Golgi orientation and cell behaviour in the developing pattern of chondrogenic condensations in chick limb-bud mesenchyme.

Using a silver-impregnation method, the occurrence and significance of Golgi apparatus orientation has been studied in cells contributing to the cartilage condensations in the developing skeleton of the chick limb bud, both in normal embryos and in the talpid mutant, in which the pattern of condensation in situ, and cell behaviour in vitro, is abnormal. Analysis of photographed sections made up as photomontages with a final magnification of X 1000, indicates a sequence of changing Golgi orientation in the course of establishing cartilage condensations in the mesenchyme in normal limb buds, including at an early stage an orientation of one population of cells towards the condensation centre and of another population in the contrary direction, and a modification of the sequence in the mutant. The changing patterns of cell orientation has been further analysed in scanning electron microscope studies on the formation of cartilage condensations in vitro.