POSTN and seminoma: Thus, due to and taking into account the high incidence of testicular tumours in dogs and the fact that they have been proposed as a model for the study of their human counterparts, the aim of the present study was to analyse the expression of POSTN and PDPN, and their possible correlation with the Ki67 antigen - a standardised prognostic factor for canine testicular tumours [34, 35] - in three different tumour types: Leydig cell tumour (LCT), Sertoli cell tumour (SCT) and seminoma (SEM).