Photopsin absorb light at different wavelengths as retinal-bound pigments. Humans have three different photoreceptor proteins ("photopsin" or "cone opsins") which are found in cone cells and which are responsible for colour vision: George Wald received the 1967 Nobel Prize in Physiology or Medicine for his experiments in the 1950s that showed the difference in absorbance by these photopsins (see image). Photopsin Photopsins (also known as Cone opsins) are the photoreceptor proteins found in the cone cells of the retina that are the basis of color vision. Iodopsin, the cone pigment system in chicken retina, is a close analog of the "visual
Induced stem cells form whole embryos from the remaining part. This meant that the cells can change their differentiation pathway. In 1924 Spemann and Mangold demonstrated the key importance of cell–cell inductions during animal development. The reversible transformation of cells of one differentiated cell type to another is called metaplasia. This transition can be a part of the normal maturation process, or caused by an inducement. One example is the transformation of iris cells to lens cells in the process of maturation and transformation of retinal pigment epithelium cells into the neural retina during regeneration in adult newt eyes. This process allows the