Laser light scattering measurements of sperm motility have traditionally assumed spermatozoa to behave as point scatterers at small forward scattering angles, and motile cells to exhibit an isotropic distribution of translation vectors. Such assumptions have lead to interpretations of fluctuations in the detected optical field as arising from Doppler-beats. Experimental and theoretical results presented in this thesis show that for bull spermatozoa, the large dimensions (>> λ) and slab-like conformation of the rotating head result in large intensity fluctuations at the photodetector which call into question the role of coherence and render the Doppler-beat interpretation untenable. A sharply peaked scattering lobe (width ~ 20°) lying in the equatorial plane of the head is shown to give an intensity peak when the normal to the head plane becomes aligned with the scattering vector. Consequently only those motile cells swimming with appropriately aligned translation vectors contribute to the detected signal. Immotile cells, which are shown to exhibit geotaxis, become visible only to a detector aligned in the horizontal plane. A marked concentration dependence in the ratio of motile and immotile autocorrelation components is modelled on the basis of hydrodynamic interactions between motile and immotile fractions, which result in immotile cells being reoriented outside the range of visible alignments. A complex opto-dynamic system is defined by a series of experiments which demonstrate that the traditional laser light scattering geometry gives only an empirical measure of the percent motile spermatozoa but may be used to obtain an absolute measurement of the head rotation rate. Discussion is given to variations in the scattering geometry and sample chamber design which are more appropriate to the phenomenology within the system.