TWO-WAY DIALOGUE. “That helper cells exert control over the reproductive cell line development is not surprising; however, evidence is accumulating that germ cells themselves regulate development of their helper populations in a complex two-way conversation, extending from the beginnings of the reproductive cell lineage in the sporophyte to the maturation of the gametes within the gametophyte.”
http://www.sciencedirect.com/science/article/pii/S1534580713000427