STAINING, PRACTICAL AND THEORETICAL 



7. Infiltrate tissue blocks in the medium in a vacuum embed- 

 ding bath for one hour at 56° C; then transfer to a covered dish, 

 in the incubator at 56° C. for two hours per day for about seven 

 to ten days until the block has solidified. 



8. Trim and cut as in the case of celloidin blocks. 



ESTER WAX (i960), STANDARD 



(H. F. Steedman, ig6oa) 



Diethylene glycol distearate, neutral 300 gm. 

 Glyceryl monostearate . . . . 150 gm. 



Polyethylene glycol (300) distearate 50 gm. 



Melt the diethylene glycol distearate first and heat it until it 

 clears. Add the glyceryl monostearate, and when this is dissolved 

 add the remaining ingredient. Stir well while the mixture is 

 still hot, then filter through a ring of fine calico. 



Notes: 



The author (Steedman) states that this modification of his 

 earlier (1947) ester wax allows for variations in commercial 

 samples of stearate esters and produces an ester wax of physical 

 stability which gives consistent results. 



Ester wax (i960) melts at 48° C. and sections, flat, may be cut 

 from iju. to i2ja at temperatures between 17° and 27° C, and 

 ribbons may be obtained. 



The wax is soluble in absolute alcohol and 95% ethyl alcohol, 

 cellosolve, cedarwood oil, chloroform, xylol and a number of other 

 solvents both of the aliphatic and the aromatic series. Among the 

 clearing agents recommended are xylol, normal butyl alcohol and 

 absolute ethyl alcohol. 



A block measuring 20 x 10 x 10 mm. is ready for sectioning, at 

 a room temperature of 20° C, in about an hour after pouring. 

 Cutting speed recommended is 30 to 50 sections a minute. After 

 an appropriate length of time in the clearing agent the tissue 

 slices should be transferred to a bath consisting of approximately 

 equal parts of the wax and clearing agent. Time of infiltration in 

 the pure wax will depend, of course, on the size and nature of 

 the specimen, but a piece of liver about 4 to 5 mm. in thickness 

 will take about three hours with stirring, or about four hours 



504 



