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Biomedical subjects

B U Budelmann

Publications and source records attributed to B U Budelmann.

27 records · Page 2Linked to original sources
PubMed1990

Physiological color change in squid iridophores. II. Ultrastructural mechanisms in Lolliguncula brevis.

Evidence is presented that changes in the optical properties of active iridophores in the dermis of the squid Lolliguncula brevis are the result of changes in the ultrastructure of these cells. At least two mechanisms may be involved when active cells change from non-iridescent to iridescent or change iridescent color. One is the reversible change of labile, detergent-resistant proteinaceous material within the iridophore platelets, from a contracted gel state (non-iridescent) to an expanded fluid or sol state when the cells become iridescent. The other is a change in the thickness of the platelets, with platelets becoming significantly thinner as the optical properties of the iridophores change from non-iridescent to iridescent red, and progressively thinner still as the observed iridescent colors become those of shorter wavelengths. Optical change from Rayleigh scattering (non-iridescent) to structural reflection (iridescent) may be due to the viscosity change in the platelet material, with the variations in observed iridescent colors due to changes in the dimensions of the iridophore platelets.

Acetylcholine↗
PubMed1988

A lateral line analogue in cephalopods: water waves generate microphonic potentials in the epidermal head lines of Sepia and Lolliguncula.

Many cephalopods have lines of ciliated cells on their head and arms. In the cuttlefish Sepia and the squid Lolliguncula, electrophysiological recordings clearly identify these epidermal lines as an invertebrate analogue to the mechanoreceptive lateral lines of fish and aquatic amphibians and thus as another example of convergent evolution between a sophisticated cephalopod and vertebrate sensory system. Stimulation of the epidermal lines with local water displacements, generated by a vibrating sphere, causes receptor potentials that have many features known from lateral line microphonic potentials. The minimal threshold of the head lines is 0.2 micron peak-to-peak water displacement (calculated at the skin surface) at 75-100 Hz.

Action Potentials↗
PubMed1982

Histochemical evidence for catecholamines as neurotransmitters in the statocyst of Octopus vulgaris.

Formaldehyde-induced fluorescence (Falck-Hillarp technique) provided histochemical evidence for the presence of catecholamines in the sensory epithelia (macula and crista) of the Octopus statocyst. A specific bright green fluorescence occurred in the neuronal plexus beneath the receptor cell layers of the epithelia and in the appropriate nerves. The histochemical findings are discussed with reference to the well-known neuronal and synaptic organization of the epithelia and to relevant results in cephalopods as well as in other molluscs. All data support the hypothesis that in the receptor systems of the Octopus statocyst catecholamines (probably dopamine and/or noradrenaline) act as neurotransmitters in the efferent fibre system.

Animals↗
PubMed1979

Hair cell polarization in the gravity receptor systems of the statocysts of the cephalopods Sepia officinalis and Loligo vulgaris.

The complete patterns of polarization of the sensory epithelia of the various gravity receptor systems of the decapods Sepia and Loligo have been described (Fig. 6). Each individual receptor cell (hair cell) bears up to 150 kinocilia, but is polarized unidirectionally by 3 morphological features: (I) by the orientation of the internal 9X2+2 tubuli structure of each kinocilium, (II) by the location of their basal feet. Each hair cell is additionally polarized (III), in that its kinociliary group is inclined toward the plane of the macula surface, forming an angle of 40-60 degrees with it (Figs. 1-3); the direction of polarization, as given by the ultrastructural features (I and II), is always opposite to this acute angle (Fig. 4). The results are discussed with reference to their physiological consequences.

Acoustic Maculae↗
PubMed1977

Secondary sensory cells in the gravity receptor system of the statocyst of Octopus vulgaris.

The presence of secondary sensory cells in the Octopus gravity receptor system has been demonstrated. In serial thin sections of the receptor cells (hair cells) no axons were found leaving the cells. Instead, synapses were observed with synaptic vesicles lying inside the receptor cells. Both data clearly indicate that the receptor hair cells represent secondary sensory cells. In addition, efferent contacts to the receptor cells could be confirmed.

Animals↗