Callus induction medium consists of agar and a mixture of macronutrients and micronutrients for the given cell type. There are several types of basal salt mixtures used in plant tissue culture, but most notably modified Murashige and Skoog medium,[13] White's medium,[14] and woody plant medium.[15] Vitamins are also provided to enhance growth such as Gamborg B5 vitamins.[16] For plant cells, enrichment with nitrogen, phosphorus, and potassium is especially important.