Template:Gilmour1941 table1
From Embryology
| Stage of development | Within embryo or extra-embryonic tissues | Within or outside vessels | Haemopoietic family | Type of erythropoiesls |
| Jones-Brewer presomite embryo till establishment of circulation (about 2.5 mm) | In blood islands in yolk sac, in some of cases in body stalk in the chorion or ' the embryo | Intravascular: possibly extravascular in body stalk in a few cases | Primitive | Megaloblastic |
| From establishment of circulation (about 2-5 mm.) to 9 mm. | In general circulation (of embryo, yolk sac and chorion) | Intravascular except for continued multiplication of cells in hemorrhages | Primitive | Megaloblastic |
| 10 mm. up to less than 48 mm. | In embryo, yolk sac and general circulation | Intra- and extra~vascular (marrow first in 57 mm. embryo) | Partly primitive, partly definitive in general circulation; definitive elsewhere | Megaloblastic |
| 48 mm to between 15 and 21 days after birth | Intracorporea1 in many organs and tissues | Extravascular, except sinuses of liver spleen and multiplication of cells in circulation (70 - 160 mm.) | Definitive | Partly megaloblastic, partly megalo-normoblastic (48-190 mm.); partly megaloblastic, partly normoblastic (190 mm. onwards) |
| 21 days or more after birth | Intracorporea1 in marrow only | Extravascular | Definitive | Normoblastic |
