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The hydrodynamic basis for the accumulation of spermatozoa at surfaces has been investigated. The general conclusion is that when spermatozoa arrive at a surface, they will remain there if the vector of the time-averaged thrust is directed towards that surface. This can arise in two basic ways. First, consider spermatozoa that maintain a three-dimensional(More)
Flagellar synchronisation has been observed between bull spermatozoa as they swam in a viscous medium, confined to a glass surface. This process is of interest in understanding the regulation of flagellar oscillation in general. Exact and persisting synchrony between bull spermatozoa occurred only when the spermatozoan heads were tightly coupled(More)
A study has been made of the inner dynein arm complex in the sperm flagellum of Gallus domesticus. It has been found that images of the complex made from highly contrasted, approx. 20 nm, sections are very largely compatible with images made from replicas of rapidly cryofixed material. This suggests that neither technique seriously distorts the native(More)
The complexity of the 9 + 2 flagellar axoneme has made it difficult to discover the mechanism of bend propagation. We have studied a simplified preparation of mechanically "opened-out" groups of doublet microtubules that adopt a helical, ribbon-like form. From the very long sperm of the quail, ribbons of doublets up to 130 microns long have been obtained.(More)
The sperm flagellum of Anguilla anguilla lacks outer dynein arms, radial spokes and central structures. Its characteristic motion has been obtained by studying cells swimming perpendicularly against, but not adhering to, the coverslip. The flagellum generates a sinistrally helical wave of rising, then falling, amplitude. The frequency of the wave, which can(More)
The highly motile, 9 + 0 sperm axoneme of Anguilla has inner dynein arms (IDAs) but not outer dynein arms. The in situ morphology of these IDAs is shown here to be essentially identical to the IDA morphology already seen in the axonemes of Chlamydomonas, Tetrahymena and Beroë, and in the sperm tails of echinoderms and several vertebrate species. In(More)
In this work, we examine whether the "nexin" linkages of the flagellum can extend in length to accommodate interdoublet sliding. Flagellar bends of large angle were induced in bull spermatozoa by hypotonic treatment. It is argued that this produces large interdoublet displacements that are, nevertheless, still within physiological limits. Such flagella were(More)
Demembranated sperm flagella from Gallus domesticus have been prepared by the rapid-freeze, deep-etch, rotary replica technique in order to study the three-dimensional morphology of the outer dynein arm (ODA)-ATPase complex. In general, the ODAs resemble most closely those from the sea urchin Strongylocentrotus described by W. S. Sale et al. In the 'rigor'(More)
Eukaryotic flagella and cilia have a remarkably uniform internal 'engine' known as the '9+2' axoneme. With few exceptions, the function of cilia and flagella is to beat rhythmically and set up relative motion between themselves and the liquid that surrounds them. The molecular basis of axonemal movement is understood in considerable detail, with the(More)
Motility in trypanosomes is achieved through the undulating behaviour of a single "9 + 2" flagellum; normally the flagellar waves begin at the flagellar tip and propagate towards the base. For flagella in general, however, propagation is from base-to-tip and it is believed that bend formation, and sustained regular oscillation, depend upon a localised(More)