Figure 7

Development of early fiber tracts in the brain of E. coqui ( A - C ) and D. pictus ( D-F ) as revealed by immunohistochemistry for acetylated tubulin. Asterisks indicate the optic stalk in all panels. A, D: The tract of the postoptic commissure and its associated commissure are the first fiber tracts to form in the embryonic forebrain of both species (boxed area in A is shown at a more lateral level of focus). B, E: At midembryonic stages, a more complex scaffold of tracts has formed. C, F: Camera lucida drawings of embryos with all major fiber tracts indicated. In E. coqui, fibers run ventrad along the lateral surface of the thalamus, but no dorsoventral diencephalic tract of tightly bundled fibers is observed (indicated as "DVDT ?"). Abbreviations: AC: anterior commissure; Cer: cerebellum; CPT: commissure of the posterior tuberculum; DVDT: dorsoventral diencephalic tract; Ep: Epiphysis; HC: Habenular commissure; ITC: intertectal commissure; NII: optic nerve; NV: trigeminal nerve; NVII/VIII: facial and vestibulocochlear nerves; PC: posterior commissure; POC: postoptic commissure; Ret: retina (hatched circle); SOT: supraoptic tract; TAC: tract of the anterior commissure; THC: tract of the habenular commissure; Tel: telencephalon; TO: optic tectum; TCC: tract of the cerebellar commissure; TCPT: tract of the commissure of the posterior tuberculum; TPC: tract of the posterior commissure; TPOC: tract of the postoptic commissure; TV: descending tract of the trigeminal nerve; TVTC: tract of the ventral tegmental commissure; TVIII: descending tract of the vestibulocochlear nerve; VLT: ventral longitudinal tract. Bar: 100 μm in all panels.