Branching activity in the human prostate: a closer look at the structure of small glandular buds

Knowledge regarding cell biologic characteristics of small solid glandular buds in the prostate and their relationship with branching activity in the human prostate is still fragmentary. Our object was to demonstrate, on the basis of immunophenotype, loci that harbor the potential for branching activity within the adult human prostate. Semiserial sectioning was performed on 13 adult prostates in an effort to identify structures in the prostate that could be considered foci of growth. Selected slides were stained with biomarkers for basal/luminal cells (keratins), proliferation (MIB-1), apoptosis inhibitor (bcl-2), intercellular adhesion (E-cadherin), and stromal-epithelial interactions (tenascin-C). Results were compared with fetal and prepubertal human prostates and microdissected rat prostates. Five histologic epithelial structures were identified in 19 paraffin blocks, which on serial sectioning showed morphologic transitions with a common pattern, consisting of reduction in number and caliber of acini until small solid buds of epithelial cells were reached. Immunophenotypically, the small solid glandular buds had a basal-cell keratin phenotype, expression of bcl-2 in virtually all cells, high proliferative activity, prominent intracellular localization of E-cadherin, and enhanced periglandular tenascin-C immunoreactivity. The budding tips in fetal and prepubertal prostates revealed an immunostaining pattern identical to the small solid glandular buds in the adult, but different to the rat prostate. Our data suggest that dispersed small solid glandular buds have a capacity for growth, and as such may be considered foci of resumed reawakening branching activity with in the adult human prostate