Figs. 21–29. Light micrographs illustrating stages of embryo development. All sections longitudinal and oriented with chalazal end toward top of page. Scale bars in Figs. 21–26 = 10 µm; in Figs. 27–29 = 30 µm. 21. Zygote that has begun to elongate toward the endosperm. 22. Two-celled proembryo with large and highly vacuolate basal cell and smaller apical cell. 23. Four-celled, linear proembryo. 24. Six-celled, linear proembryo. 25. Initiation of embryo proper. 26. Later globular proembryo with four-celled suspensor. 27. Early stages of organogenesis; suspensor still present. 28. Early axial embryo with developing radical and cotyledons and clearly visible primary meristematic tissue zones, still attached to suspensor. 29. Embryo that was displaced from the micropylar end and is developing in the middle with endosperm that has cellularized around it. Scale bar = 100 µm