TRANSVERSE SECTIONS OF A TEN MM. PIG EMBRYO 



129 



more cephalad in the series. Ventral to the otocyst are seen the geniculate and acoustic 

 ganglia of the nn. facialis and acusticus. The wall of the otocyst forms a sharply denned 

 epithelial layer. More cephalad in the series the endolymph duct lies median to the oto- 

 cyst and connects with it. Dorsal to the otocyst the n. glossopharyngeus and the jugular 

 ganglion of the vagus are cut transversely while the trunk of the n. accessorius is cut length- 

 wise. 



Section through the First and Second Pharyngeal Pouches (Fig. 130). The end of 

 the head, with sections of the telencephalon and of the ends of the olfactory pits, is now 



N. accessorius 



Gang. Froriep 



Myelencephalon 



Basilar artery 

 Notochord 



Neural cavity 



Gang, petrosum n. g 

 Pharyngeal pouch 2 



Pharyngeal pouch i 

 Oral cavity 



Olfactory pit 



Roots of n. hypoglossus 



Int. jugular vein 



Nn.vagus el accessorius 

 Descending aorta 



N. facialis 

 Branchial arch 2 

 Tongue 

 Mandible 



Maxillary process 





Telencephalon 



FIG. 130. Transverse section through the first and second pharyngeal pouches of a 10 mm. pig 



embryo. X 22.5. 



distinct] from the rest of the "section. The pharynx shows portions of the first and 

 second pharyngeal pouches. Opposite the first pouch externally is the first branchial 

 groove. A section of the tuberculum impar of the tongue shows near the midplane in the 

 pharyngeal cavity. The neural tube is sectioned dorsally at the level of Froriep 's ganglion. 

 Between the neural tube and the pharynx may be seen on each side the several root fascicles 

 of the n. hypoglossus, the fibers of the nn. vagus and accessorius, and the petrosal ganglion 

 of the n. glossopharyngeus. Mesial to the ganglia are the descending aorta and lateral to 

 the vagus is the internal jugular vein. 



