TRANSPARENT CHAMBER 

 TECHNIQUE 



352 



TRANSPARENT CHAMBER 

 TECHNIQUE 



outer rim of both the base and the top 

 ring, large enough to take bolts 0.040" 

 in diameter. The chamber fits the ear 

 best if trinmied to a pear shape. The 

 edges of both base and top are rounded. 

 To the table, close to its outer rim, are 

 glued 4 "buffers" (or separators) — 

 squares or octagons of celluloid, 5 mm. 

 wide and either 42 or 75 micra thick, 

 depending upon the thickness of grow- 

 ing space desired. The purpose of the 

 "buffers" is to leave a non-compressible 

 open space, into which tissues may grow 

 when the top of the chamber is bolted 

 to the base. The bolts are of brass, 

 and may be either headed (1 cm. long) 

 or headless (1.5 cm. long). They are 

 made from brass wire 0.040" (1.0 mm.) 

 in diameter, threaded 120 turns to the 

 inch (47 to the cm.). The brass nuts 

 are he.xagonal. The central 3 mm. of 

 the bolts is coated with celluloid by 

 dipping in celluloid dissolved in equal 

 parts of absolute alcohol and ether 

 and removing the celluloid from the 

 end sections. 



Rabbits used for installation of ear 

 chambers should have ears at least 5 

 inches long, should be free from "snuf- 

 fles" and from "ear-mite, and should 

 have no scars in the chamber region. 

 The chamber is inserted in the ear at 

 a place about two-thirds of the distance 

 from base to tip, in the flat portion be- 

 low the central artery and nerve, with 

 the round-table close to the central 

 artery. With a nearly-sharp, heart- 

 shaped dissector, the skin is raised on 

 both sides of the ear, over an area about 

 two mm. beyond the limits of the 

 chamber — care being taken to remove 

 all the dermis, but to leave the vascular 

 subcutaneous layer behind. The cen- 

 tral portion of the raised skin is re- 

 moved to a distance about 4 mm. from 

 the outer edge. A round hole is cut 

 clear through the ear, slightly larger 

 than the top of the table, and the base 

 of the table is placed in position with 

 the table projecting through the hole. 

 The three bolts are forced through the 

 ear following a needle and the end of a 

 probe, the table top is brought down 

 over the three bolts, and the loosened 

 skin is lifted up over the edges of the 

 table on both surfaces of the ear. The 

 nuts are screwed down on the bolts, 

 until the three buffers are clearly seen, 

 but not enough to cause the mica to 

 bulge. The splints and shields (Clark, 

 E. R. and E. L. Clark, Anat. Rec, 

 1932, 51, 55) — the former a flat ring of 

 .66 mm. thick celluloid, the latter a 

 pie-plate shaped piece of 0.24 mm. thick 

 celluloid, shaped by heating in a 

 mould — are installed as follows. Two 



holes are made in the ear with a leather 

 punch. Through each hole is passed a 

 headless bolt outside of which is a glass 

 sleeve about 4 mm. long. This sleeve 

 protects the ear from the bolt. The 

 hole in the outer splint is large enough 

 so that the splint clears the chamber. 

 The inner splint is trimmed down to a 

 half ring, to fit the ear fold, and the 

 edge rounded. Bits of sterile gauze are 

 pushed into the space around the 

 sleeves. The operations are performed 

 under strict asepsis-aqueous solution 

 of metaphen, 1:500, being the disin- 

 fectant of choice, both for preparing 

 the ear and for sterilizing the chambers. 

 Local anesthesia is used — injections of 

 novocaine, 2%, being made across the 

 base of the ear. 



Microscopic observations are made 

 with the rabbit lying on its back, held 

 by a special rabbit board (E. R. Clark, 

 Sandison and Hou, Anat. Rec, 1931, 

 50, 169), while the ear is clamped to a 

 wooden or bakelite holder, which is 

 held and moved about by the mechan- 

 ical stage. Camera ludida drawings 

 are made using the Leitz "Zeichen- 

 ocular #4", which allows the micro- 

 scope to be tilted at an angle of 45 

 degrees. The microscope rests on a 

 sheet of heavy plate-glass which is 

 raised at the sides sufficiently to permit 

 a drawing board to move underneath. 

 Illumination is provided by a 6-volt 

 concentrated or ribbon filament lamp, 

 the light passing through water filter 

 or heat-resisting glass. Photographs 

 of whole chamber are made with a 

 bellows camera, using 16 or 32 mm. 

 lenses; photomicrographs with the 

 Leitz "Leica," or similar type camera, 

 that concentrate the light, permitting 

 oil immersion pictures of ^q" to -^■^" ex- 

 posure; and motion pictures including 

 'time-lapse" motion pictures. While 

 oil immersion studies may be made, 

 a most useful lens is the 8 mm., 20X 

 apochromatic objective long working- 

 distance type with small-tipped nose- 

 piece), since e.xcellent resolution is 

 obtained with even a 25X compensat- 

 ing ocular. Since the object is about 

 1 cm. above the top of the microscope 

 stage, illumination is improved by 

 either removing the top lens of the 

 condensor, or by using a supplementary 

 lens placed between the regular con- 

 densor and the mirror — as designed by 

 Dr. Poser, for Bausch and Lomb, which 

 sends a beam of parallel rays, instead 

 of rays converging at the thickness of 

 a glass slide and then diverging. 



A second type of chamber has been 

 named the "preformed tissue" chamber 

 (E. R. Clark, Kirby-Smith, Rex and 



