What kind of morphologically recognizable haemopoietic cells do we inject when doing foetal liver infusion in man?

Abstract

There is no agreement, how to define the age of the embryo/foetus. From the 15th (fertilization) week onwards the whole foetal liver contains some 10(9) free haemopoietic cells. Before, and up to the 30th-34th weeks, the liver is the main site of haemopoiesis. The differential of embryonic smears (up to wk 9) differs from that of foetal ones. The first invasion of circulating primitive erythroblasts seeding in the liver (early 5th wk) is accompanied by the appearance of a lot of sinusoidal macrophages. Definitive erythropoiesis expands during the 6th-7th wks. Granulocytic representation peaks at 15-16 wks. Megakaryocytes are small and have few nuclei/nuclear lobes. Five to 8, or even more per cent of single haemopoietic cells were lymphoid-like cells in the 5th-6th wk liver smear. These cells precede the development of any lymphoid structure in the foetus. Ordinary lymphocytes amount to less than 2% between 10 and 18 wks, and reached 3% at wk 24. Percentage of dyserythropoietic nuclei in smears has been used to decide whether the injected cells could be regarded as 'physiological' cells. Ten out of 11 apparently healthy foetuses, delivered by hysterectomy/hysterotomy for maternal interest, aged 10 1/2 to 20 1/2 weeks, had mean 4.5% liver dyserythropoiesis. Extremely high dyserythropoiesis was associated with multilineage, instead of overwhelmingly erythroid haemopoiesis.