Cardiac defects associated with the absence of the platelet-derived growthfactor alpha receptor in the Patch mouse

In this report, we describe the distribution of the platelet-derived growth factor receptor alpha (PDGFR alpha) by immunolocalization in the embryonic day 10.5 mouse heart and defects in heart development associated with the absence of this receptor in the Patch mouse. The Patch mouse is a naturally occurring mutant that has been accepted as a model for determining the rol e of the PDGFR alpha in early cardiac development. Even though other geneti c defects exist in this naturally occurring mutant, most defects associated with cardiac development are believed to be a result of the absence of thi s receptor. Gross morphological defects including improper septation of the outflow tract, dysmorphic shape of the heart, and lack of trabecular devel opment are similar to those that have been previously described. Many of th ese defects have been attributed to the failure of a subset of non-neuronal neural crest cells to properly migrate into the region of the developing o utflow tract. In these studies, we have also used confocal scanning laser a nd transmission electron microscopy to describe and compare the organizatio n and differentiation of the cytoskeletal proteins actin and myosin in litt ermate control and Patch mouse hearts. Cytoskeletal organization of the car diac myocytes in Patch mouse hearts has not previously been described. In m ost cardiac myocytes of Patch mice, actin was found only on the periphery o f the cells, and the organization of actin, myosin, and precursor Z-band ma terial into distinct myofibrils was greatly reduced.