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Updated: Aug 19, 2026

Collection of Post-mating Semen from the Female Reproductive Tract and Measurement of Semen Liquefaction in Mice
Published on: November 18, 2017
Changes in osmolality during liquefaction of human semen
Trevor G Cooper1, Jennifer P Barfield, Ching-Hei Yeung
1Institute of Reproductive Medicine of the University Clinic, Münster, Domagkstrasse 11, D-48129 Münster, Germany. cooper@uni-muenster.de
Abstract:
The osmolality of 18 liquefying human semen samples from 15 volunteers was measured by vapour pressure osmometry to be low (294 mmol/kg, range 269-311). For each sample the osmolality increased during liquefaction to reach a mean of 312 mmol/kg (280-331) by 30 min at 37 degrees C. These results are at variance with the widely held view that semen osmolality is greater than that of serum, which results from its first being examined after liquefaction in vitro. Thus when sperm are routinely examined after liquefaction they have been subjected to osmotic stresses that are not experienced by spermatozoa entering the female tract at coitus.
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