size of ferritin particles

[FRANCISCO J HERNANDEZ BLAZQUEZ fzea - zab 0195 616122 - 283]

I'm workin with ferritin from horse spleen (Sigma I) as an
electron microscopic marker. Although it is easy to identify the
 particles in the micrographs, I would like to know the exact
size of theses particles. Could you help me, please
Thank you
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Francisco Javier Hernandez Blazquez        |        
Universidade de Sao Paulo - Faculdade de   | e-mail fjhblazq at usp.br 
Zootecnia e Engenharia de Alimentos        | Voice: 55 195 616122 r. 265
Departamento de Ciencias Basicas/Histologia|                      r. 278
Av. Duque de Caxias Norte, 225    CP 23    | Fax:   55 195 611689
CEP 13630-000 Pirassununga (Sao Paulo)     | 	    55 11 8694831 
BRAZIL 	                                   |
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