Later Development, Develop. Physiol., Dr. D. Penney

Table 3.08 - Hematopoiesis - Sites of Blood Formation during Development in Chronological Order of Appearance.

• Yolk sac - 4th week; ends 2nd mo.

• Body mesenchyme and blood vessels - 5th week

• Liver - 6th week; ends at birth

• Spleen, thymus and lymph glands - and - 4th mo.

• Bone marrow - 4th mo.; dominant by 5th mo.

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