Abstract
An electronic sizer (Coulter Counter) was utilized to determine the effects of four solutions of different osmolarities on cell volume of spermatozoa from two ejaculates from each of 17 bulls. Spermatozoa snowed a decrease in volume in the hypertonic medium. A portion of the population of cells showed a marked increase in cell volume in the hypotonic medium. This increase was associated with live cells. Sperm cells killed by freezing and thawing did not show osmotic behavior. The absolute mean volumes for spermatozoa at the time of measurement in iso-osmotic saline or Tris, hypo-osmotic saline, hypo-osmotic saline with killed spermatozoa, hyperosmotic Tris and hyperosmotic Tris with killed spermatozoa were estimated to be 25.2, 23.1, 32.4, 20.8, 20.0 and 20.4 µ3, respectively. Since dead cells change little, swelling of live cells can be much greater than mean values indicate. These results clearly show the need to control osmolarity in studies of sperm cell size. Protoplasmic droplets were found to be osmotically reactive. Their mean volume in 0.87% saline was estimated to be 8.3 µ3. The droplets appeared to rupture in hypo-osmotic media or upon freezing, leaving only debris visible microscopically. Thus, they may contribute materials to seminal plasma, which could alter its composition, unless the droplets are removed promptly after ejaculation. Bulls contribtued the major source of variation excepting in treatments in which the spermatozoa were frozen before sizing. The significant bull effect in the four sizing media was significantly correlated with the motility at the time of sizing, but not with the bulls' fertility. Copyright © 1969. American Society of Animal Science . Copyright 1969 by American Society of Animal Science