Localization of pyroantimonate-precipitable calcium in the endolymphatic sac of the tree frog, Hyla arborea japonica.

Pingret

Microscopy Res & Technique

et al. 1993

The localization of calcium in Toxoplasma gondii tachyzoites was studied at the ultrastructural level, with a cytochemical pyroantimonate precipitation method (PA) and controlled by EGTA chelating and EDX and EELS microanalyses. Appropriate conditions for material preparation, fixation and embedding, were defined. The proportion of precipitates that were either free or inside vacuoles and their distribution inside Toxoplasma appeared to be PA dose-dependent. Precipitation mainly occurred in the anterior pole of the Epon-embedded tachyzoites. EDX and EELS analyses showed that out of 30 PA precipitates inside tachyzoites, 78% contained Ca. In Melamine sections, 96% of the tachyzoites had intracellular precipitates and the membrane complex was stained; 25% of the tachyzoites inside host cells contained PA-Ca precipitates, but most of them were retained in the reticular network of the parasitophorous vacuole. Melamine embedding appeared to improve the preservation of calcium pyroantimonate precipitates.

Section: Egta Treatment Of Ultrathin Sectionsmentioning

confidence: 99%

Subcellular calcium localization in Toxoplasma gondii by electron microscopy and by X‐ray and electron energy loss spectroscopies

Pingret

Microscopy Res & Technique

et al. 1993

Microscopy Res & Technique

“…In fact, in previous studies in which EDTA chelation of thin sections was used, no extraction of Cat was seen in fibrils that cement otoconia (Fermin and Igarashi, 1985a). The same study showed that specificity of antimonate toward calcium was high, and this was corroborated by Kawamata (1990). In addition, potassium, which reacts with antimonate, is not a significant component of otoconia.…”

Section: Resultsmentioning

confidence: 91%

High resolution and image processing of otoconia matrix

Fermin

1993

This study was designed to investigate patterns of fibrils organization in histochemically stained otoconia. Transmission electron microscope and video imaging were used. These data indicate that otoconia of the chick (Gallus domesticus) inner ear may have central cores in vivo. The data also show that the ultrastructural organization of fibrils fixed with aldehydes and histochemical stains follows trajectories that conform to the hexagonal shape of otoconia. These changes in direction may contribute to the formation of a central core. The existence of central cores is important for the in vivo buoyancy of otoconia. Packing of fibrils is tighter after phosphotungstic acid (PTA) stained otoconia than with other histochemical stains, which usually produce looser packing of fibrils and seemingly larger central core. TEM of tilted and untilted material showed that turning of fibrils occurs at the points where the face angles of otoconia form and where central cores exist. Video image processing of the images allowed reconstructing a template which, if assumed to repeat and change trajectories, would fit the pattern of fibrils seen in fixed otoconia. Since it is highly unlikely that aldehyde primary fixation or PTA stain caused such drastic change in the direction of fibrils, the template derived from these results may closely approximate patterns of otoconia fibrils packing in vivo. However, if the above is correct, the perfect crystallographic diffraction pattern of unfixed otoconia do not correspond to patterns of fixed fibrils.

“…Hanken, 1992;Felisbino & Carvalho, 1999;Moriishi et al, 2005;Miura et al, 2008;Delgado-Martos et al, 2013;Gao et al, 2018). Furthermore, amphibian bones do not play an important role in calcium storage as it occurs in amniotes (Kawamata, 1990;Yaoi et al, 2003).…”

Section: Introductionmentioning

confidence: 99%

“…These differences are as follows: (i) a lack of the formation of secondary ossification centers and growth plates; (ii) chondrocytes in the epiphyseal cartilage are randomly arranged and cartilage columns are not formed; and (iii) trabecular bone formation is immature and a small number of osteoclasts and osteoblasts are present at the marrow interface between the epiphyseal cartilage and bone marrow (Trueb & Hanken, 1992; Felisbino & Carvalho, 1999; Moriishi et al, 2005; Miura et al, 2008; Delgado‐Martos et al, 2013; Gao et al, 2018). Furthermore, amphibian bones do not play an important role in calcium storage as it occurs in amniotes (Kawamata, 1990; Yaoi et al, 2003). These differences may be related to the histological differences observed in the long bones between mammals and amphibians; thus, comparing amphibian bone tissue, which is considered to retain primitive tetrapod characteristics, with that of mammals is important for understanding the evolutionary processes of vertebrate bones.…”

Section: Introductionmentioning

confidence: 99%

Diversity of cortical bone morphology in anuran amphibians

et al. 2022

The cortical bones of mammals, birds, and reptiles are composed of a complex of woven bone and lamellar bone (fibrolamellar bone) organized into a variety of different patterns; however, it remains unclear whether amphibians possess similar structures. Importantly, to understand the evolutionary process of limb bones in tetrapods, it is necessary to compare the bone structure of amphibians (aquatic to terrestrial) with that of amniotes (mostly terrestrial). Therefore, this study compared the cortical bones in the long bones of several frog species before and after metamorphosis. Using micro‐computed tomography (CT), we found that the cortical bones in the fibrolamellar bone of Xenopus tropicalis (Pipoidea superfamily) and Lithobates catesbeianus (Ranoidea superfamily) froglets are dense, whereas those of Ceratophrys cranwelli (Hyloidea superfamily) are porous. To clarify whether these features are common to their superfamily or sister group, four other frog species were examined. Histochemical analyses revealed porous cortical bones in C. ornata and Lepidobatrachus laevis (belonging to the same family, Ceratophryidae, as C. cranwelli). However, the cortical bones of Dryophytes japonicus (Hylidae, a sister group of Ceratophryidae in the Hyloidea superfamily), Microhyla okinavensis (Microhylidae, independent of the Hyloidea superfamily), and Pleurodeles waltl, a newt as an outgroup of anurans, are dense with no observed cavities. Our findings demonstrate that at least three members of the Ceratophryidae family have porous cortical bones similar to those of reptiles, birds, and mammals, suggesting that the process of fibrolamellar bone formation arose evolutionarily in amphibians and is conserved in the common ancestor of amniotes.