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When the spermatozoon of Echinus esculentus swims in sea water containing methyl cellulose (viscosity 1.5--4 Pa s), its flagellum may generate either a helical or a planar waveform, each type being stable. The helical wave, which is dextral, is complicated by the concurrent passage of miniature waves along it. These miniature waves have a pulsatile origin(More)
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)
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)
Male mice had previously been generated in which the inner dynein arm heavy chain 7 gene (MDHC7) was inactivated by the substitution of four exons encoding the ATP-binding site (P1-loop) with the neomycin resistance gene, giving a putative non-functional gene product. We have used additional techniques of electron microscopy to determine what effect the(More)
The anterior lens capsule provides a thick, easily handled model system for the study of the organization of type IV collagen, the main component of basement membranes. We have used the technique of rapid freezing, deep-etch, and rotary replication to study the three-dimensional organization of the collagen skeleton in mammalian lens capsule after a variety(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)
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)
The ultrastructure of human spermatozoa at various stages of the freezing and thawing process was studied. In addition to conventional fixations, a freeze-substitution method was used to examine spermatozoa before they were thawed. Dilution in a glycerol-egg yolk-citrate medium caused slight swelling of the acrosome. During slow freezing, when large ice(More)