10 EXPERIMENTAL EQUIPMENT AND PROCEDURES 



the glass bubble down to the wall of the pipette and smooth oil the edges in a n:ncro- 

 burner. With diamond point cut off the closed tip of the capillary end so that the 

 aperture will be about 1 mm. in diameter. Cut a short piece of thin-walled rubber 

 tubing and slip it (from larger end) over the pipette to the point where it covers the 



RUBBER TUBING OVER 

 SIDE HOLE 



SPEMANN MICROPIPETTE FOR TRANSPLANTATIONS 



lateral hole. Heat the broad end of the pipette until very soft, press down on metal 

 surface to give a ridge to hold the rubber nipple. Add rubber nipple to this end, and 

 the pipette is ready for use. (See illustrations above). 



This latter pipette is of special value in the transfer of small pieces of tissue under 

 solution. With nipple, suck in solution until the capillary end is filled almost to the 

 lateral hole. Remove fingers from nipple and place a forefinger over the rubber- 

 covered lateral hole. With the capillary point under the solution, force out a small 

 amount of the contents of the pipette by gently pressing on the lateral rubber cover 

 with the forefinger. Then, by releasing the gentle pressure a small amount of fluid, 

 or tissue, may be drawn up into the pipette and held there. This tissue may be 

 oriented at any place by slight pressure on this lateral membrane. The capillary end 

 must hold solution (not drip) even when held vertically with the point suspended. 

 Practice the use of this pipette with small objects. 



Glass bridges : These are small pieces of cover glass, thinnest grade, used to hold 

 transplanted tissues in place for 15+ minutes while they "take" or heal onto the host. 

 Using a diamond point pencil and ruler, cut thin cover glasses into strips of about 

 2-3 mm. wide and 5-10 mm. long. With forceps run the edges of these glass strips 

 through a micro-flame to make them smooth. To put a slight curve in some of the 

 pieces of cover glass, grasp the edge of a piece with forceps and bring the center of 

 it over a micro-burner with a 1 mm. flame. The weight of the cold end will bend the 

 cover slip slightly when the center is heated. The height of the bridge should be de- 

 termined by the size of the embryo to be used as host. Frequently flat cover slips 

 will prove to be adequate, especially when the host is held in a depression. The 

 bridges should be sterilized in 70% alcohol over cotton and kept thus in a covered 

 slender dish. 



There is a refinement of this type of bridge (or Brucke) described by Schultze, (1938). 

 The cover itself consists of transparent Pyralin of less than 2 mm. thickness cut 

 into rectangular blocks of 1/8 inch by 3/8 inches each. Holes are drilled through 

 each end of the block with #70 or #71 wire gauge drill. The edges of the block are 

 smoothed off with fine file and then dipped in very weak balsam to increase trans- 

 parency. Take care that balsam does not fill the holes. Small safety pins, (prefer- 

 ably gold plated to prevent rusting) are straightened out and then given three right 

 angle bends as shown in the diagram. The pins are then forced through the holes, to 

 the extent of 5-6 mm. Such a graft cover may be pressed down onto the graft exactly 

 as desired, the pins anchored in the Permoplast and the Pyralin allowing constant 

 observation of the graft. In most transplantations such an elaborate Brucke is not 

 necessary. 



