Question

Arabidopsis embryogenesis hypophysis is observed in which stage

Answer 1

Plant embryogenesis is a process that occurs after the fertilization of an ovuleto produce a fully developed plant embryo. This is a pertinent stage in the plant life cycle that is followed by dormancy and germination.[1] The zygote produced after fertilization, must undergo various cellular divisions and differentiations to become a mature embryo.[1] An end stage embryo has five major components including the shoot apical meristem, hypocotyl, root meristem, root cap, and cotyledons.[1] Unlike animal embryogenesis, plant embryogenesis results in an immature form of the plant, lacking most structures like leaves, stems, and reproductive structures.

Embryogenesis occurs naturally as a result of single, or double fertilzation, of the ovule, giving rise to two distinct structures: the plant embryo and the endosperm which go on to develop into a seed.[3] 


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Answer 2

Stages of Arabidopsis embryogenesis. (A) Early embryo, with a single cell in the embryo proper. (B) Early embryo with 2 cells in the embryo proper. (C) Octant stage; four of eight cells in two tiers are visible. Cells of the upper and lower tier (u.t. and l.t.) of the octant will give rise to specifi c parts of the seedling (see Figure 1). Together with descendants of the uppermost suspensor cell (hypophyseal cell) the eight 'octant' cells will form all the structures of the seedling. (D) Dermatogen stage. A tangential division of each of the eight 'octant' cells produces inner cells and epidermis (protoderm) cells. (E) Early globular stage; divisions of the inner cells immediately after the dermatogen stage are oriented in the apical-basal dimension, endowing the embryo with a morphologically recognizable axis. (F) Triangular stage; now a polarized pattern of major elements is recognizable (see text): u.t. cells have generated two symmetrically positioned cotyledon primordia and l.t. cells a radially patterned cylinder (comprising epidermis, ground tissue and vascular tissue). Additional divisions distinguish the 'hypophyseal cell' from other suspensor cells. Its descendants will ultimately form the quiescent center of the primary root meristem and the columella initials. (G) Heart stage; cotyleldon outgrowth. Subsequently, cells between the outgrowing cotyledons initiate the primary shoot meristem. (H) Mid-torpedo stage; enlargement of cotyledons and hypocotyl and further elaboration of the radial pattern. (I) Bent cotyledon stage embryo with elaborated radial pattern in different organs. In the cotyledons a single adaxial subepidermal layer of elongated cells (palisade mesophyll) can be distinguished from underlying mesophyll cells. The radial pattern of the hypocotyl is comprised of a single cell layer of epidermal cells, two cortex layers, one endodermis and one pericycle layer enclosing the vascular cylinder. Bar is 5 μm in A, 10 μm in B, G and H, 15 μm in C and E, 20 μm in D and F, 50 μm in I.