Crystal content investigation in dried human bulbo-urethral gland (Cowper's) secretion

The present study compiled the data furnished by 77 different specimens of human bulbo-urethral secretion obtained from 4 donors. It established that Cowper's fluid, allowed to dry at room temperature, gives rise to dendritic crystalline structures showing a remarkable pattern closely resembling fern leaves. In addition to the dendrites, which may develop in some other mucoid secretions and are known to be mainly composed of NaCl crystals, numberless tiny spherulites are also observed within interdendritic intervals, in the central part of the preparations. These spherulites consist of polycrystalline microstructures radiating from a central nucleus. It can be inferred from their structure and localization that they are composed of salts other than NaCl and do not crystallize in the cubic system. Far from being an occasional phenomenon, ferning crystallization is considered to be an unequivocal physical constant of dried human bulbo-urethral fluid. As for interdendritic crystalline spherulites that were described previously as occasional structures present only in ovulatory cervical mucus, both their abundance and range of size variation make them a constant and specific feature of dried Cowper's fluid.