Correct developmental sequence of somatic embryos is:
Correct developmental sequence of somatic embryos mirrors zygotic embryogenesis ordered phases globular heart torpedo cotyledonary reflecting progressive establishment of apical basal and radial patterning. Initially small cluster of embryogenic cells organizes into globular stage spherical mass with protoderm outer layer and no vascular differentiation representing early embryogenesis governed by WOX2 WOX8 expression. Transition to heart stage involves emergence of bilateral symmetry with two cotyledonary primordia flanking shoot apical meristem central dome and root pole opposite, driven by auxin maxima at cotyledon tips through PIN1 PIN7 transport. Elongation of embryonic axis produces torpedo stage where hypocotyl elongates root meristem with quiescent center defined by WOX5 PLETHORA gradients becomes distinct and cotyledons elongate. Final cotyledonary stage shows expanded cotyledons filled with storage proteins lipids starch accumulating LEA proteins for desiccation tolerance and chlorophyll differentiation for photosynthetic competence. Monocots analogous stages are globular scutellar coleoptilar. Maintaining this sequence through hormone withdrawal ensures functional shoot root poles and high conversion frequency into plantlets upon germination medium.
Ref: Zimmerman 1993; Taiz & Zeiger Chap. 16 embryogenesis stages globular heart torpedo.