Penetration of human ejaculated spermatozoa into human and bovine cervical mucus. II. Pattern and velocity of penetration

The pattern of penetration of human ejaculated spermatozoa into human cervical mucus (HCM) and bovine cervical mucus (BCM) was studied in an in vitro penetration system by means of plate capillary tubes. Sperm penetrate the HCM in a unique pattern making their way progressively forwards in a one-way direction in between the filaments. In contrast, sperm move preferably forward in BCM. The different patterns are probably due to different organizations of the glycoproteins. The penetration values (PV) were also different in the two systems when studied after short periods of incubation (15 and 30 min), but incubation for 1 h brought both systems to the same rate of PV. Thus, this period is enough to overcome the differences between the patterns of penetration. Sperm velocity in semen, in HCM, and in BCM were the same. Cervical mucus (CM) did not affect sperm velocity. A strong correlation (r = 0.8) was found between sperm velocity in the semen and its PV rate either in HCM or in BCM. The results of this study recommend the use of BCM as a reference CM in cross penetration tests and suggest its establishment as a routine method for assessment of sperm quality.