Follicle cell processes: a shark thing?

Follicle cell processes (FCP) are identified in two species of carcharhinid shark (Selachii) but are absent in the little skate Leucoraja erinacea (Batoidea). This suggests that FCPs are either a unique structure that evolved in selachians or were lost by the batoids after their divergence, some 280 mya. The presence of FCPs in the selachians would be consistent with the evolution of large oocytes in this group of animals.