sentences:  Although part of normal Langerhans cell histology, they also provide a mechanism to differentiate Langerhans cell histiocytoses (which are a group of rare conditions collectively known as histiocytoses) from proliferative disorders caused by other cell lines.Formation is induced by langerin.The function of Birbeck granules is debated, but one theory is that they migrate to the periphery of the Langerhans cells and release their contents into the extracellular matrix.