A biological cell labeling technique and its use in expermental embryology

A cell-labeling technique is proposed, based on structural differences between the interphase nucleus of two species of birds, the japanese quail (Coturnix coturnix japonica) and the chick (Gallus gallus). The quail nucleus shows large heterochromatic masses associated with the nucleolar RNA. In the chick, on the contrary, the arrangement of chromatin during the interphase fits the general pattern observed in vertebrate cells: DNA is rather uniformly distributed in the nucleoplasm, and the quantity of nucleolus-associated chromatin is not significant. It is possible to distinguish the cells of the two species in histological sections stained by the Feulgen Rossenbeck reaction, and also at the electron microscope level in sections involving the nucleolus. Thus quail cells can be used as “natural markers” to study various embryological problems such as those related to intercellular interactions and cell migration during ontogeny.