[BS] Q.12) Development of RBC:

Ans.

 A. Embryonic life:

a. 1^st Trimester – From mesoderm of yolk sac

b. 2^nd Trimester – from liver (mainly), spleen, lymph node

c. 3^rd Trimester – from bone marrow.

B. Extra Embryonic life:

a. Up to 20 years from long bones marrow.

b. Beyond 20 years from all membranous bone.