140 



THE DISSECTION OF PIG EMBRYOS 



off any surplus celloidin, mount embryo in desired position and immerse watch glass in 

 80 per cent alcohol, in which the specimen may be kept indefinitely. Embryos may also 

 be mounted in gelatin-formalin solution in small, sealed glass jars. 



Lateral Dissections of the Viscera. Dissections like those shown in Figs. 144 and 

 145 may easily be prepared in less than an hour, and make valuable demonstration and 



Mesencephalon 

 Cerebellum \ 



Gang, geniculi n.7 

 Gang, acusticum n. 8 

 Gang, superius n. 9 

 Gang, accessorii 



Gang, jugulare n. 10 



Ga'iig. petrosum n. 



N. hypoglossus 



N. accessorius 

 Gang. cerv. 



Brachial pie. 



Lun, 



Diaphragm 

 Dorsal lobe of liver 



Mesonephros 

 Metaneph 



Nerve to lower limb 



Sciatic nerve 



FIG. 144. Lateral dissection of an 18 mm. pig embryo, showing the nervous system and 

 viscera from the right side. X 8. 



laboratory specimens. Skill is required to demonstrate most of the cerebral nerves, but the 

 central nervous system, cerebral and spinal ganglia, and viscera may easily be exposed. 

 Starting dorsally, make a sagittal section of the embryo slightly to one side of the median 

 line and avoiding the umbilical cord ventrally. With the embryo resting on the flat, sec- 

 tioned surface, begin at the cervical flexure, and with fine forceps grasp the ectoderm and 

 dural anlage at its cut edge, separate it from the neural tube and pia mater, and strip it 



N. oculomotorius 

 I N. trochlearis 



Gang, semilunare n. 5 



Mandibular ramus n. 5 

 ^/Ophthalmic ramus n. 5 

 N. opticus 



Cerebrum 



Maxillary ramus n. 5 

 Chorda tympani n. 7 

 N. facialis 



Gang, nodosum n. iO 



R. atrium ' 

 R. ventricle 



Ventral lobe of liver 



Umbilical cord 



