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Polarized site of sperm entrance in the egg of a freshwater bivalve, Unio elongatulus (Mollusca, Bivalvia)
No full textWe studied the organization of the egg of a freshwater bivalve, Unio elongatulus. This egg is markedly polarized. At the vegetal pole there is a crater which constitutes the point of attachment of the growing oocyte to the ovarian wall. This has previously been interpreted as a micropyle. We show that the sperm does not enter the egg through the crater but in a differentiated region around it, mostly at its base. This region is characterized by a wrinkled surface and is the only site of the vitelline coat which specifically binds the lectin from Lotus tetragonolobus. The egg reacts explosively upon fertilization, ejecting vacuolar material from the crater. The role of this "egg reaction" in relation to the prevention of polyspermy is discussed. © 1988
Scanning electron microscopy and human sperm pathology
No full textThis paper has been carried out in order to inquire whether some of the best known human malformations can be recongnized by scanning electron microscopy. The SEM appearance of 'straight tailed', 'empty tailed', 'short tailed', 'round headed', and related to the inner structure. Straight tails and empty tails are quite evident at SEM. These defects are due to severe axonemal defects, related to dynein and tubulin deficiencies: '9+0', 'arm less' and 'axoneme less' spermatozoa are included in this category. Short tails and round heads are still more evident defects, and round heads are still more evident defects, due to complete absence of tail structures or acrosome and easily recognizable at SEM. Double spermatozoa are consistently in patients having abnormally high prolactin level and SEM is obviously sufficient for the diagnosis. Finally, spermatozoa in aged individuals show in SEM a peculiar shapse due to absence of immature stages, reduced cytoplasm, disordered axoneme. It is concluded that SEM examination is a good tool for the identification of most of the best known human sperm abnormalities
9+0" immotile spermatozoa in an infertile man
No full text“9 + 0”‐unbewegliche Spermatozoen bei einem unfruchtbaren Mann Bericht über eine eigene Beobachtung bei einem 27jährigen Mann, der kinderlos verheiratet ist. Die morphologische Untersuchung des Ejakulates ergab normalkonfigurierte Köpfe, allerdings waren die Spermatozoen sämtlich starr und unbeweglich. Alle Spermatozoen waren normal strukturiert mit dem überall vorhandenen Charakteristikum, daß ein Fehlen der Zentraltubuli und der Fortsätze, welche die sog. zentrale Scheide bilden, festgestellt ist. Die elektrophoretische Analyse der hochmolekularen Polypeptidketten, die dem Dynein zugeordnet werden, zeigte das konstante Fehlen einer Kette. Die Bedeutung der zentralen Strukturen, im allgemeinen zugehörig zum “9 + 2” Spermatozoon und die mögliche Lokalisation der Dynein‐Kette in dieser Gegend wird auführlich diskutiert. 1979 Blackwell Verlag Gmb
Effects of diadenosine polyphosphates and fluid vesicles on rabbit sperm cells
No full textMembrane vesicles were isolated from rabbit seminal plasma. Electron microscopy analyses showed the presence of numerous small, round vesicles with a diameter of about 70 nm. Determination of enzyme activities was carried out by high performance liquid chromatography and showed that the vesicles can degrade the diadenosine polyphosphates (ApnA), Ap3A and Ap4A and ATP and ADP, but not AMP. Studies of the degradation of diadenosine compounds by the vesicles present in seminal fluid showed an increasing production of AMP as the by-product and a time-dependent generation of dephosphorylated products consistent with the presence of ecto-ATP diphosphophosphatase (ecto-apyrase). In the presence of rabbit spermatozoa, AMP did not accumulate because 5'nucleotidase and adenosine deaminase, present at the surface of sperm cells, transformed AMP into adenosine and inosine. The effects of seminal fluid vesicles and diadenosine compounds on the acquisition of fertilizing capacity by rabbit spermatozoa were evaluated by Pisum sativum agglutinin fluorescein isothiocyanate conjugated staining. The results obtained with uncapacitated spermatozoa showed that the capacitating effector BSA could be substituted efficiently by the addition of diadenosine compounds and vesicles previously incubated for 2 h to the capacitative medium. Under these experimental conditions, the spontaneous acrosome reaction rate was not increased. Capacitated rabbit spermatozoa did not undergo acrosome reaction when Lot-lysophosphatidylcholine was substituted by diadenosine compounds previously incubated with vesicles. In conclusion, this study has shown that rabbit seminal fluid vesicles can degrade diadenosine compounds to AMP and that the addition of the vesicles and diadenosine compounds to uncapacitated rabbit spermatozoa favours the acquisition of the fertilizing capacity
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