A section through the C-2 neural crest, middle of the optic vesicle and cranial edge of the heart.
Observe:
1. The slightly thickened ectoderm (lens placode) adjacent to the optic vesicle.
2. The communication between the prosocoele and the optic cavity.
3. The median mandibular groove between the ventral end of the mandibular processes.
4. The cranial edge of the pericardial cavity and the right and left atria separated by the septum primum.
5. The cranial part of the tracheoesophageal tube where the larynx will develop.
Keywords: C-1 myotome, C-2 myotome, C-2 neural crest, anterior cerebral plexus, chiasmal part of hypothalamus, communication between prosocoele and optic cavity, left atrium, lens placode, mandibular prominence of pharyngeal arch 1, median mandibular groove, notochord, optic vesicle, pericardial cavity, pharyngeal arch 2, right atrium, septum primum, tracheo-esophageal tube, truncus arteriosus
Source: Atlas of Human Embryos.