Sperm fertilizing potential

Burkman LJ, Coddington CC, Franken DR, Oehninger SC, Hodgen GD. 1990. The hemizona assay (HZA) assessment of fertilizing potential by means of human sperm binding to the human zona pellucida. in Keel BA and Webster B, Eds. Laboratory Diagnosis and Treatment of Infertility. Boca Raton, FL CRC Press, pp. 213-228. 

Once the spermatozoa enter the oviductal isthmus, things become more complicated. The mammalian oviductal isthmus was convincingly demonstrated to serve as a sperm reservoir or storage site after ejaculation (Figure 4) [11, 67, 71, 117, 159, 160]. (Defective, nonmotile spermatozoa and cells vwth disrupted membranes are apparently not stored they appear to be passively and rapidly transported away towards the peritoneal cavity—see [116] for a review.) Spermatozoa that are not yet capacitated, that is, immature spermatozoa that have not yet acquired fertilizing potential [80, 186], attach to the oviductal epithelium and are released only when they become capacitated, i.e., only when they acquire a state of readiness to fertilize the egg. 

Benoff, S., G.M. Centola, C. MUlan, B. Napohtano, J.T. Marmar, andI.R. Hurley. 2003a. Increased seminal plasma lead levels adversely affect the fertility potential of sperm in IVF. Hum. Reprod. 18(2) 374-383. 

Antispermatogenic effects of 1,2-dibromoethane have been observed in humans occupationally exposed to 1,2-dibromoethane (Ratcliffe et al. 1987 Takahashi et al. 1981 Ter Haar 1980). These effects include changes in sperm velocity and count. Whether or not these effects are associated with reduced fertility in humans cannot be totally addressed, since the epidemiologic study (Wong et al. 1979) was not capable of detecting such a sensitive effect. Although this study had several limitations, it indicates a potential for adverse effects of 1,2-dibromoethane on fertility. 

The concept of torsional asymmetry is not jnst an interesting abstract idea. Some years ago, fertility in some Chinese rnral commnnities was found to be below normal levels, and this was traced back to the presence of gossypol in dietary cottonseed oil. Gossypol acts as a male contraceptive, altering sperm matnration, spermatozoid motility, and inactivation of sperm enzymes necessary for fertilization. Extensive trials in China have shown the antifertility effect is reversible after stopping the treatment, and it has potential, therefore, as a contraceptive for men. 

The acrosomal process of some invertebrate sperm cells is an actin cable that sometimes forms almost instantaneously by polymerization of the actin monomers and shoots out to penetrate the outer layers of the egg during fertilization (Chapter 32). The stereocilia, the "hairs" of the hair cells in the inner ear, contain bundles of actin filaments.302 Motion of the stereocilia caused by sound produces changes in the membrane potential of the cells initiating a nerve impulse. In certain lizards each hair cell contains about 75 stereocilia of lengths up to 30 pm and diameter 0.8 pm and containing more than 3000 actin filaments in a semicrystalline array. Microvilli (Fig. 1-6) contain longitudinal arrays of actin filaments. 

The assessment of sperm quality includes measures of sperm number, anomalies, and motility, but the ability of the sperm to fertilize the ovum is not assessed. In order to increase the sensitivity for detection of fertility effects, investigation of in vitro fertilization could be considered. Another potentially more sensitive option may be the continuous breeding protocol, where the animals produce several litters instead of only one litter per pair. 

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