Table 1. Fetal Hematopoiesis SITES TIME PRODUC Mesoblastic Yolk Sac 10-14th day Erythroid hematopoisis 3-4wk: primitive blasts 10-12wk ceased e Hepatic Liver 6-8wk appear Erythroid hematopoiesis 12-16wk. active 6mo: diminish/ stop at birth e Myeloid B one 4mo start Erythroid e hematopoiesis marrow 6mo: increase/steady Neutrophils after birth: the only MacrophagesSITES TIME PRODUC Measoblastic hematopoisis Yolk Sac 10-14th day 3-4wk:primitive blasts 10-12wk:ceased Erythroid Hepatic hematopoiesis Liver 6-8wk:appear 12-16wk:active 6mo:diminish/ stop at birth Erythroid Myeloid hematopoiesis Bone marrow 4mo:start 6mo:increase/steady after birth: the only Erythroid Neutrophils Macrophages Table 1. Fetal Hematopoiesis