Flagellar propulsion of human sperm in cervical mucus 1

Abstract

A new model was developed to characterize the hydrodynamics of the interaction between spermatoza and cervical mucus. In this model the local environment about a length element of a spermatozoon in the mucus is represented as a cell consisting of a Newtonian fluid within a rigid, cylindrical no-slip boundary. Such a cell models the mucous microstructure in the sense of “hydrodynamically equivalent” properties. A simple resistive force theory for sperm hydrodynamics was developed and applied to a human spermatozoon swimming within a mucous cell. The results included the prediction that the drag on the sperm head has a substantial effect on swimming speed. This prediction was tested experimentally, by analyzing high-speed cine films of normal and headless human spermatozoa swimming in mucus. The theoretical result was confirmed, and a cell size of the order of 2 μm was suggested.