The Effect of Dilution on the Activity of Spermatozoa

Abstract

(i) The relative inactivity of the spermatozoa in the undiluted sperm of Echinus is not due to the physical or chemical constitution of their natural medium in the testis, since the cells are intensely active in this medium when the majority of spermatozoa are removed by means of a centrifuge. (ii) The total activity of any suspension, as measured by its demand for oxygen, is proportional to the number of spermatozoa present and to the average distance in which each cell is free to move. Inactivity in the testis appears to be due to mechanical overcrowding, each cell appearing to exercise a restraining or allelostatic effect on the activity of its neighbours. (iii) The total energy expended during the life of a spermatozoon, as well as the level of activity exhibited immediately after activation, depends on the degree of dilution of the suspension examined. (iv) The relatively long life of concentrated suspensions is not due to the narcotic effect of accumulated CO₂, but is the result of an incomplete state of activation on the part of each spermatozoon.