FROM UNPOLARIZED TO POLARIZED QUARK DISTRIBUTIONS IN THE NUCLEON

Starting from Martin, Roberts and Stirling fit for unpolarized deep in elastic structure functions and using experimental data on spin asymme tries we get a fit which provides polarized quark distributions. We an alyze the behaviour of such functions near x equal to 1. The first mom ents of these distributions are also discussed. Our fit prefers combin ation of proton and neutron data versus proton-deuteron one.