Application of Poisson distribution theory to the zona-free hamster oocyte penetration test to assess sperm function of men with asthenozoospermia

Abstract

Summary. Assessments of the penetrating potential of human spermatozoa were carried out using the zona-free hamster oocyte penetration test on 4 groups of subjects exhibiting (1) normal fertility, (2) idiopathic asthenozoospermia(< 40% motility), (3) asthenozoospermia associated with varicocoele and (4) oligoasthenozoospermia (<20 \m=x\106 spermatozoa/ml and <40% motility). When the Poisson model was used to correct the results of the in-vitro penetration experiments for differences in motile sperm concentration, significant differences were apparent between the normal fertile controls and all 3 categories of asthenozoospermic patient. Furthermore, the penetrating ability of the motile spermatozoa from patients presenting with a varicocoele or oligoasthenozoospermia was significantly less than that for the group in which asthenozoospermia was the only detectable defect. These results emphasize the practical significance of the Poisson model in the analysis of male fertility and demonstrate that the asthenozoospermic condition is associated with a significant reduction in the fertilizing potential of the motile spermatozoa.

Application of a Poisson-gamma model to study the influence of gamete concentration on sperm-oocyte fusion in the zona-free hamster egg penetration test

“…where represents the gamma function. This model is found, empirically, to give a satisfactory fit to real data, both in the present paper as well as in a recent study of asthenozoospermic patients (Aitken & Elton, 1986). The distribution of observed values of t for fixed nx generated by the Poisson and gamma models is a negative binomial (Johnson & Kotz, 1969).…”

“…Once the distribution of has been characterized for the normal fertile population, maximum likelihood methods can be used to give likelihood ratio tests for comparing the above parameter values with those recorded for other groups of men (Aitken & Elton, 1986; R. A. Elton & R. J. Aitken, unpublished observations). The model can also be applied to the testing of individual sperm samples against a data base of results obtained for a defined population, in this case the normal fertile population.…”

“…Relationship between the observed frequency distribution of hamster egg penetration rates and the fitted distributions of based on the estimates of and r presented in Table 1 and represented as continuous curves, (a) Preincubation for 7 h with Medium BWW (Aitken et al, 1982); = 26; (b) and (e) 3-h preincubation with 100 µ and 50 µ 23187 respectively (Aitken et al, 1984b), = 55 and 17 respectively. Equivalent curves for the hyperosmotic system (Aitken et al, 1983) have been published (Aitken & Elton, 1986). All penetration assays were carried out using a total sperm concentration of 10 106/ml and the results were subse¬ quently corrected for a motile sperm concentration of 5 106/ml using the Poisson model (Aitken & Elton, 1984).…”

Residual sperm function in oligozoospermia induced by testosterone enanthate administered as a potential steroid male contraceptive

“…The final pellet was resuspended at a maximum density of 20 X 10' sperm ml-I. However, in the oligozoospermic samples it was not always possible to attain the desired density of 20 X 10' sperm ml-' and to standardize the HOP assay in such samples, penetration rates were corrected as described by Aitken & Elton (1986). A minimum sperm density of 100000 ml-' was required to perform the assay.…”