562 APPENDIX 



oil immersion. The proportion of cells with a reticulum (deep blue) in a sample of at 

 least 500 erythrocytes (pale blue-green) is determined. Use of a Whipple ocular 

 micrometer disk marked in a 100-square grid greatly facilitates counting. 



Leucocyte counts. — It is frequently desirable in connection with analysis of anemic 

 states to have information on levels of leucocytes and other nucleated cells. Total 

 leucocyte counts can be carried out in mice using the Neubauer chamber, regulation 

 human white-counting pipettes, and gentian-violet-stained 3 per cent acetic acid 

 diluent. The proportion of granulocytes is much higher in mouse than in man, 

 varying from a mean of 74 per cent to a mean of 92 per cent among 1 8 tested inbred 

 strains. 1108 Separate direct chamber counts of granulocytes and agranulocytes can 

 be obtained by the Randolph method using propylene-glycol diluent. 141 - 1260 For 

 many purposes differential smear counts are very satisfactory, and special modifications 

 of staining methods have been developed for use with blood of mice. 1261 



Study of hematopoietic tissues. — Total cellularity of marrow of the mouse may be 

 calculated from the proportion of available marrow space occupied by hematopoietic 

 cells. 324 - 1110 A Whipple, ocular-micrometer disk marked in a 100-square grid facili- 

 tates classification, which may be made at 430 x or 970 x magnification, or preferably 

 at both. Proportional counts of types of hematopoietic cells may be made from touch 

 imprints or smears stained with Wright-Giemsa. 125 - 1110 Because differences in staining 

 properties of mouse and human marrow cells make it difficult to classify murine marrow 

 from the appearance of the cytoplasm, the nucleus only is used in classifying members 

 of the erythropoietic series. 125 These methods for classifying marrow histology may be 

 applied to all postnatal stages. 



