Development of the Early Axon Scaffold in the Rostral Brain of the Small Spotted Cat Shark (Scyliorhinus canicula) Embryo

Figure 3

Description of the early axon scaffold at stage 25 in the embryonic S. canicula brain. Lateral view of whole mount embryonic brain. Scale bars, 100 μm. (a) Overview of the early axon scaffold at stage 25. All axon tracts were well established. Boxes indicate magnified images in (b) and (c). (b) Prosencephalon. The TPOC, SOT, and THC were well established. An unidentified tract (1) was located caudally in the diencephalon. The neurones were possibly located at the ventral midline (small arrowhead). (c) Unidentified tract 1 appeared to be projecting dorsally before turning to project slightly caudally. Possible MTT neurones were projecting axons ventrally (filled arrow). The TPOC axons have turned at a right angle and project ventrally (arrowhead). AC: anterior commissure; ADt: anterior dorsal telencephalic neurones; DTmesV: descending tract of the mesencephalic nucleus of the trigeminal nerve; ep: epiphysis; LLF: lateral longitudinal fascicle; mes: mesencephalon; MLF: medial longitudinal fascicle; op: olfactory pit; PC: posterior commissure; pros: prosencephalon; rh: rhombencephalon; SOT: supraoptic tract; tel: telencephalon; THC: tract of the habenular commissure; TPC: tract of the posterior commissure; TPOC: tract of the postoptic commissure; V1: ophthalmic profundus nerve; VC: ventral commissure; III: oculomotor nerve.