Development of embryo (dicot) in angiosperm :
(1) The development of embrlyo from a zygote is called embryogensis .
(2) The fusion of male gamete and an egg cell during fertilization results in the formation of a diploid zygote.
(3) The zygote develops a wall around it and is converted into oospore.
(4) The oospore undergoes a transverse division to from a large basal cell towards the microphyle and a small apical cell towards the interior of the embryo sac. This two celled structure is called proembryo.
(5) The basal cell undergoes repeated transverse divisions to form a multicellular structure called suspensor.
(6) The suspensor pushes the embryo towards the endosperm to draw its nutrition .
(7) The apical cell of the proembryo undergoes a transverse division followed by two vertical divisions at right angles to form an octant stage.
(8) The cells of actant now undergo an unequal periclinal division to form an outer layer of eitht smaller cells and an inner layer or eight larger cells.
(9) The cells of the outer layer give rise to the dermatogen. The dermatogen in turn gives rise to the epidermis.
(10) The cells of the inner layer gives rise to an embryonal mass which on differentiation form procambium and ground meristem.
(11) The procambium and ground meristem undergo differentiation and form an embryonal axis consisting of a plumule, a radical and two cotyledons.
