Pharyngeal morphology in <i>Tbx1</i> and <i>Tie2Cre/Nrp1</i> mutants.

<p>All panels are frontal sections of E10.5 embryos. <b>A</b>,<b>B</b>, control and littermate <i>Tbx1</i> null embryos; the <i>Tbx1</i> mutant has no segmentation of the foregut (FG) pharyngeal endoderm. <b>C</b>,<b>D</b>, control and littermate <i>Tie2Cre/Nrp1</i> mutant, showing normal pharyngeal organization in mutant embryos even when arch arteries are missing (in the mutant, both 4^th arch arteries were extremely hypoplastic, indicated by the asterisks). 3p, 4p, 3^rd and 4^th pharyngeal pouches; numbers indicate pharyngeal arch arteries. A histology artifact is responsible for the broken piece of the left 3^rd arch in the mutant shown.