Embryo, heart shaped torpedo stage

On the other hand, inhibitors such as ABA (abscisic acid) are used in the further stages of somatic embryogenesis. They cause the maturation of somatic embryos through globular, heart-shaped, torpedo and cotyledonary stages (Fig. 1), and in the final stage -their development into the seedling. Moreover, ABA increases the resistance of cells to stress conditions. 

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