Table 1. Comparison Erbb2 null [22], [25] and l11Jus8 phenotypes.

	Erbb2 null	l11Jus8 -/-
lethality	E10.5- E11.0	E12.5-13
general	degeneration of motor nerves, absence of Schwann cells, impairment of junctional folds at the neuromuscular synapse	no gross morphological internal organ defects
cardiac	absent myocardial trabeculae, thin ventricular wall, enlarged heart, poor circulation, irregular heartbeat, lack of cardiac ventricular myocyte differentiation, decreased endocardial cushion size	no ventricular, AV cushion or OFT defects, thickened, folded atrial myocardium which becomes stretched when atria stop contracting, atria inflated with blood, haemorrhage, heart rate normal but abruptly ceases without progressive decline