Question
Explain the development of dicot embryo.
✓
Answer
Development of embryo (dicot) in angio- sperm:
The oospore undergoes a transverse division to form a large basal cell towards the micropyle and a small apical or terminal cell towards the chalaza of the embryo sac. This two celled structure is called proembryo. The basal cell or suspensor initial undergoes repeated transverse divisions to form a multicellular structure called suspensor. The suspensor pushes the embryo towards the endosperm to draw its nutrition.
- The development of embryo from a zygote is called embryogenesis.
- The fusion of male gamete and an egg cell during fertilization results in the formation of a diploid zygote. The zygote develops a wall around it and is converted into oospore.
- The apical cell or embryonal initial of the proembryo undergoes a transverse division followed by two vertical divisions at right angles to form an octant stage.
- From octant, the lower four cells form hypocotyl and radicle while four cells of upper side form plumule with two cotyledons.
- The lowermost cell of suspensor is hypophysis and by its further division forms part of radicle and root cap.
- The cells from upper side of octant divide repeatedly to form heart shaped which elongated further to form two lateral cotyledons.
- Enlargement of hypocotyl and cotyledon results into curved embryo which appears horse shoe shaped.
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Stem cells hold the potential for manifold applications in biotechnology based next generation therapeutics. Scientists are trying to formulate better and more personalised treatment modalities against some seemingly irremediable diseases, by harnessing body's own stem cells and stem cell niche. Stem cells of different origin and level of potency are being investigated for tissue regeneration, treatment of bone defect, drug testing, gene therapy and cell based therapy for muscle damage, spinal cord injury, cancer therapy, etc. 'Tile properties of embryonic and adult stem cells to either self-renew or differentiate into multiple cell lineages make them an attractive source for cell therapies, tissue engineering and as model system for drug screening.
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