MEDIAN SAGITTAL DISSECTIONS 



151 



the fourth ventricle, which is now spread out laterally and flattened dorso-ven- 

 trally. About the notochord mesenchymal anlages which form the centra of the 

 vertebra; are prominent. 



Turning to the alimentary tract, observe that the primitive mouth cavity 



Pi'dunc. cerebri 



Epiphysis Thalamus 

 Mesencephalon 



Tela chorioidea 



Cerebellum 



X 



Chorioidal plexus ventricle 4 



Tela of ventricle 4 

 Myelencephalon 



Lai. chorioid plexus 



Corpus striatum 



Hypophysis 

 Lobus olfactorius 

 Turbinate anlage 



Palate 



Pulmonary artery 



Gall bladder 

 Small intestine 



Urogenital sinus with mesonephric duct Rectum 



Fig. 142. — Median sagittal dissection of a 35 mm. embryo. 



is now divided by the palatine folds into the upper nasal passages and lower 

 oral cavity. In the lateral walls of the nasal passages develop the anlages of the 

 turbinate bones. On the floor of the mouth and pharynx, the tongue and epiglottis 

 become more prominent. The trachea and esophagus elongate and the lungs lie 



