From 1540 inelastic interactions picked up for 3.7A GeV 16O with emulsion nuclei, we select carefully samples of 87and 61 events due to interactions of neutron(n) and singly charged particles(Z=1) respectively. New results concerning the topology of such events are displayed. The average multiplicities of shower particle for n and Z=1 stay more or less constant when compared with analogous data on P-A at similar energy. The multiplicity distributions as well as the average values of the various secondary particles are studied and compared with the calculations according to cascade evaporation model (CEM). The results lead to assume that the n or Z=1from 16O tend to collide peripherally with target emulsion or in other words to make N-N collisions.