The chondrocranien hof 2 human embryos, 22mm and 35mm long, were studied.In both embryos the cranial nerves and the belonging ganglions are completely developed, themuscles of thebulbus oculi also, circulus arteriosu sandsinus durae, are also.completed.Itisstrange that the thickt sympathic llerves which follow a.carotis interna becomes invisible abruptly near the surface of the brain.
1. In the hind part of the occipital cartilage there is a thin (22mm) or broad(35mm)bridge tectum posterius;moreover in the35mm long the tectum intermedium, of Fawcett and the right.tectum anterius visible, in the 22mm long not yet.
2. The processus paramastoideus, which is the ventral prolongation of the lamina alaris, is in 35mm long cartilageous, in 22mm long not yet.
3. The condyloid canal is in elderembryo with vein visible, in younger one there is only a depression on the inner surface.
4. As for the ear capsule there is a difference of tissue character between the cochlear and the vestibular part in22mm longembryo; yet mesenchymal in the former, cartilageous in the latter part, while in35mm long both parts are completely cartilageous.
5. The facial canal which lies between these two parts is very short in the younger, a little longer in the elder, the facial groove on the outer surface of the capsule is shallow in the former, very deep in the latter.
6. The ear ossicles arecompletely cartilageous in 35 mm long embryo, in22mm long one the stapes is yet mesenchymal while malleus and incvs are already cartilageous.
7. The sella turcica is notyet visible in 22 mm long, while in 35mm long it is ashallow depression, the inclination of the clivus is already steep in the younger specimen, almost perpendicular in the elder.
8. Ala temporalis is completely cartilageous in 35 mm long embryo, while in22mm long the ventral half surrounding n. maxillaris is yet mesenchymal.Thecartilageous proc. alicochlearis reaches ear capsule in the elder embryo, not yet in the younger.A.carotis int.with thick sympathetic nerves passes almost perpendicular medial to this process so that the canalis caroticus is completed in the elder.
9. Ala orbitalis is small in the younger, very large and fuse with nasal septum medially, with cartilago ethmosphenoidalis laterally. This medial fusion with septum nasi surrounds with alahypochiasmatica canalis fast.optici. The cartilageousnasal capsule is formed only in the elder emryo.(Department of Anatomy)

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