LATERAL DISSECTIONS OF THE VISCERA 



147 



their change of position (Figs. 139 and 140). Compare the organs of 6, 10, 18 

 and 35 mm. embryos and note the rapid growth of the viscera (see Figs. 90 and 

 115). Hand-in-hand with the increased size of the viscera goes the diminution 

 of the dorsal and cervical flexures. In the brain, note the increased size of the 



Mesencephalon 

 Cerebellum 



Gang, geniculatum n. 7 



Gang, acust. n. 8 



Gang. sup. n. 9 

 Gang, accessor. 



N. oculomotorius 



N. trochlearis 



Gang, semilun. n. 5 



Gang, jugulare n. 10 



Gang, petrosal n. 9 

 N. hypoglossus 



N. accessorius 

 Gang. cerv. 



Brachial plexus 

 Lung 



Diaphragm 

 Dorsal lobe liver 



Mesonephros 

 Metanephros 



Nerve to lower limb 



Sciatic nerve 



FIG. 139. Lateral dissection of an 18 mm. pig embryo, showing the nervous system and viscera from 



the right side. X 15. 



cerebral hemispheres of the telencephalon and presence of the olfactory lobe of 

 the rhinencephalon. The cerebellum also becomes prominent and a ventral 

 flexure in the region of the pons, the pontine flexure, is more marked. The brain 

 grows relatively faster than the spinal cord and, by the elongation of their dorsal 



Mandibidar ramus n. 5 



Ophthalmic ramus n. 5 

 N. opticus 



Cerebrum 



Maxillary ramus n. 5 

 Chord, tymp. n. 7 

 'N. facialis 



'Gang, nodos. n. 10 



R. atrium 

 R. ventricle 



Ventral lobe liver 



Umbilical cord 



