ISSN:
1432-0878
Keywords:
Carotid body
;
Domestic fowl
;
Reciprocal synapses
;
Afferent axons
;
Ultrastructure
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
,
Medicine
Notes:
Summary Efferent and reciprocal synapses have been demonstrated in the carotid body of the domestic fowl (Gallus gallus domesticus). Synapses were also found with purely afferent morphology, but were probably components of reciprocal synapses. The general morphology of the endings suggested the presence of two types of axon, afferent axons making reciprocal and perhaps afferent synapses with Type I cells, and efferent axons making efferent synapses with Type I cells. A few axo-dendritic synapses were also found. The dense-cored vesicles associated with the afferent components of reciprocal synapses and with the possible true afferent synapses varied in diameter and core but could belong to one population of presynaptic vesicles. These observations are consistent with a new theory for the carotid body receptor mechanism. This proposes a spontaneously discharging afferent axon inhibited by an inhibitory transmitter substance released by the Type I cell via the “afferent” component of its reciprocal synapse, the “efferent” component inhibiting this release. Besides this chemoreceptor modulation of its afferent axon, the Type I cell may also have a general secretory function.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00209346
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