  We investigate the spatial distribution of chemical abundances in a sample of
low metallicity Wolf-Rayet (WR) galaxies selected from the SDSS. We used the
integral field spectroscopy technique in the optical spectral range (3700-6850
AA) with PMAS attached to the CAHA 3.5 m telescope. Our statistical analysis of
the spatial distributions of O/H and N/O, as derived using the direct method or
strong-line parameters consistent with it, indicates that metallicity is
homogeneous in five out of the six analysed objects in scales of the order of
several kpc. Only in the object WR404, a gradient of metallicity is found in
the direction of the low surface brightness tail. In contrast,we found an
overabundance of N/O in spatial scales of the order of hundreds of pc
associated with or close to the positions of the WR stars in 4 out of the 6
galaxies. We exclude possible hydrodynamical causes, such as the metal-poor gas
inflow, for this local pollution by means of the analysis of the
mass-metallicity relation (MZR) and mass-nitrogen-to-oxygen relation (MNOR) for
the WR galaxies catalogued in the SDSS.

Cosmology and Nongalactic Astrophysics