Eduardo Rocha1
, David E Hinton2
and Eddie Wisse3 
1Laboratory of Histology and Embryology, Department of Microscopy, Institute of Biomedical Sciences Abel Salazar – ICBAS, University of Porto, Lg. Prof. Abel Salazar n° 2, 4099-003 Porto, Portugal
2Duke University, Nicholas School of the Environment and Earth Sciences, Division of Environmental Sciences and Policy, A-333 LSRC, Science Drive, Box 90328 Durham, North Carolina 27708-0328, United States
3Irisweg 16, 3140 Keerbergen, Belgium