Functional Correlates of Fine Structure in the Heart of Achatinidae

Nisbet, R. H.; Plummer, J. M.

doi:10.1007/978-3-0348-6800-6_4

Cited by 22 publications

(6 citation statements)

References 21 publications

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“…In molluscs other than Lymnaea there have been only a few reports of possible peripheral neurosecretion. Cottrell & Osborne (1969) des cribe a neurohaemal complex in the heart of Helix , though similar structures observed in the hearts of Archachatina (Baxter & Nisbet 1963;Nisbet & Plummer 1966) and Helisoma and Helix aspersa (Simpson 1969) are regarded by these authors as neuromotor rather than neuro secretory. An equivalent structure in Lymnaea heart has not yet been identified.…”

Section: Reasons For Peripheral Release Of Neurohormonesmentioning

confidence: 92%

The anatomy of neurosecretory neurones in the pond snail Lymnaea stagnalis (L)

Swindale

Benjamin

1976

Phil. Trans. R. Soc. Lond. B

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The anatomy of three neurosecretory cell types in the central nervous system (c.n.s.) of the gastropod mollusc Lymnaea stagnalis (L.)- the Dark Green Cells, Yellow Cells and Yellow-green Cells-has been studied by using bright and dark field illumination of material stained for neurosecretion by the Alcian Blue-Alcian Yellow technique. The neuronal geometry of single and groups of neurosecretory cells of the various types has been reconstructed from serial sections, and the likely destination of most of their processes has been determined. Dark Green Cells are monopolar, occur exclusively within the central nervous system (c.n.s.), have few or no branches terminating in neuropile, and send axons to the surface of the pleuro-parietal and pleuro-cerebral connectives. The majority of Dark Green Cell axons however (80-85%), project down nerves which innervate ventral and anterior parts of the head-foot, the neck and the mantle. Dark Green Cell axons can be found in small nerves throughout these areas, and may terminate in a find plexus of axons on the surfaces of the nerves. Since previous experimental work has shown that the Dark Green Cells are involved in osmotic or ionic regulation, these results suggest that the target organ of the Dark Green Cells may be the skin. Yellow Cells occur both within and outside the c.n.s. They are usually monopolar, but can be bipolar. They have several axons which normally arise separately from a single pole of the cell body, or close to it. One or more processes leave the cell proximal to the point where separate axons arise, and may run unbranched for some distance through neuropile before terminating in fine brances and blobs of various sizes. These branches may release hormone inside the c.n.s. Yellow-green Cells are mono-, bi- or multi-polar, and like the Yellow Cells are found both within and outside the c.n.s. Some Yellow-green Cells, though not all, have projections which terminate in neuropile in fine branches and blobs. Yellow-green Cell bodies which occur in nerves can project back along the nerve into the c.n.s. The axons of Yellow Cells and Yellow-green Cells project to release sites in various ways. Some project into the connective tissue shealth of the c.n.s., which serves as a neurohaemal organ, either directly through the surface of a ganglion, or from the pleuro-cerebral or pleuro-parietal connectives. Other axons leave the c.n.s. via nerves leaving the left and right parietal and visceral ganglia; projections into the intestinal, anal, and internal right parietal nerves being most numerous. Axons which may be from either, or both Yellow Cells and Yellow-green Cells, can be found along the entire unbranched lengths of these nerves, and in subsequent branches which innervate organs lying in the anterior turn of the shell. All of these orgnas are closely associated with the lung cavity...

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Section: Reasons For Peripheral Release Of Neurohormonesmentioning

confidence: 92%

The anatomy of neurosecretory neurones in the pond snail Lymnaea stagnalis (L)

Swindale

Benjamin

1976

Phil. Trans. R. Soc. Lond. B

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“…Where the surface membrane of a muscle fibre faces one of these extracellular zones (arrows, figure 7), it contains dense granular material along the cytoplasmic surface. Baxter & Nisbet (1963) and Nisbet & Plummer (1966) have described apparently similar structures in gastropod cardiac muscle. These zones do not penetrate between the innermost layer of muscle cells lining the basement membrane.…”

Section: The Blood Vesselsmentioning

confidence: 83%

“…In the present paper rather similar tunnels to those mentioned above in the octopus fibrous glia were seen between the smooth muscle cells (cf. Baxter & Nisbet 1963;Nisbet & Plummer 1966) of the artery walls. Here also they presumably facilitate metabolic exchange and perhaps can be regarded as analogous to the vasa vasorum of the large arteries of vertebrates.…”

Section: Discussionmentioning

confidence: 99%

Electron microscopy of the glio-vascular organization of the brain of octopus

1969

Phil. Trans. R. Soc. Lond. B

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The glio-vascular organization of the octopus brain has been studied by light and electron microscopy. The structure of the walls of the blood vessels has been described. Two types of neuroglia can be recognized, the fibrous and protoplasmic glia; also enigmatic dark cells. Most blood vessels in the neuropil are surrounded by extracellular zones containing collagen. These zones give off glio-vascular tunnels (strands) that penetrate the neuropil in a complex network. The extracellular zones and tunnels contain in addition to collagen, smooth muscle cells and fibrocytes. Glial processes surround the extracellular zones and incompletely partition them from the neuropil. The small neuronal perikarya have no glial folds around them. The medium-size cells have thin glial sheets or finger processes related to their surfaces, which may indent the cells to form small trophospongia. The large neurons of the suboesophageal lobe have complex glial sheaths interspersed with extracellular channels. Both penetrate the neurons to form complex trophospongia. A new form of extracellular material has been observed in these extracellular channels. The occurrence of trophospongia in vertebrate and invertebrate neurons may be correlated with the absence of dendrites. Special problems discussed include the nature of the trophospongial function, the question of fluid-filled extracellular zones and their possible function as lymph channels, and the presence in some of them of haemocyanin molecules identical with those in the blood vessels. Perhaps of special importance is the observation that the lobes of the octopus brain are permeated with extracellular tunnels containing smooth muscle fibres, but it still needs to be determined whether or not the muscle cells in the tunnels of the neuropil actively contract and massage the neuropil to facilitate metabolic and other exchanges.

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“…The auricle contracts about four times per min, the ventricle about fifteen times per minute. Thus, although it is known that in the isolated heart the auricle can drive the ventricle (Nisbet and Plummer, 1968), the the normal animal it appears to behave as a conduit for much of the time.…”

Section: (D) Movement and Feedingmentioning

confidence: 99%

THE LIFE OF ACHATINIDAE IN LONDON<subtitle>Presidential Address</subtitle>

1974

Journal of Molluscan Studies

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Functional Correlates of Fine Structure in the Heart of Achatinidae

Cited by 22 publications

References 21 publications

The anatomy of neurosecretory neurones in the pond snail Lymnaea stagnalis (L)

The anatomy of neurosecretory neurones in the pond snail Lymnaea stagnalis (L)

Electron microscopy of the glio-vascular organization of the brain of octopus

THE LIFE OF ACHATINIDAE IN LONDON<subtitle>Presidential Address</subtitle>

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