The Collaborative International Dictionary of English v.0.48:

Leucocytogenesis \Leu`co*cy`to*gen"e*sis\
   (-s[imac]`t[-o]*j[e^]n"[-e]*s[i^]s), n. [Leucocyte +
   genesis.] (Physiol.)
   The formation of leucocytes.
   [1913 Webster]