Critical point drying for scanning electron microscopy: a semi‐automatic method of preparing biological specimens

Hall, D.; Skerrett, E. John; Thomas, Walter

doi:10.1111/j.1365-2818.1978.tb00106.x

Cited by 13 publications

(6 citation statements)

References 12 publications

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“…We have not observed any apical concentrations of ultraviolet-absorbing pigment granules in living cells of the type reported in the papillate epidermis of freeze-dried petals by Brehm & Krell (1975). These could have been artefacts produced during the process of freeze-drying, in the manner discussed by Hall, et al (1978).…”

Section: Petal Pigmentsmentioning

confidence: 54%

“…Fresh, fully-open flowers were obtained from wild plants or cultivated plants of known origin. Standard methods of fixation and preparation (Hall, Skerret & Thomas, 1978;Daoud, 1980) were used for all work with the SEM, but fresh unfixed petals were used in all other investigations, either unmounted, or mounted in water. Fresh petal sections were cut by hand with a sharp razor blade and examined immediately.…”

Section: Methodsmentioning

confidence: 99%

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Pigment distribution, light reflection and cell structure in petals

Kay

Daoud

Stirton

1981

Botanical Journal of the Linnean Society

326

274

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Petal structure and the distribution of pigments in petals were studied in relation to the functional anatomy of petals and the ways in which petals absorb and reflect light. We examined 201 species from 60 angiosperm families. Anthocyanins, betalains and ultraviolet-absorbing flavonoids were normally confined to the epidermal cells, occurring in solution in the vacuole; carotenoids were found in the epidermis and in smaller quantities in the mesophyll, normally in chromoplasts. In a few species, mainly blue-flowered members of the Boraginaceae and Liliaceae-Scilleae, anthocyanins were confined to the mesophyll.Six basic kinds of petal epidermis anatomy were found, sometimes in combination; papillate (1 12 species) and multiple-papillate (13 species), in which the conical-papillate form of the cells traps incident light and scatters emergent light, with surface striations aiding these functions in many cases; reversed-papillate (4 species), multiple reversed-papillate (29 species), lenticular (32 species) and flat ( I 1 species), all with surfacestriations in some cases. Light is usually reflected from petals mainly by an aerenchymatous unpigmented reflective mesophyll; in certain species this is replaced by a reflective layer of starch grains in the upper mesophyll.

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Section: Petal Pigmentsmentioning

confidence: 54%

Section: Methodsmentioning

confidence: 99%

Pigment distribution, light reflection and cell structure in petals

Kay

Daoud

Stirton

1981

Botanical Journal of the Linnean Society

326

274

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“…Numerical forces of tensile stress on tissue evaporation have been estimated anywhere from 5.84 MPa to 4.68 GPa. 16 This would help explain the split artifact created during processing. It would be difficult to imagine how mechanically fracturing the articular cartilage specimen by hand could create pure tensile stresses initially on the surface lamina and underlying fibers, allowing the radial pattern to be exposed in all three zones.…”

Section: Discussionmentioning

confidence: 99%

A Review of the Collagen Orientation in the Articular Cartilage

2021

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Objective There has been a debate as to the alignment of the collagen fibers. Using a hand lens, Sir William Hunter demonstrated that the collagen fibers ran perpendicular and later aspects were supported by Benninghoff. Despite these 2 historical studies, modern technology has conflicting data on the collagen alignment. Design Ten mature New Zealand rabbits were used to obtain 40 condyle specimens. The specimens were passed through ascending grades of alcohol, subjected to critical point drying (CPD), and viewed in the scanning electron microscope. Specimens revealed splits from the dehydration process. When observing the fibers exposed within the opening of the splits, parallel fibers were observed to run in a radial direction, normal to the surface of the articular cartilage, radiating from the deep zone and arcading as they approach the surface layer. After these observations, the same samples were mechanically fractured and damaged by scalpel. Results The splits in the articular surface created deep fissures, exposing parallel bundles of collagen fibers, radiating from the deep zone and arcading as they approach the surface layer. On higher magnification, individual fibers were observed to run parallel to one another, traversing radially toward the surface of the articular cartilage and arcading. Mechanical fracturing and scalpel damage induced on the same specimens with the splits showed randomly oriented fibers. Conclusion Collagen fiber orientation corroborates aspects of Hunter’s findings and compliments Benninghoff. Investigators must be aware of the limits of their processing and imaging techniques in order to interpret collagen fiber orientation in cartilage.

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“…Each preparatory method for critical point drying produced leaf cuticles which were wrinkled; although the wrinkling might be reduced by altering conditions during CPD as was done by Hall et al (1978), the major condemnation of CPD was the evidence that the surface of the runner bean cuticle had been eroded.…”

Section: Discussionmentioning

confidence: 99%

An evaluation of methods for preparing easily damaged cuticular surfaces of plants for scanning electron microscopy

Eveling

McCall²

1983

Journal of Microscopy

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SUMMARY Techniques were tested to ascertain the best method for preparing the surfaces of delicate plant cuticles for microscopic examination at magnifications not exceeding 10,000. Using scanning electron microscopy, comparative examinations were made of cuticles of fresh material, ambient dried, freeze dried, critical point dried, and frozen material kept at low temperature. Micrographs were compared with material examined using light microscopy which acted as a control at low magnification. Cuticles of the leaves of runner bean, Coleus and the petals of Nicotiana, showed best surface preservation and least wrinkling when frozen, held at low temperature, and examined on a cryostage.

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Critical point drying for scanning electron microscopy: a semi‐automatic method of preparing biological specimens

Cited by 13 publications

References 12 publications

Pigment distribution, light reflection and cell structure in petals

Pigment distribution, light reflection and cell structure in petals

A Review of the Collagen Orientation in the Articular Cartilage

An evaluation of methods for preparing easily damaged cuticular surfaces of plants for scanning electron microscopy

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