A section through the dorsal edge of the optic cup and primitive pharynx.
Observe:
1. The choroid invagination into the lateral ventricle and the relation of the primordial hippocampus and its cortex to the choroid fissure.
2. The junction of the optic stalk and diencephalon.
3. The hypophyseal stem remnant passing through the hypophyseal cartilage.
4. The mandibular nerve terminating in the muscles of mastication.
5. The condensations representing the malleus and incus ossicles between the external acoustic meatus and primitive tympanic cavity.
Keywords: C-1 ventral primary ramus, C-2 spinal ganglion, anterior cerebral artery, auditory tube, cartilage of branchial arch 2, choroid fissure, choroid invagination, ependymal layer, external acoustic meatus, external layer of optic cup, extraocular muscle, facial nerve, hypoglossal nerve (CN XII), hypophyseal cartilage, hypophyseal stem remnant, inferior ganglion of glossopharyngeal nerve (CN IX), internal carotid artery, intraretinal space (optic vesicle cavity), junction of optic stalk and diencephalon, lateral ventricle, malleus and incus, mandibular nerve (CN V₃), mantle layer, marginal layer, middle cerebral artery, muscles of mastication, notochord, primitive pharynx, primitive supraorbital vein, primitive tympanic cavity, primordial cornu Ammonis, primordial gyrus dentatus, primordial hippocampus, splenius muscle, upper eyelid fold, vagus nerve (CN X), ventral median sulcus, vertebral artery
Source: Atlas of Human Embryos.