Skip Navigation
Stage 1 / 1 day Stage 2 / 2-3 days Stage 3-1 / 4 days Stage 3-2 / 4-5 days Stage 4 / 6 days Stage 5a-1 / 7 days Stage 5a-2 / 8 days Stage 5b / 9 days Stage 5c / 12 days Stage 6 / 13-17 days Stage 7 / 16-19 days Stage 8 / 23 days Stage 9 / 25 days Stage 10 / 28 days Stage 11 / 29 days Stage 12 / 30 days Stage 13 / 32 days Stage 14 / 33 days Stage 15 / 36 days Stage 16 / 39 days Stage 17 / 41 days Stage 18 / 44 days Stage 19 / 45-47 days Stage 20 / 49 days Stage 21 / 49-52 days Stage 22 / 52-55 days Stage 23 / 56 days
Atlas of Human Embryos Chapter   Figure

Cranial edge of primitive pharynx, anterior cerebral plexus, aortic arch 2, basis pedunculi area, dorsal aorta, glossopharyngeal preganglion (CN IX), hypoglossal nerve (XII), internal carotid artery, junction of neural crests XI and X, maxillomandibular part of trigeminal neural crest, median sulcus, notochord, occipital dermatome, ophthalmic part of trigeminal neural crest, pharyngeal arch 1, pharyngeal groove 1, pharyngeal pouch 1, placode 7, placode 9-10, precardinal vein, rhombencephalon (hindbrain), sulcus limitans, tectum, tegmentum, vagal preganglion (CN X)

A section through the mesencephalon, rhombencephalon and cranial edge of the primitive pharynx.

Observe:
1. The internal carotid artery, which is the rostral continuation of the dorsal aorta.
2. The first and second branchial arches separated by the first branchial groove.
3. The close association of the preganglia to the ectoderm.
4. The close association of the glossopharyngeal preganglion to placode IX-X.
5. The three parts of the definitive mesencephalon: tectum, tegmentum and basis pedunculi area.


Keywords: Cranial edge of primitive pharynx, anterior cerebral plexus, aortic arch 2, basis pedunculi area, dorsal aorta, glossopharyngeal preganglion (CN IX), hypoglossal nerve (XII), internal carotid artery, junction of neural crests XI and X, maxillomandibular part of trigeminal neural crest, median sulcus, notochord, occipital dermatome, ophthalmic part of trigeminal neural crest, pharyngeal arch 1, pharyngeal groove 1, pharyngeal pouch 1, placode 7, placode 9-10, precardinal vein, rhombencephalon (hindbrain), sulcus limitans, tectum, tegmentum, vagal preganglion (CN X)

Source: Atlas of Human Embryos.