The Functional Anatomy of the Cornea and Anterior Chamber in Lampreys: Insights From the Pouched Lamprey, Geotria australis (Geotriidae, Agnatha)

Extant lampreys (Petromyzontiformes) are one of two lineages of surviving jawless fishes or agnathans, and are therefore of critical importance to our understanding of vertebrate evolution. Anadromous lampreys undergo a protracted lifecycle, which includes metamorphosis from a larval ammocoete stage to an adult that moves between freshwater and saltwater with exposure to a range of lighting conditions. Previous studies have revealed that photoreception differs radically across the three extant families with the Pouched lamprey Geotria australis possessing a complex retina with the potential for pentachromacy. This study investigates the functional morphology of the cornea and anterior chamber of G. australis, which is specialised compared to its northern hemisphere counterparts. Using light microscopy, scanning and transmission electron microscopy and microcomputed tomography, the cornea is found to be split into a primary spectacle (dermal cornea) and a scleral cornea (continuous with the scleral eyecup), separated by a mucoid layer bounded on each side by a basement membrane. A number of other specialisations are described including mucin-secreting epithelial cells and microholes, four types of stromal sutures for the inhibition of stromal swelling, abundant anastomosing and branching of collagen lamellae, and a scleral endothelium bounded by basement membranes. The structure and function of the cornea including an annular and possibly a pectinate ligament and iris are discussed in the context of the evolution of the eye in vertebrates.

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Calycinal trichomes in Ipomoea cairica (Convolvulaceae): ontogenesis, structure and functional aspects

Australian Journal of Botany ◽

10.1071/bt10194 ◽

2011 ◽

Vol 59 (1) ◽

pp. 91 ◽

Cited By ~ 22

Author(s):

Elder Antônio Sousa Paiva ◽

Luiza Coutinho Martins

Keyword(s):

Electron Microscopy ◽

Developmental Stages ◽

Glandular Trichomes ◽

Structure And Function ◽

Short Stalk ◽

Transmission Electron ◽

Functional Aspects ◽

Acidic Polysaccharides ◽

Low Humidity ◽

And Function

The presence of calycinal trichomes in Ipomoea has been neglected, which renders the interpretation of their functions difficult. The present work aims to characterise the structure, as well as the composition of the secretion of calycinal trichomes in Ipomoea cairica, in order to establish a relationship between their structure and function. Samples of floral buds at different developmental stages and sepals from fruits were collected and fixed for study under light as well as under scanning and transmission electron microscopy. The calyx of I. cairica is persistent and presents glandular trichomes which produce acidic polysaccharides. The trichomes are peltate and consist of a short stalk and a pluricellular secretory portion. The cells from the secretory portion contain a dense and organelle-rich cytoplasm. The fresh secretion is hyaline and fluid, but solidifies when exposed to low humidity, taking on a crystalline and fragile aspect, and they return to a gel state when in the presence of water. The calycinal trichomes in I. cairica show great structural and ultrastructural similarities to colleters and can be considered functionally analogous. The secretion, which is highly hygroscopic, spreads along the surface of the corolla and of the fruit, apparently protecting these structures against desiccation.

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New Approaches to Relating Structure and Function using Analytical Transmission Electron Microscopy

10.3390/iocc_2020-07346 ◽

2020 ◽

Author(s):

Robert F Klie

Keyword(s):

Electron Microscopy ◽

Transmission Electron Microscopy ◽

Structure And Function ◽

Analytical Transmission Electron Microscopy ◽

New Approaches ◽

Transmission Electron ◽

And Function

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Inter-individual stereotypy of the Platynereis larval visual connectome

eLife ◽

10.7554/elife.08069 ◽

2015 ◽

Vol 4 ◽

Cited By ~ 34

Author(s):

Nadine Randel ◽

Réza Shahidi ◽

Csaba Verasztó ◽

Luis A Bezares-Calderón ◽

Steffen Schmidt ◽

...

Keyword(s):

Electron Microscopy ◽

Neural Circuits ◽

Structure And Function ◽

Synaptic Connectivity ◽

Transmission Electron ◽

Platynereis Dumerilii ◽

Quantitative Analyses ◽

Left Right Asymmetry ◽

And Function ◽

Full Body

Developmental programs have the fidelity to form neural circuits with the same structure and function among individuals of the same species. It is less well understood, however, to what extent entire neural circuits of different individuals are similar. Previously, we reported the neuronal connectome of the visual eye circuit from the head of a Platynereis dumerilii larva (<xref ref-type="bibr" rid="bib16">Randel et al., 2014</xref>). We now report a full-body serial section transmission electron microscopy (ssTEM) dataset of another larva of the same age, for which we describe the connectome of the visual eyes and the larval eyespots. Anatomical comparisons and quantitative analyses of the two circuits reveal a high inter-individual stereotypy of the cell complement, neuronal projections, and synaptic connectivity, including the left-right asymmetry in the connectivity of some neurons. Our work shows the extent to which the eye circuitry in Platynereis larvae is hard-wired.

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Immuno- and affinity probes for electron microscopy: a review of labeling and preparation techniques.

