Understanding computer assisted sperm analysis (CASA) kinematics: Progressive motility


Written by Jennifer Ringwelski

One of the primary benefits of the utilization of a computer assisted sperm analysis (CASA) system is the standardized, objective classification of sperm motility and kinematics. While CASA systems can perform varied functions including calculating concentration, assessing morphology and even fluorescent assays, a precise, repeatable motility analysis has become the primary feature relied on by many researchers and production specialists across production animal species. 

While motility is a binary calculation, meaning sperm cells are either motile (moving) or static (not moving), increasing interest is being placed on identifying sub-populations of motile sperm, specifically progressively motile sperm.  The analysis of progressive motility is not as straightforward as that of motility and causes confusion in the field. 

In its simplest definition, progressive motility is the movement of sperm in a forward, straight line. With the CASA system distributed by IMV Technologies, progressively motile sperm must have a combination of minimum values for Average Path Velocity (VAP) and Straightness (STR).  Essentially, sperm need to be moving above a specific velocity along their average path and exhibit a certain degree of track compactness to be considered progressively motile.  The human eye cannot assess sperm velocity and track compactness with accuracy, therefore making progressive motility, by its accepted technical definition, impossible to qualify without CASA technology. 

The minimum parameters for progressive motility often vary from species to species.   Even within species, variation in minimum standards for progressive motility can depend on the genetic line or even genetic company. Additionally, progressive motility results can vary based on semen processing methodology (fresh versus frozen), media composition, as well as semen handling techniques.  And finally, in the best CASA systems, the minimum standards for VAP and STR used to describe progressive motility can be user-defined.  

It is notable, then, that two values of progressive motility cannot be accurately compared without knowing the variables in semen processing and the standards used to define this sperm quality parameter.  

Our global team of IMV Technologies CASA experts can help you understand CASA kinematics and technology and how it can work for you.  You can view the complete line of computer assisted sperm analysis systems on our website. 

The views expressed in IMV Technologies' blog do not necessarily represent the views of the IMV Technologies Group but solely those of the blog post's author.