The buccal ganglia ofHelix pomatia L. (Gastropoda, pulmonata)

1980 ◽  
Vol 95 (3) ◽  
pp. 195-212 ◽  
Author(s):  
Heinz Steffens
Keyword(s):  
Buccal Ganglia

Transmission Electron Microscopy Studies of Pore Cells in Limax Maximus

1977 ◽  
Vol 35 ◽  
pp. 656-657
Author(s):  
B. S. Beltz
Keyword(s):  
Electron Microscopy ◽  
Cell Periphery ◽  
Salivary Duct ◽  
Terrestrial Mollusc ◽  
Buccal Ganglia ◽  
Transmission Electron ◽  
Pore Cells ◽  
Gland Tissue ◽  
Storage Area ◽  
Limax Maximus

The cells which are described in this study surround the salivary nerve of the terrestrial mollusc, Limax maximus. The salivary system of Limax consists of bilateral glands, ducts, and nerves. The salivary nerves originate at the buccal ganglia, which are situated on the posterior face of the buccal mass, and run along the salivary duct to the gland. The salivary nerve branches several times near the gland, and eventually sends processes into the gland.The pore cells begin to appear at the first large branch point of the salivary nerve, near the gland (Figure 1). They follow the nerve distally and eventually accompany the nerve branches into the gland tissue. The cells are 20-50 microns in diameter and contain very small nuclei (1-5 microns) (Figure 2).The cytoplasm of the pore cells is segregated into a storage area of glycogen and an organelle region located in a band around the cell periphery (Figure 3).

Higher order neurons in buccal ganglia of Pleurobranchaea elicit vomiting motor activity

1983 ◽  
Vol 50 (3) ◽  
pp. 658-670 ◽  
Author(s):  
A. D. McClellan
Keyword(s):  
High Frequency ◽  
Motor Pattern ◽  
Higher Order ◽  
Root Activity ◽  
Command Neurons ◽  
Sensory Inputs ◽  
Buccal Ganglia ◽  
Output Pattern ◽  
Stimulation Of

The buccal mass of the gastropod Pleurobranchaea is used during a regurgitation response that consists of a writhing phase interrupted by brief periodic bouts of a vomiting phase (17, 20). During transitions from writhing to vomiting, specific changes occur in the motor pattern (19, 20). Evidence is presented suggesting that at least some of the initiation or "command" neurons for vomiting reside in the buccal ganglia. The present paper examines the role of two candidate vomiting-initiation cells, the ventral white cells (VWC) and midganglionic cells (MC), in the buccal ganglia of isolated nervous systems. Stimulation of single VWCs activates a vomiting motor pattern, consisting in part of alternating buccal root activity. Furthermore, the VWCs fire in high-frequency bursts during episodes (i.e., bouts) of this same vomiting pattern. Mutual reexcitation between the VWCs and motor pattern generator (MPG) appears to produce the accelerated buildup and maintenance of vomiting rhythms. Brief stimulation of single MCs "triggers" bouts of a vomiting motor pattern, but the membrane potential of this cell is only modulated during this same pattern, at least in the isolated nervous system. It is proposed that in intact animals the MCs are activated by sensory inputs and briefly excite the VWC-MPG network, thereby turning on the mutual reexcitatory mechanism mentioned above and switching the output pattern. A general implication for gastropod research is that higher order neurons that activate buccal root activity cannot automatically be given the function of "feeding command neuron," as some cells clearly control other responses, such as vomiting.

A System of Electrically Coupled Small Cells in the Buccal Ganglia of the Pond Snail Planorbis Corneus

1972 ◽  
Vol 56 (3) ◽  
pp. 621-637
Author(s):  
MICHAEL S. BERRY
Keyword(s):  
Synaptic Input ◽  
Action Potentials ◽  
Burst Activity ◽  
Small Cells ◽  
Pond Snail ◽  
Trigger System ◽  
Buccal Ganglia ◽  
Large Numbers ◽  
Planorbis Corneus

1. The buccal ganglia of Planorbis contain a population of electrically coupled small cells. This has been studied, in preparations of isolated ganglia, by recording intracellularly from the cells two at a time. 2. The population is usually silent but activity initiated in any one of its members tends to spread to the rest of the population in both ganglia. Failure of spread, or fatigue, gradually occurs on repetition. 3. The group has the properties of a trigger system, initiating prolonged patterned activity in large numbers of neurones in the buccal ganglia. This may normally initiate feeding. 4. In addition to central processes, both in the buccal ganglia and to the rest of the CNS, the system has peripheral axons in most of the buccal nerves. No synaptic input could be demonstrated. 5. Action potentials in some of the cells increase greatly in duration with repetition. The resulting electrotonic EPSP's, recorded in closely coupled trigger cells, correspondingly increase in size. The possible integrative significance of this is discussed, especially its effect in offsetting fatigue. 6. In some preparations spontaneous bursting occurred in trigger cells and this elicited burst activity in large neurones, including motoneurones. The system may have an intrinsic pacemaker.

