Amphibian yolk platelet ultrastructure visualized by freeze-etching

Leonard, Robert T.; Deamer, David W.; Armstrong, Peter B.

doi:10.1016/s0022-5320(72)80019-4

Cited by 14 publications

(6 citation statements)

References 33 publications

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“…The 20-40% increase in diameter and the 50% increase in the spacing of the microtubules in the freeze-fracture replicas cannot be due entirely to the increase in volume of water upon freezing, since this accounts for only a 9% increase in volume and is even less for glycerol-water mixtures (Newman, 1968). Leonard et al (1972) observed the lattice spacing of Xenopus yolk crystals to be 92-105/~ in thin-sectioned material, and 80-100 A in freeze-etched material using no cryoprotective agent. Olive et al (1973) examined cytochrome b~ crystals by negative staining and freeze-etching and found the spacing values to be 165 ± 5 /~ and 164 ± 5 A, respectively, for trigonal crystals, and to be 95 ± 5 A and 94 ± 6 A, respectively, for tetragonal crystals.…”

Section: Discussionmentioning

confidence: 95%

Freeze-Fracture of Microtubules and Bridges in Motile Axostyles

Bloodgood

Miller

1974

The Journal of Cell Biology

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A freeze-fracture study of the motile axostyles of the flagellate protozoa Saccinobaculus and Pyrsonympha has been undertaken in order to obtain a view of the relationships of microtubules and their cross bridges not dependent on conventional preparative procedures. Reactivation studies using isolated axostyles prepared for freeze-fracture and then thawed demonstrate that we are observing the structure of a potentially functional axostyle. Cross fractures through the axostyle demonstrate more extensive interrow bridging than expected on the basis of observations of thin-sectioned material. Each microtubule has approximately sixfold bridge-binding sites with connections to as many as four interrow bridges. Measurements of microtubule diameter and spacing are significantly larger than those made from sectioned material and may indicate that conventional processing for electron microscopy results in the loss of structurally important water within the microtubule in addition to loss of intertubule material. Longitudinal fractures through the axostyle at various orientations demonstrate a minimum longitudinal periodicity of 160 A for both the spacing of the globular subunits within the microtubule wall and the spacing of the intrarow bridges. While intrarow bridges are strictly periodic and always oriented in parallel, interrow bridges are not strictly periodic and can be oriented at varying angles to the microtubule axis.

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Section: Discussionmentioning

confidence: 95%

Freeze-Fracture of Microtubules and Bridges in Motile Axostyles

Bloodgood

Miller

1974

The Journal of Cell Biology

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“…That a similar pattern exists within guinea pig, and other (25,26) acrosomal membranes lacking any visible crystalline material after ordinary preparative procedures, detracts from the concept that the pattern is created by a crystal imprint on the pliable unit membrane. The polar portions of mouse eosinophil granule membranes (unpublished observations) and membranes limiting crystalline yolk (30) display no such membranous imprint of their content. Furthermore, the apical 6.~ THE JOURNAL OF CELL BIOLOGY • VOLUME 63, 1974 FIGURES 24 and 25 Guinea pig sperm.…”

Section: Acrosome and Plasma Membranesmentioning

confidence: 98%

Membrane Differentiations in Freeze-Fractured Mammalian Sperm

Friend

Fawcett

1974

The Journal of Cell Biology

220

116

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A correlated thin-sectioning and freeze-fracturing study has been made of guinea pig and rat spermatozoa. In sections, the cell membrane over the acrosome has a concanavalin A and ruthenium red reactive glycocalyx which exhibits an ordered pattern related to the lattice of crystalline domains within the plane of the membrane revealed by freeze-fracturing. The cleaved acrosomal membrane also shows a finer linear periodicity in some areas.The membrane over the equatorial segment of the guinea pig acrosome is marked by a palisade of oblique ridges not observed in the rat. The plasmalemma of the postacrosomal region is rich in membrane intercalated particles, many randomly dispersed, others clustered in rectilinear arrays. A particle-poor zone is found just anterior to the posterior ring. The fold of redundant nuclear envelope posterior to the ring has many nuclear pores in close hexagonal array. The nuclear envelope lining the implantation fossa is devoid of pores. When cleaved it has a particle-free central area surrounded by a broad zone of large, closely packed, hollow particles.The membrane of the mid-piece in the guinea pig (but not the rat) contains linear strands of 6-8-nm particles oriented circumferentially. The membrane investing the principal piece exhibits the usual randomly distributed particles but in addition, a double row of larger (9 nm) particles runs longitudinally within the membrane over outer dense fiber 1. In the corresponding position in thin sections a local thickening of the membrane is discernible. These observations form a basis for further studies on the functional correlates of these regional specializations of the sperm membrane.Considerable specificity exists in the interaction of sperm and egg in mammalian fertilization, a specificity which favors the recognition and attachment of gametes of the same species and discourages hybridization. Apparently this specificity resides in the membranes. In addition, there is a remarkable regional specialization of the sperm surface. Only the membrane overlying the acrosome is involved in the normal adhesion of epididymal sperm in the guinea pig and opossum (8), in the adhesion of sperm to leukocytes (unpublished observations), and in the head-to-head sperm agglutination in the presence of certain antisera (33). It is this membrane region,

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“…Electron microscopic analysis (Figure 1) indicated that the platelets were rounded rectangular plates (lower right inset) which on higher magnification revealed closely stacked lamellar arrays approximately 70 A thick not unlike those observed in other amphibians (Wallace, 1978;Karasaki, 1963;Flope et al, 1963;Honjin & Nakamura, 1967;Leonard et al, 1972). These lamellar arrays represent a crystalline structure as indicated by the optical diffractogram shown in the lower left inset.…”

Section: Resultsmentioning

confidence: 77%

“…Preliminary observations of reciprocal lattice are in agreement with orthorhombic crystals observed with other yolk platelets (Lange, 1982). A three-dimensional structure for the lipovitellin-phosvitin complex has been proposed by Ohlendorf et al (1978) andLeonard et al (1972).…”

Section: Resultsmentioning

confidence: 99%