Fig. 2. Aberrant position and impaired innervation of the SCG in newborn Ret-/- mice. (A,B) Parasagittal section of newborn mouse head stained with Hematoxylin and Eosin (rostral part is on the left). The SCG (white arrowheads) is located far caudal to its normal location near the bifurcation of the carotid artery (black arrows) in Ret-/- mouse. (C) Whole-mount TH immunohistochemistry showing connection of the SCG to the STG (arrowhead) by the cervical sympathetic trunk (white arrow). (D) Ganglion volume of the SCG. Closest vertebral level to the center of the ganglion is shown by x-axis. WT1,2, wild type; KO, Ret-/- mice; R, right SCG; L, left SCG. Note that the location and the volume vary between the right and left side of the same animal (KO1R versus KO1L, KO2R versus KO2L). (E,F) SCG neurons of Ret-/- mice are often small and display immature morphology. (G-J) The internal carotid nerve (white arrows) is abnormally branched and fails to travel rostrally in Ret-/- mice. Dotted circles depict the inner ear. (I,J) Dorsal view of the newborn head, showing total absence of the internal carotid nerve. The brain was removed in this preparation. (K,L) Absence of TH-positive fibers in the peripheral lobe of the submandibular gland of Ret-/- mice. Scale bar: 2 mm in A,B; 600 µm in C; 550 µm in E,F; 1 mm in G,H; 1.7 mm in I, J.
