Dispersion patterns of clonally related cells during development of the hypothalamus.

To identify patterns of cell generation and migration during early development of the hypothalamus, clones were marked with a library of retroviral vectors. The majority of clones analyzed at Embryonic Days 8-10 were simple radial columns. A small number of clones had one of three unusual patterns of dispersion. One unusual clone type was bilaterally symmetric across the ventral forebrain. Another was composed of four or more columns of cells arranged in a line along the ventricular surface, and a third was composed of cells that appeared to disperse from the typical radial columns in a plane parallel to the ventricular surface. The appearance of the rare clones suggests that there are different mechanisms of clonal dispersion during early development of the ventral forebrain that could play a role in patterning the hypothalamus.