In vitro effects of nicotine on human spermatozoa

Washed human spermatozoa from 12 normozoospermic donors were treated with different concentrations of nicotine 0.1, 1.0, 5.0 and 10.0 mm and were compared to spermatozoa suspended in nutrient medium only (control). Computer-aided sperm analysis was used to assess sperm kinematic properties after 30, 60, 120 and 180 min of incubation. Viability was assessed by means of a dye exclusion staining technique (eosin/nigrosin), while acrosome-reacted cells were identified under a fluorescent microscope using fluorescein isothiocyanate-Pisum sativum agglutinin as a probe. Nicotine significantly reduced total motility, progressive motility, curvilinear velocity, amplitude of lateral head displacement, beat cross-frequency, viability and caused spontaneous acrosome reaction at concentrations of ≥5.0 mm after 2 and 3 h of exposure. Nicotine concentrations of 0.1 and 1.0 mm had no significant effect (P < 0.05) on spermatozoa except that 1.0 mm significantly decreased (P < 0.05) sperm progressive motility at 2 and 3 h of incubation as well as viability after 3 h of incubation. This study concludes that the occurrence of high levels of nicotine in the body and seminal fluid might adversely affect fertilisation capacity of human spermatozoa through a mechanism that involves decreased motility, viability and premature induction of the acrosome reaction.

Modes of acrosin functioning during fertilization

Mammalian fertilization is a complex process that involves gamete recognition, penetration, and fusion. Biochemical studies that identified the role of acrosome components during sperm-ova interaction especially the zona pellucida (ZP) provided major advances in sperm cell biology. Acrosin (a typical serine protease) functions during fertilization in several significant ways which include: a) activation of acrosome components, b) secondary binding with the ZP, and c) hydrolysis of the ZP. However, studies using knockout (KO) acrosin-deficient mice cast doubt on the traditional role of acrosin in fertilization. The KO acrosin-deficient mice exhibit normal fecundity except for delayed fertilization. Despite the doubt cast on the traditional role of acrosin by the KO acrosin-deficient mouse studies, acrosin still remains a major protease involved in multiple processes of fertilization. In this review, we assess the functional profile of acrosin and briefly summarize recent findings on proteases involved in fertilization. We propose a refined scheme for the functional role of acrosin in fertilization. We particularly emphasize the role of acrosin in acrosome exocytosis and activation of other acrosome components based on advanced technology like structural X-ray analysis.

A survey on the status of semen analysis in 118 laboratories in China

Collecting baseline information on how laboratories perform testing is a reasonable first step towards establishing intra- and inter-laboratory standardization and quality control for semen analysis. We carried out a survey of the laboratories performing the testing in Mainland China. A questionnaire, composed of 36 questions covering all aspects of semen analysis, was designed, and a copy was distributed to each of the 145 laboratories. Of these, 118 laboratories completed the questionnaires. The survey results showed that semen volume was measured visually in 53.6% (59/110) of the responding laboratories, and 70.9% (73/103) of laboratories analysed incompletely liquefied semen without any treatment. In addition, both manual-microscopic and computer-assisted semen-analysis systems were applied to analyse sperm concentration, motility and morphology. However, more than five methods were employed in routine sperm staining. An enzyme-linked immunosorbent assay was commonly used for determining whether antisperm antibodies were present. Several seminal biochemical markers were analysed in only 27.1% (32/118) of the responding laboratories. Generally, there was a lack of intra- and inter-laboratory quality control measures for semen analysis in all laboratories responding to this survey. In conclusion, the methods of semen analysis and the interpretation of test results in the surveyed laboratories differed markedly. In particular, many laboratories employed methods other than those recommended by the World Health Organization Laboratory Manual for the Examination of Human Semen and Spermcervical Mucus Interaction (1999). These findings suggest an urgent need for the standardization of semen analysis with acceptable quality controls for each parameter to make the results repeatable and meaningful.