Sermatozoa from two brothers who are not twins were found to be straight and immotile. Examinations of the sperm showed that oxygen consumption and lactic acid production were normal; viability tests showed that the percentage of dead sperm was not increased. The ultrastructural appearance of the sperm tail was normal except for a complete lack of dynein arms and some irregularities in the arrangement of the accessory fibers and the longitudinal columns of the fibrous sheath. The mitochondrial apparatus and the sperm head conform to the conventional model. According to the sliding-filament hypothesis first proposed by Afzelius (1959. J. Biophys. Biochem. Cytol. 5:269.), the arms are responsible for the bending movements of the tail. The simplest explanation for the simultaneous lack of arms and sperm motility appears to be that the two brothers have a genetic disorder involving production, assembly, or attachment of the dynein arms.

A kit from Wako Pure Chemical Industries for colorimetric determination of zinc has been evaluated for its possible use in the determination of zinc in human seminal plasma. The within-assay variation for 15 replicates of each of two seminal plasma samples having zinc concentrations (mM) of 0.43 +/- 0.025 and 6.06 +/- 0.125 (mean +/- SD) was 5.7% and 2.1%, respectively. The between-assay variation after analysis of 15 replicates of a seminal plasma sample (zinc conc. 5.6 mM) on different days was 2.3%. No interference from other metal ions present in seminal plasma was observed. The average % recovery of zinc added to seminal plasma was 102.7 +/- 1.77 (mean +/- SD). A close correlation (r = 0.996, n = 105) was found between the levels of zinc determined by the colorimetric method and that determined by atomic absorption spectrophotometry as reference method. It is concluded that the present colorimetric method, which is fast, sensitive and linear over the entire concentration range of zinc present in human seminal plasma, can be recommended for use in semen analysis laboratories.

Adrenaline (A) and noradrenaline (NA) were both found to induce platelet aggregation in citrated platelet rich human plasma, adrenaline being about 8 times more effective than noradrenaline. No effect was obtained with isoproterenol. The aggregating effect of catecholamines was stereospecific, the l‐form of NA being 30 times as effective as the d‐form. Platelet aggregation induced by A and NA could be blocked by phentolamine, phenoxybenzamine and dibenamine in the concentrations 10‐6 M, 10‐4 M and 10 ‐4 M respectively, as well as with some β‐receptor blocking agents, pronethalol and propranolol, although only in a 10‐3 M concentration. Almost no effect was observed with MJ 1999. High concentrations (10‐3 M) of both α‐ and (β‐receptor blocking agents could block adenosine disphosphate induced aggregation indicating an unspecific effect of the blockers at this concentration. Uptake of 3H‐NA and 14C‐5‐HT in the platelets was inhibited by both α‐ and β‐receptor blocking agents in concentrations from about 10 ‐5 M. There was no obvious correlation between inhibition of uptake by α‐receptor blocking agents and their effect on catecholamine‐induced aggregation indicating that uptake of A or NA was not a necessary step in catecholamine mediated platelet aggregation.

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