A STUDY OF THE CHOROID PLEXUS. 



BY 



WALTER J. MEEK. 



(From the Neurological Laboratory of the University of Chicago.) 

 With Nine Figures. 



With the exception of scant references in the standard anat- 

 omies, very Httle Hterature treating of the choroid plexuses is 

 available to the general student. The literature dealing with the 

 subject directly is not as full as one might wish, and in fact many 

 questions of interest concerning these structures still remain 

 unanswered. The object of the present paper is to review the 

 subject briefly to date, and to present some results of the author's 

 own investigations. 



The writer's attention was called to the choroid plexuses by 

 Dr. Shinkishi Hatai at the University of Chicago. Dr. Hatai 

 had noted that the position of the nucleus in the cells of the foetal 

 plexus was apical, while in the adult it was central. 



The problem as first undertaken was to determine the time of 

 this shifting of the nucleus, but as the work proceeded, it seemed 

 best to prepare a brief study of the entire subject. 



TECHNIQUE AND MATERIAL. 



Fixation of tissue is at best an unsatisfactory process, and 

 doubly so when structures as delicate as the choroid plexuses are 

 concerned. Slight differences of osmotic pressure cause shrinkage 

 or swelling of the cell. Mechanical injury must also be avoided. 

 The number of fixing fluids adapted to the plexuses is somewhat 

 limited. The following were used, and the order indicates approx- 

 limately their relative merit. 



Bouin's fluid. 



Carnoy's solution. 



Acetic sublimate. 



Potassium bichromate-corrosive sublimate solution. 



Kopsch's fluid. 



For small animals the best results were obtained by fixing the 

 entire brain. In the case of larger forms, the lateral ventricles 



