Results 221 to 230 of about 32,366 (262)
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ULTRASTRUCTURE OF THE TAIL STUMP SPERM DEFECT IN THE BULL
Acta Pathologica Microbiologica Scandinavica Section A Pathology, 1980A characteristic major sperm defect, with about 60% of the sperm cells showing a rudimentary tail stump, was found in two sterile Danish bulls of imported origin. The condition seldom occurs, but seems to be widespread and has been observed in several breeds of cattle and in different animal species, including man.
E, Blom, A, Birch-Andersen
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How the sperm lost its tail: the evolution of aflagellate sperm
Biological Reviews, 2004ABSTRACTThe typical sperm is comprised of a head, midpiece and flagellum. Around this theme there is an enormous diversity of form ‐ giant sperm, multi‐flagellate sperm and also sperm that lack flagella entirely. Explaining this diversity in sperm morphology is a challenging question that evolutionary biologists have only recently engaged in ...
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CILIA AND SPERM TAIL ABNORMALITIES IN POLYNESIAN BRONCHIECTATICS
The Lancet, 1978Sperm tails and bronchial cilia from Polynesians with bronchiectasis were examined in the electron microscope. The outer doublet tubules of the axonemal skeleton in these organelles either lacked dynein arms or had only partial arms. Various other cilial abnormalities were common.
D, Waite +5 more
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Sept12 is a component of the mammalian sperm tail annulus
Cell Motility, 2007AbstractSince their essential role in cytokinesis was first shown in yeast, the septins have been described to function in diverse cellular contexts. The members of this unique class of GTPases are capable of binding and hydrolyzing GTP, associating with membranes and oligomerizing into higher order structures.
Jonathan D, Steels +5 more
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Computerized semen analysis with sperm tail detection
Human Reproduction, 1990We evaluated a recently developed computerized semen analyser that detects spermatozoa not only by the criteria of size, contrast and movement but also by the morphological characteristics of the sperm tail. Comparison of the sperm concentration in 33 semen samples measured by conventional and by computerized semen analysis, as well as by flow ...
J, Neuwinger, H M, Behre, E, Nieschlag
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Fine Structure of Sperm Tails of Isopods
Crustaceana, 1961[La microscopie electronique a revele un type unique de flagelle caudal chez les spermatozoides des Isopodes Cyathura sp., Idotea balthica et Oniscus asellus. Ce flagelle consiste en un long cylindre flexible (ou elastique), de 300-350 mμ de diametre, transversalement strie a travers toute son epaisseur avec une alternance reguliere de bandes denses et
Ralph A. Lewin +2 more
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The evolution of the sperm tail.
Symposia of the Society for Experimental Biology, 1983In this paper the evolution of the sperm tail is discussed. The primitive motile apparatus is assumed to be a conventional '9 + 2' axoneme which persists in all aquatic phyla having external fertilisation. Where internal fertilisation has evolved in association with terrestrial life, the sperm tail has a '9 + 9 + 2' pattern: it has acquired new ...
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What Makes Cilia and Sperm Tails Beat?
New England Journal of Medicine, 1977Since Leeuwenhoek's account of the swimming movements of spermatozoa (1677) and the description of ciliated epithelia by Purkinje and Valentin,1 biologists have been intrigued by the mechanism of m...
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Structural organization of the sperm tail
Nature Structural & Molecular Biology, 2023openaire +2 more sources
‘Billy, the Sad Sperm with no Tail’: Representations of Sperm in Children’s Books
Sexualities, 2003Books about human reproduction produced for English-speaking children both construct and perpetuate processes of social reproduction. This social reproduction takes place within the context of capitalist, patriarchal and heteronormative socio-cultural norms. Information about human reproduction is ‘processed’ and ‘distilled’ for the young - it is made
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