Journal of Histochemistry & Cytochemistry ◽

10.1177/38.2.2405054 ◽

1990 ◽

Vol 38 (2) ◽

pp. 145-157 ◽

Cited By ~ 69

Author(s):

J W Stirling

Keyword(s):

Electron Microscopy ◽

Transmission Electron Microscopy ◽

Critical Analysis ◽

Cell Structure ◽

Structure And Function ◽

Sectioned Material ◽

Transmission Electron ◽

And Function ◽

Affinity Probes ◽

Preparation Techniques

Immuno- and affinity probes are widely used in biology and medicine, and are becoming essential tools for the elucidation of cell structure and function. This article reviews and discusses the bewildering array of probes and preparation techniques now available for the investigation of sectioned material by transmission electron microscopy, with critical analysis of their merits. Emphasis is placed on immunogold probes and methods useful for routine preparation, gathering together information that may be used to improve labeling techniques. New data on inert dehydration for the localization of sensitive epitopes without chemical or cryofixation is presented.

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Use of human autoantibodies and immunoelectron microscopy to study structure and function of the nucleolus and nuclear bodies

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100122939 ◽

1992 ◽

Vol 50 (1) ◽

pp. 506-507

Author(s):

Robert L. Ochs

Keyword(s):

Electron Microscopy ◽

Structure And Function ◽

Nuclear Bodies ◽

Nuclear Interior ◽

Coiled Bodies ◽

Interchromatin Granules ◽

And Function ◽

Conventional Electron Microscopy ◽

Perichromatin Granules ◽

Perichromatin Fibrils

By conventional electron microscopy, the formed elements of the nuclear interior include the nucleolus, chromatin, interchromatin granules, perichromatin granules, perichromatin fibrils, and various types of nuclear bodies (Figs. 1a-c). Of these structures, all have been reasonably well characterized structurally and functionally except for nuclear bodies. The most common types of nuclear bodies are simple nuclear bodies and coiled bodies (Figs. 1a,c). Since nuclear bodies are small in size (0.2-1.0 μm in diameter) and infrequent in number, they are often overlooked or simply not observed in any random thin section. The rat liver hepatocyte in Fig. 1b is a case in point. Historically, nuclear bodies are more prominent in hyperactive cells, they often occur in proximity to nucleoli (Fig. 1c), and sometimes they are observed to “bud off” from the nucleolar surface.

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Crystal Structures of Fragments D and Double-D from Fibrinogen and Fibrin

Thrombosis and Haemostasis ◽

10.1055/s-0037-1615842 ◽

1999 ◽

Vol 82 (08) ◽

pp. 271-276 ◽

Cited By ~ 8

Author(s):

Glen Spraggon ◽

Stephen Everse ◽

Russell Doolittle

Keyword(s):

Electron Microscopy ◽

High Resolution ◽

Crystal Structures ◽

Structure And Function ◽

X Ray ◽

Long Period ◽

And Function

IntroductionAfter a long period of anticipation,1 the last two years have witnessed the first high-resolution x-ray structures of fragments from fibrinogen and fibrin.2-7 The results confirmed many aspects of fibrinogen structure and function that had previously been inferred from electron microscopy and biochemistry and revealed some unexpected features. Several matters have remained stubbornly unsettled, however, and much more work remains to be done. Here, we review several of the most significant findings that have accompanied the new x-ray structures and discuss some of the problems of the fibrinogen-fibrin conversion that remain unresolved. * Abbreviations: GPR—Gly-Pro-Arg-derivatives; GPRPam—Gly-Pro-Arg-Pro-amide; GHRPam—Gly-His-Arg-Pro-amide

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Morphological and Biochemical Features Affecting the Antithrombotic Properties of the Aorta in Adult Rabbits and Rabbit Pups

Thrombosis and Haemostasis ◽

10.1055/s-0037-1615116 ◽

1998 ◽

Vol 79 (05) ◽

pp. 1034-1040 ◽

Cited By ~ 17

Author(s):

E. Nitschmann ◽

L. Berry ◽

S. Bridge ◽

M. W. C. Hatton ◽

M. Richardson ◽

...

Keyword(s):

Electron Microscopy ◽

Gel Electrophoresis ◽

Arterial Wall ◽

Structure And Function ◽

Wall Structure ◽

Matrix Structure ◽

Antithrombotic Activity ◽

Antithrombin Activity ◽

And Function ◽

Biochemical Features

SummaryWe hypothesised that there are important physiologic differences in arterial wall structure and function with respect to antithrombotic activity in the very young (pre-puberty) compared to adults. Electron microscopy, gel electrophoresis, and activity assays were used to examine differences in aorta structure and function comparing prepubertal rabbits (pups) to adult rabbits. Differences in endothelial function, extracellular matrix structure, proteoglycan (PG) distribution and glycosaminoglycan (GAG) content and function were shown. In both intima and media, total PG, chondroitin sulfate (CS) PG and heparan sulfate (HS) PG content were significantly increased in pups compared to adult rabbits. These findings corresponded to increased concentrations by mass analyses of CS GAG and DS GAG in aortas from pups. There was also a significant increase in antithrombin activity in pups due to HS GAG. In conclusion, differences in both structure and antithrombin activity of aortas from pups compared to adult rabbits suggest that young arteries may have greater antithrombotic potential that is, at least in part, related to increased HS GAG.

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