Expression and deposition of fibrous extracellular matrix proteins in XXXX during @entity1573 development.

@entity154 @entity1131 @entity1573 @entity299 @entity340
Extracellular matrix (ECM) plays essential signaling and structural roles required for the proper function of @entity299 . Cardiac valves initially form as jelly-like cushions, which must adapt to withstand the increased circulation hemodynamics associated with fetal development and birth. This increased biomechanical stability of the developing valves is largely imparted by ECM proteins, which form a highly organized fibrous meshwork. Since @entity340 contribute to most congenital @entity299 , understanding valve development will provide insight into the pathogenesis of various @entity154 . Thus, the goal of this study is to describe the spatiotemporal deposition of fibrous ECM proteins during cardiac valve development. @entity1573 embryonic and fetal @entity340 were examined by light, confocal, and transmission electron microscopy (TEM). Our data demonstrate that fibrous ECM proteins are deposited when the leaflets are adopting an elongated and compacted phenotype. A general pattern of increased fibrotic ECM deposition was detected in valve tissues. Also, each ECM protein examined displayed a unique pattern of organization, suggesting that regulation of fibrous @entity1131 is complex and likely involves both genetic and mechanical factors. In addition, the TEM study revealed the presence of membrane protrusions from @entity340 , indicating a potential mechanism for mechanical force transduction.
