erythrogonium

e·ryth·ro·go·ni·um

, pl.

e·ryth·ro·go·ni·a

(ĕ-rith'rō-gō'nē-ŭm, -nē-ă), The precursor of an erythrocyte; occasionally refers to the erythropoietic tissue as a whole. [erythro- + G. gonē, generation]

erythrogonium

(1) Burst-forming unit-erythroid, see there.
(2) Erythroid stem cell, see there. 
(3) Erythron, see there.