  Let X be a complex Fano manifold of arbitrary dimension, and D a prime
divisor in X. We consider the image H of N_1(D) in N_1(X) under the natural
push-forward of 1-cycles. We show that the codimension c of H in N_1(X) is at
most 8. Moreover if c>2, then either X=SxY where S is a Del Pezzo surface, or
c=3 and X has a flat fibration in Del Pezzo surfaces onto a Fano manifold Y,
such that the difference of the Picard numbers of X and Y is 4. We give
applications to Fano 4-folds, to Fano varieties with pseudo-index >1, and to
surjective morphisms whose source is Fano, having some high-dimensional fibers
or low-dimensional target.
