The long-standing model of pigment cell origins is implicitly based upon a progressive fate restriction model of neural crest development and postulates the existence of a partially restricted progenitor common to all pigment cell types (i.e., a chromatoblast) [38] .
Sodium is the fourth most abundant element on earth, comprising about 2.6% of the earth's crust; it is the most abundant of the alkali group of metals. It is now obtained commercially by the electrolysis of absolutely dry fused sodium chloride.
Known as a highly reactive, silvery-white and soft metal, sodium goes by the atomic number 11 and the symbol Na. This metallic element belongs to a group of alkali metals, which also includes rubidium (Rb), potassium (K) and lithium (Li).hen combined with other elements, sodium can be very useful. These include borax, sodium thiosulfate and tri-sodium phosphates. The same thing also goes for sodium nitrate, caustic soda as well as baking soda. When added to a flame, this element can further enhance the flameâs color into a bright yellowish color.