A section through the tectum of the mesencephalon and edge of the metencephalon.
Observe:
1. The dorsal part of the mesocoele and fourth ventricle.
2. The dorsal part of the middle cerebral plexus of veins in the ectomeninx.
Keywords: ectoderm, ectomeninx, edge of metencephalon, endomeninx, mesocoele (midbrain ventricle), mesoderm, middle cerebral plexus, rhombencoel (fourth ventricle), tectum of mesencephalon (midbrain)
Source: Atlas of Human Embryos.