Schematic representation of nervous system development of <i>Carinina ochracea</i>.

<p>Serotonin-like (<i>5HT-lir</i>) and FMRFamide-like (<i>RFa-lir</i>) immunoreactivity are color coded in magenta and green respectively; the general nervous system architecture as outlined by synapsin-like immunoreactivity (<i>syn-lir</i>) is shown in grey. All larval stages are drawn to scale with apical tuft (<i>at</i>), epidermal cilia, fronto-lateral epidermal invaginations (<i>fi</i>), midgut (<i>mg</i>), mouth opening (<i>mo</i>), and the pigmented larval eye (<i>pe</i>) serving as landmarks (cilia of the frontal epidermal invaginations, the stomodaeum, the midgut, and epidermal cilia in the aspect of view omitted), apical is up. A and B: left: lateral view from right, right: ventral view. Transitory neuronal/neuritic elements are indicated by stippling/dotted lines. A: Post-gastrula stage larva at one day post-fertilization (<i>1-dpf</i>). B: Larva at <i>2-dpf</i>. C: Larva at <i>3-dpf</i>. From left to right: lateral view from right, ventral view, dorsal view, lateral view from left. Since the nervous system is roughly symmetrical, only one side is shown (left: 5HT-lir, right: RFa-lir). For clarity, the peripheral plexus is not shown. Further explanations, see text.–<i>bd</i>, dorsal brain neuron; <i>br</i>, brain-ring; <i>bv</i>, vental brain neuron; <i>an1</i>, 1^st apical median (transitory) neuron; <i>an2</i>, 2^nd apical medio-ventral (transitory) neuron; <i>nc</i>, lateral nerve cord; <i>cn1</i>, 1^st caudal median (transitory) neuron; <i>cn2</i>, 2^nd caudal medio-dorsal (transitory) neuron; <i>nm</i>, dorso-median neurite mass.