sentences:  Some sperm have enlarged regions containing mitochondria, which may help in prolonging the life of the sperm while stored in the ovary.In some genera, sperm clumping and patterns of arrangement are observed in the sperm ducts and storage regions.In the tribes Xenobryconini (in the genera "Tyttocharax", "Scopaeocharax", and "Xenurobrycon") and Glandulocaudini, there is a form of sperm packaging which would allow for a higher sperm density during transfer from the male to the female.