Transplantation experiments

Transplantation of Dorsal lip of Gastrula

Spemann and Mangold transplanted the dorsal blastoporal lip of early gastrula of newt into a ventral or lateral position of another gastrula then it turned inward and developed inio the notochord and somitei. lt also induced the host ectoderm to form neural tube and all the structures necessary for a complete secondary embryo. Thus, the secondary embryo developed anolochord somites, kidneytubules etc., each of which is composed parfly of grafted and partly of induced host material/n this experiment, thus, the graft not only becomes self differentiated, but it induces the adjoining host tissue to form spinal cord and other structures including somites and kidney tubules. The organisation of the secondary embryo results in  a series of both inductive interactions and self differentiative changes host and donor tissues.

Optic Cup Experiments - Induction of Lens

ln the amphibian blastula, the presumptive eye area lies very close to the animal pole. The devetopmeni6TGyes occurs under the inductive influence of the neural tube on the overlying ectoderm .The  optic vesicles induce the head ectoderm to develop into a - placode, which differentiates to form the lens. ,ln an experiment, Spemann transplanted the optic cup of a neurula to a region away from the original presumptive eye region. The optic cup, when transplanted below the epidermis of the flank region of an early neurula induced the differentiation of a lens in the new location. This experiment proves that the flank epidermal cells still retain their competence to develop into the lens ie, the epidermal cells of the flank region rerydn totipotent even at the neurula stage.