TECHNIQUES FOR THE STUDY OF ANEMIAS IN MICE 559 



collections represent a considerable drain upon the erythron. The blood of mice 

 clots exceedingly rapidly, and use of an anticoagulant, either by addition of 1 per cent 

 heparin solution to the blood sample or by collection in dried heparinized or oxalated 

 tubes, is very important. 



For some experiments, the purpose is simply to obtain large quantities of blood 

 or serum. A large volume (more than 1 ml.) of blood may be collected (with sacrifice 

 of the donor on a dissecting board, under Nembutal) by allowing blood to flow from the 

 severed brachial artery into a pocket prepared in the brachial plexus. Large quantities 

 may also be obtained by cutting a mouse across the thorax through the heart and allow- 

 ing blood to flow into a collecting tube. 



Experienced operators use cardiac puncture to obtain as much as 0.6-0.8 ml. of 

 blood from either ventricle (that is, separate samples of arterial or venous blood) 

 of adult mice without sacrifice of the donor. 1374 ' 1398 A description of the procedure 

 by H. G. Wolfe follows: For this purpose a 0.5- or 1.0-ml. syringe and no. 26 or 27 

 needle is used. A ring stand or other suitable device is used for attaching a short 

 length of cord with a loop in the end through which the head of the plunger of the 

 syringe is passed. The loop must be large enough so that the head of the plunger 

 can be disengaged and yet snug enough so that it can be used to retract the plunger 

 during the operation. The needle and syringe may be rinsed in an anticoagulant 

 solution, or, if desired, no anticoagulant need be used if the blood is delivered immediate- 

 ly into a receptacle either with or without an anticoagulant in it, depending upon the 

 particular experiment. The nonanesthetized mouse is held firmly in one hand with its 

 ventral surface up. The ventral thorax should be disinfected with a germicide such 

 as 70 per cent ethyl alcohol. This at the same time flattens the hair and enables the 

 technician to see the exact outlines of the rib cage. A sterile needle from the mounted 

 syringe is inserted through the rib cage near the xiphisternum and slightly to the left 

 of it; the exact point of insertion must necessarily be determined empirically by practice 

 and preference on the part of the technician. When the needle penetrates either the 

 right or left ventricle, the mouse and syringe are simultaneously and gently moved 

 away from the restrained plunger. One can always tell if the needle is properly inserted 

 by the sudden lack of resistance between syringe and plunger. With practice and by 

 simply altering the angle of penetration one can extract either arterial or venous blood 

 from the left and right ventricles respectively, with a fair degree of accuracy. The 

 blood can be drawn quite rapidly; the complete operation takes from 1 to 2 minutes 

 once the equipment is properly set up. Age and size of the mouse are factors 

 determining the amount of blood which can be drawn. 



Collection of peripheral blood for quantitative evaluation. — When blood samples are 

 taken for the purpose of characterizing the blood picture of the host, one of three general 

 methods is commonly used. Blood may be collected from a slash in the lateral tail 

 vein, especially if the whole animal has been warmed in a glass jar placed under a 

 lamp or if the tail has been placed in hot water immediately before sample collection. 

 Care must be taken not to massage the tail, as this often leads to erroneous counts. 



