Determination of the Functional Membrane Integrity of Mice Spermatozoa Using the Classic Hypoosmotic Swelling Test (HOST) and Modified Host

Abstract

The hypo-osmotic swelling test (HOST) is widely used in determining sperm quality by evaluating membrane integrity in both human and animal spermatozoa. The test measures the swelling ability and membrane integrity of functional sperm in hypo-osmotic solutions. The ability of the sperm membrane to maintain equilibrium between itself and the environment indicates a functional and intact plasma membrane. This functionality is depicted by the coiling and ballooning or "swelling” of the sperm tail when influx of fluid occurs due to hypo-osmotic stress. The modified HOST solution consists of Earle's Buffer Salt Solution (EBSS) while the classic HOST solution consists of sodium citrate and fructose. It has been reported that modified HOST solution show more rapid sperm tail swelling and better viability in human sperm cells. This study aims to compare the swelling ability and viability of mouse sperm upon incubation in classic HOST medium and modified HOST medium. Iso-osmotic solution was used as negative control, while distilled water acts as positive control. Caudal epididymal sperm from twenty mature male mice were collected into Kreb Ringer's Buffer medium and divided into 4 batches, one for each test solution. Sperm were pooled and discarded of cell debris and centrifuged in a discontinuous Ficoll gradient (45% and 90%). Sperm were collected at the pellet and incubated for 60 minutes in the respective test solutions. Tail swelling and viability were observed from smears taken at intervals of 5 minutes. ANOVA analysis showed no significant difference between the classic HOST and modified HOST in sperm ‘ballooning' and sperm viability. The results suggests that using modified HOST showed no significant improvement from classic HOST in functional membrane integrity changes in mouse spermatozoa as compared to human spermatozoa.