Embryonic tissues were dissected and cells were cultured under osteogenic,adipogenic and chondrogenic conditions as described in the Materials and methods.

+, capacity of differentiation into the specific lineage.

−, lack of potential to differentiate into the specific lineage.

From the tissue remnants remaining after the dissection of the YS, head,somites, limb buds, heart, liver, vitelline and umbilical arteries, and the AGM region, we occasionally found some limiting osteogenic and chondrogenic activity. Thusfar, we have not been able to identify the specific cells responsible for the activity.

YS, yolk sac; AGM, aorta-gonad-mesonephros.

Attributable to the presence of an already differentiated prechondrogenic mass.