Explants are pieces of tissue placed in culture. Callus is an unorganized mass of cells that forms from explants. There are three stages of callus culture: induction, proliferation, and differentiation. Cell suspension cultures can be initiated from callus and involve transferring callus pieces into liquid medium with agitation to break up cell aggregates. Organogenesis is the formation of organs like leaves and roots on explants, which can occur directly or indirectly through a callus stage. Somatic embryogenesis involves the formation of embryos from somatic cells and follows a similar development process to zygotic embryogenesis.

1. In Vitro Developmental Pathways

2. Explant - Piece of tissue put into culture -Tissue selection depends on purpose, species, many factors

7. Induction © 1998-2003, Branch of Shemyakin&Ovchinnikov IBCh RAS

8. Division E. Sutton, UC Davis

9. Callus © 1998-2003, Branch of Shemyakin&Ovchinnikov IBCh RAS

17. Growth Curve E. Sutton, UC Davis

30. Indirect organogenesis Explant -> Callus -> Meristemoid -> Primordium

32. © 1998-2003, Branch of Shemyakin&Ovchinnikov IBCh RAS

33. © 1998-2003, Branch of Shemyakin&Ovchinnikov IBCh RAS

36. © 1998-2003, Branch of Shemyakin&Ovchinnikov IBCh RAS

37. Direct Organogenesis

46. Soybean – Wayne Parrot, UGA

48. Indirect Somatic Embryogenesis

56. Rubber tree from somatic embryo CIRAD

64. Maturation and Germination (Conversion)