[The mucus: a medium of life]

To investigate whether mucus, with its complex structure and specific functional properties, is a medium for life?

We compared cervical and nasal mucus samples collected from 45 ovulatory women consulting for sterility and 5 menopausal women respectively. We analyzed the physicochemical and functional characteristics. We also performed 266 sperm penetrability tests. We studied 32 samples using scanning electron microscope, according to Hexamethyl-Disilasane technique and the critical point drying method.

Both types of mucus had 10cm spin abilities and typical ferning patterns. The pH were similar (8.09±0.58 and 8.46±0.32 for cervical and nasal mucus, respectively) as well as the percentages of positive sperm penetration test (55.6 and 40.6 respectively). We observed similar patterns of spermatozoa mobility in both types of mucus. Under the scanning electron microscope, structures resembled woven fabric, with a stretched and rigid framework. Filaments of different diameters formed variable loose meshes. Thinner filaments linked together thicker filaments measuring between 300 and 400nm. The intermediate filaments varied between 100 and 200nm. Very thin and sparse filaments crossed the meshes, measuring between 10 to 100nm. Spermatozoa, bacteria and unspecified round cells were enmeshed in the mucus.

From this first comparative study of nasal and cervical mucus giving the proof of sperm penetration in the both mucus and the discovery of mucus produced by archaea living in extreme conditions, we suggested that mucus, from all origins, is a medium of life.