NERVE SUPPLY OF PINEAL SYSTEM OF SPHENODON 26l 



between the pineal sac and the posterior wall of the dorsal sac. Dendy 

 was unable to follow individual fibres continuously to the habenular region, 



Fig. 185. 

 (After Dendy, 19 11.) 



-Transverse section through the lower part of the tractus pinealis, and the 

 habenular ganglia of an adult Sphenodon ; note the cavity in the pineal sac, 

 with an ependymal groove in its floor. B — Transverse section through the 

 same specimen as A at the junction of the tractus pinealis with the brain, 

 showing the recessus pinealis, the subcommissural organ, and the fasciculus 

 retroflexus of Meynert. C — Longitudinal vertical section through the pineal 

 region of an adult Sphenodon, showing a bundle of nerve-fibres N.P.E. 

 entering it from the posterior wall of the dorsal sac. D — Combined drawing 

 from several sections of the same series as the preceding, showing the lower 

 end of the tractus pinealis, the posterior, and the habenular commissures 

 and the subcommissural organ. 



blood-vessel. 



habenular commissure. 



posterior commissure. 



: cavity of pineal sac. 



: fasciculus-retroflexus of Mey- 



B.V. : 

 C.H. : 

 C.P. : 

 C.P.S. 



FR.M. 



nert. 

 G.H.M., G.H.D., G.H.S., ganglion 



habenulse medjus — dexter — sinistra?. 

 N.P.E. : nerve of parietal eye. 

 P.M. : pia mater. 



but he found that numerous fibres entered the left habenular ganglion 

 from the wall of the dorsal sac. Fibres from the same area were also 



P.S. : pineal sac. 



R.N. : cells of roof nuclei. 



R.P. : recessus pinealis (" infra-pineal 



recess ")• 

 SCO. : subcommissural organ. 

 T.P. : tractus pinealis. 

 V.P.S. : vessel of pineal sac. 

 K.3. : third ventricle. 

 W.D.S. : wall of dorsal sac. 



