Departamento de Biologia, IB, UNICAMP, SP

The initial events in prostatic morphogenesis involve cell proliferation, epithelial canalization and projection toward the stroma. We have hypothesized that a stromal rearrangement takes place at the sites of epithelial growth and branching and that this rearrangement involves the action of gelatinases (MMP-2 and MMP-9). Thus, the purpose of this work was to identify structural aspects of epithelial growth during the first week of postnatal development of the rat ventral prostate (VP) and to characterize the expression of MMP-2 e MMP-9 and their localization and activity in this process, using histological, ultrastructural, and immunocytochemical studies paralleled with gel and in situ zymography, and Western blotting. An increasingly complexity of prostatic architeture was observed within the first postnatal week. Concomitantly,  the stroma became more organized and some cells differentiated into smooth muscle cells. MMP-2 and MMP-9 activities were found. MMP-2 decreased during the first week, but the lowest level observed at day 6 was still higher than in the adult VP. Developing epithelial cords showed strong gelatinolytic activity. The distribuition of this activity was similar to the distribution of MMP-2 as determined by immunocytochemistry. Reticulin fibers appeared as  a basket like arrangement at growing tips and laminin staining was fainter in these regions. These  results suggest that gelatinolytic activity (with contributions of both MMP-2 and MMP-9) in the epithelium and at the epithelium/stroma interface might be responsible for the tissue remodeling allowing epithelial growth  and its projection into the  surrounding stroma. Capes and Fapesp