In this video, Silvia Azaña, an embryologist at inviTRA, explains what vacuoles in sperm are:
Vacuoles in spermatzoa are physiological structures that develop throughout the process of spermatogenesis and sperm maturation. Despite this, the causes that lead to its appearance are not clear.
These nuclear vacuoles are clearly visible as distinct concavities in the head of the sperm. They are formed from residual cytoplasm and cell organelles that are not needed, but have not been properly removed during the sperm formation process itself. Their importance lies in the fact that these sperm vacuoles have been directly linked to failures in chromatin condensation.
In any case, these vacules can only be detected when the sperm selection process is performed at high magnification. Therefore, these sperm vacules would be accurately and thoroughly assessed when performing IMSI, an intracytoplasmic injection of morphologically selected sperm, which would allow sperm with vacules to be effectively and reliably discarded.
