The complex of glycan structure is synthesized by glycosyltransferases and the differential expression of glycans during development is due to the developmental expression and activity of glycosyltransferases 复杂的糖链结构是由糖基转移酶依此加工合成的,糖基转移酶在发育过程中的表达水平及生物活性决定了某一特定糖链在发育中的表达变化。