I.Lr.S. 



394 THE PINEAL ORGAN 



5 years of age stained by the ordinary harmatoxylin and eosin method. 

 We shall then endeavour to interpret the appearances seen at this stage 

 of development and in the organ of adult individuals by a reference to 

 the earlier stages of embryonic and foetal development and by the micro- 

 scopic pictures brought out by the use of differential stains. The pineal 

 organ at this stage is invested by a fibrovascular capsule, derived from 

 the pia mater and lined internally by a glial stratum. This capsule sends 

 trabecular containing blood-vessels into the substance of the gland. The 

 trabecular pass inwards and partially surround the peripheral part of a 



branched system of 

 lobules which pri- 

 marily originate from 

 the ependymal epithe- 

 lium of the embryonic 

 pineal diverticulum. 

 The epithelial tissue 

 of the lobules is, how- 

 ever, penetrated 

 throughout by fine 

 trabecular of intra- 

 lobular connective 

 tissue containing ca- 

 pillary blood-vessels. 

 The lobular areas be- 

 tween the larger trabe- 

 Fig. 264. — Tangential Section of the Pineal Gland cu ]^ which grow in- 

 of a Child, showing the Fibrous Capsule, Lobes, , - *" , , 



and Interlobar Septa. (R. J. G.) ward from the capsule 



Ca. : capsule. communicate with 



I.L.S. : interlobular septum. eac h ot her i n the 



I.Lr. S. : intralobular septum. , ,, , 



P. : parenchyma. central part of the 



gland so that the 

 lobules as a rule are not completely enclosed in separate compart- 

 ments, but are continuous with a central mass of parenchymatous tissue 

 which is more uniform in appearance than the lobulated peripheral zone. 

 The lobules consist of a supporting glial tissue which has the character of 

 a fibrillated sponge-work or reticulum enclosing clear intercommunicat- 

 ing spaces. Some of the spaces contain parenchyma cells with vesicular 

 nuclei, while others appear empty. The reticulum is especially noticeable 

 beneath the capsule and in relation with the larger trabecular. The cell- 

 elements of the reticulum have the appearance of being continuous with 

 each other, no intercellular septa or intervals ever being visible with the 

 ordinary methods of preparation. The network thus seems to be formed 



J-Pa. 



