A new crystallographic approach to fern-like microstructures in human ovulatory cervical mucus.

A new approach to fern-like structures in dried ovulatory cervical mucus has been carried out. Polarizing microscopy and conventional X-ray devices permitted these well-known structures to be demonstrated as being, both in nature and structure, more complex than previously described. The core of the dendrites appears to be mainly composed of NaCl, but also of KCl. They appear, under the polarizing microscope, as isotropic crystals. Anisotropic structures can be observed either at the periphery of the dendrites or isolated as small spheroliths. Anisotropic structures are insensitive to temperature variations but highly hygroscopic. They become rapidly amorphous when placed at room temperature without caution. The anisotropic period, 7 days long, is inscribed within the ferning period. Maximum anisotropy corresponds to the maximum production of cervical mucus, spinability value and basal body temperature rise. Anisotropic structures may be considered to be characteristic structures occurring spontaneously in ovulatory cervical mucus. These newly described structures consist of sodium or potassium sulphates.