Zygotic embryo development in Daucus carota

After fertilization, the zygote divided unequally, giving rise to a larger basal cell and a smaller terminal cell. Derivatives from the basal cell gave rise to the suspensor and the terminal cell gave rise to the embryo proper. The suspensor usually consisted of a uniseriate file of 10-12 cells. However, additional anticlinal and oblique divisions resulted in some suspensors having more than one cell file. Cuticular substance was not present in the suspensor cell wall. The embryo proper was derived from the terminal four cells of the eight-celled embryo. The protoderm differentiated first, and subsequent to its formation cuticular substance could be detected in the outer tangential walls using the Nile red stain. This staining pattern intensified as the embryo matured. A defined cell lineage was not associated with tissue and meristem differentiation. Meristems began to form at the heart stage and became clearly defined at the late heart - early cotyledon stage.