Sensory Fields and Properties of the Oesophageal Proprioceptors in the Mollusc, Philine

1981 ◽  
Vol 94 (1) ◽  
pp. 77-93
Author(s):  
D. A. DORSETT ◽  
J. N. SIGGER
Keyword(s):  
Conduction Velocity ◽  
Branch Point ◽  
Repetitive Stimulation ◽  
Buccal Ganglia ◽  
Sensory Field ◽  
Oesophageal Wall ◽  
Extensive Field

1. The buccal ganglia of Philine each contain four mechanosensory neurones that are proprioceptors in the oesophageal wall. The sensory fields of the three small receptors are bilateral and separate from each other, but two are overlapped by the more extensive field of the largest cell. 2. The sensory field of each receptor overlaps that of its contralateral homologue. 3. The receptors respond to touch or stretch of the oesophageal wall or certain nerve trunks with a rapid burst of impulses, which adapt quickly to repetitive stimulation. 4. The soma spike is characterized by a large undershoot that summates at high-impulse frequencies to hyperpolarize the cell. 5. Repetitive stimulation leads to the axon spike failing to propagate to the soma. Blocking most probably occurs at a branch point on the main axon within the ganglion. 6. Impulses generated in one part of the axon normally propagate to all parts of the cell. Conduction velocity increases in the axon as the soma is approached. Conduction velocity may vary in different branches of the axon.

Synaptic Actions of Oesophageal Proprioceptors in the Mollusc, Philine

1981 ◽  
Vol 94 (1) ◽  
pp. 95-104
Author(s):  
J. N. SIGGER ◽  
D. A. DORSETT
Keyword(s):  
Receptive Fields ◽  
Large Cell ◽  
The Other ◽  
Small Cells ◽  
Sensory Cells ◽  
Periodic Activity ◽  
Buccal Ganglia ◽  
Excitatory Synaptic Input ◽  
Feeding Cycle ◽  
Protraction Phase

The buccal ganglia of Philine each contain a group of mechanoreceptors, consisting of 1 large and 3 small cells, with receptive fields in the oesophagus. Synaptic contacts occur between the receptors; the large cell providing an EIPSP input to its contralateral partner and to the two groups of smaller receptors. The small receptors make weak excitatory contacts with both the large receptors. The sensory cells synapse with other buccal motoneurones and interneurones, some of which show periodic activity associated with the feeding movements. Protraction phase neurones are divisible into two groups, one of which receives EPSPs from the receptors, while the other group receives IPSPs. Retraction phase neurones receive a biphasic EIPSP. The receptors provide excitatory synaptic input to a pair of interneurones which ‘gate’ the feeding cycle. A third class of neurones which are not rhythmically active during feeding receive a predominantly inhibitory EIPSP.

The Integration of the Patterned Output of Buccal Motoneurones During Feeding in Tritonia Hombergi

1979 ◽  
Vol 79 (1) ◽  
pp. 23-40
Author(s):  
A.G. M. BULLOCH ◽  
D. A. DORSETT
Keyword(s):  
Feeding Activity ◽  
Electrical Coupling ◽  
Cell Activity ◽  
Giant Cells ◽  
Posterior Border ◽  
Buccal Ganglion ◽  
Synaptic Inputs ◽  
Proprioceptive Input ◽  
Buccal Ganglia ◽  
Feeding Cycle

Three phases of activity may be recognized in the buccal mass of Tritonia hombergi during the feeding cycle. These have been termed Protraction, Retraction and Flattening. Each phase is driven by a group of motoneurones along the posterior border of the buccal ganglia. The patterned bursting observed in the motoneurone groups during feeding activity is phased by synaptic inputs which are common to two or more groups. Evidence is presented which indicates these inputs are derived from three unidentified multi-action interneurone sources within each buccal ganglion, and whose action primarily determines the patterned output of the motoneurones. Electrical coupling between between synergistic motoneurones and, in one case, post-inhibitory rebound, contribute to the synchronization of group activity. Proprioceptive input to the motoneurones was not identified, but may project to the interneurones. Some small neurones having synaptic inputs on the motoneurones appropriate to two of the interneurones were found, but require confirmation in this role. The cerebral giant cells synapse on representatives of three motoneurone groups, and also activate the buccal interneurones driving the feeding cycle. The patterned activity of the motoneurones can occur in the absence of cerebral cell activity.

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