144 



THE DISSECTION OF PIG EMBRYOS 



Turning to the alimentary tract, observe that the primitive mouth cavity 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 tmbinate 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 more and more caudad. The dorsal portion of 



Epiphysis 

 Mesencephalon 



Pedunculus cerebri 



Cerebellum 

 Chorioidal plexus, ventricle 4 



Tela of ventricle 4 

 Myelencephalon- 



Epi glottis. 



Esophagus 

 Spinal cord 

 Trachea 



Aorta 

 R. atrium 

 R. bronchus 

 Dorsal aorta 

 Inf. vena coaia 

 Stomach 

 Pancreas 

 Suprarenal gland 

 Genital gland 

 Duodenum 



Melanephros 



Colon 

 L. mesonephric duct 



Thalamus 



Tela chorioidea 



Lat. chorioid plexus 



Corpus striatum 



Hypophysis 

 Lobus olfactorius 

 Turbinaie anlage 



Palate 

 Tongue 



Pulmonary artery 



Ventricle 



Diaphragm 



Liver 



Caecum 



Gall bladder 

 Small intestine 



Urethra 



'Bladder 

 'Anus 



Ureter 



Urogenital sinus -with mesonephric duct Rectum 



FIG. 147. Median sagittal dissection of a 35 mm. embryo. 



X4- 



the septum transversum, the anlage of a portion of the diaphragm, is thus carried caudad, 

 and although originally, when traced from the dorsal body wall, it was directed caudad and 

 ventrad, now it curves cephalad and ventrad, bulging cephalad into the thorax. The 

 proximal limb of the intestinal loop elongates rapidly, and, beginning with the duodenum, 

 becomes flexed and coiled in a characteristic manner. The distal limb of the intestinal 



