise to the central
tendon of the diaphragm[VHOG].