Glycoprotein hormone alpha-chain-immunoreactive endocrine cells in prostate and cloacal-derived tissues.

All cloacal-derived tissues contain a similar endocrine cell population. Human chorionic gonadotropin (hCG)-like immunoreactivity has been reported in some prostatic endocrine cells. On the other hand, immunoreactivity to alpha-hCG is well known to occur in a variety of extraprostatic endocrine elements. Most cloacal-derived tissues were tested with a panel of monoclonal antibodies against hCG and subunits. The previously described hCG-like positivity was found to be exclusively related to the free alpha-subunit of hCG. Moreover, alpha-chain immunoreactivity was more broadly distributed in most cloacal-derived tissues, including those from the anal canal. In the anal canal, alpha-chain was an excellent marker of the anal transitional zone. alpha-Chain-immunoreactive endocrine cells were normal and nonneoplastic constituents of these tissues; they corresponded to a subpopulation of serotonin cells. In addition, certain prostatic argyrophil cell carcinomas might be exclusively alpha-subunit producing.