Fig. 5
From: Peripheral sensory neurons govern development of the nervous system in bivalve larvae
(Schematic drawings adapted by Olga Kharchenko from Yurchenko et al. [14])
Arrangement of neurons expressing different transmitters at the veliger stage of the bivalve mollusk Crassostrea gigas. Only the right side of the body is shown. FMRFamide-immunoreactive fibers first grow dorso-ventrally and then turn posteriorly. 5-HT-ir fibers grow in anterior-to-posterior direction from the apical organ (AO), while VAChT-ir grows in the posterior-to-anterior direction towards the AO. Altogether, these processes form a compact neurite bundle along the ventral side of the larval body. The right and left bundles run in parallel on the respective sides of the larval body, organizing rudiments of the paired lateral nerve cords. AO apical organ, dn dorsal neurons, vn ventral neurons, pn posterior neurons