Browsing by Author "CLAPS, A"

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    SEGREGATION OF COARSE AND FINE GLOSSOPHARYNGEAL AXONS IN THE VISCERAL NUCLEUS OF THE TRACTUS SOLITARIUS OF THE CAT
    (1989) CLAPS, A; TORREALBA, F; CALDERON, F
    The projections of coarse and fine axons of the glossopharyngeal (IX) nerve upon the caudal two thirds of the nucleus of the tractus solitarius (NTS) were studied in the cat. These afferents convey the chemo- and baroreceptor activities from the carotid receptors. We applied the Fink-Heimer method on brainstem sections, at different survival times, after a petrosal ganglionectomy. A segregation of fine and coarse fibered components was observed. Degeneration of coarse axons was mostly found in the lateral NTS, while fine fiber degeneration was predominant in regions of the medial and commissural NTS. The injection of WGA-HRP in the different NTS divisions demonstrated that the lateral NTS was mainly innervated by the set of largest neurons of the petrosal ganglion and that the medial and the commissural NTS were innervated by the set of smaller neurons of the ganglia. These results were discussed in relation to cytoarchitecture, myeloarchitecture, distribution of normal axons, and known central connectivity of the different NTS divisions. We concluded that coarse and fine visceral afferents of the IX nerve, which includes the afferents of the carotid body and the carotid sinus, represent different afferent populations that project to particular divisions of the NTS and connect to different central pathways.
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    THE CAROTID-BODY CONNECTIONS - A WGA-HRP STUDY IN THE CAT
    (1988) CLAPS, A; TORREALBA, F
    Previous neuroanatomical studies described the central representation of the carotid sinus nerve, but did not differentiate the projections of the baroreceptors from the chemoreceptors present in the carotid bifurcation. In this research we investigated the individual territories occupied by the primary afferents from the carotid body in the brainstem of the cat. We also studied the distribution of afferent and efferent neurons to the carotid body. We injected into the carotid body lectin coupled to horseradish peroxidase. We found labeled axons only in the nucleus of the tractus solitarius; in particular, we found strong projections to the following ipsilateral subnuclei:dorsal, interstitial, and medial part of the commissural subnucleus. Moderate labeling was found in the ipsilateral medial and intermediate subnuclei and in the contralateral dorsal subnucleus and the medial region of the commissural subnucleus. We found a mean of 256 .+-. 79 (S.E.M.) labeled afferent ganglion cells in the petrosal ganglia, and no evidence of efferent neurons in the brainstrem that innervate the carotid body; conversely, about 4000 efferent neurons of the superior cervical ganglion send terminals to the ipsilateral carotid body.
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    THE CAROTID-SINUS CONNECTIONS - A WGA-HRP STUDY IN THE CAT
    (1988) TORREALBA, F; CLAPS, A
    The neural connections of the carotid sinus were studied by administration of horseradish peroxidase or a lectin conjugate to the adventitia of the carotid sinus of cats. The carotid sinus afferents project exclusively to the nucleus of the tractus solitarius (NTS). Rostral to the obex the projection is mainly ipsilateral with a strong contralateral component caudal to the obex. The carotid sinus projects to several NTS territories that do not receive afferents from the carotid body chemoreceptors; they are: the dorsolateral, the lateral extension of the commissural, the caudal intermediate, the ventrolateral and the gelatinosus subnuclei. In addition the carotid sinus central representation includes territories occupied also by carotid body terminals; dorsal, interstitial, rostral intermediate, medial and the medial part of commissural subnuclei (see previous paper). Labeled cell bodies were found in the petrosal (216 .+-. 37, mean .+-. S.E.M.) nodose (825 .+-. 434) and superior cervical ganglia (3583 .+-. 1227) demonstrating the sympathetic efferent innervation of the carotid sinus and a dual sensory innervation via both the glossopharyngeal and vagus nerves.
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    THE VAGAL CONNECTION OF THE CAROTID-SINUS
    (1988) TORREALBA, F; CLAPS, A
    We applied wheat germ agglutinin-horseradish peroxidase (WGA-HRP) to the adventitia of the left carotid sinus of cats after tying the glossopharyngeal and the carotid sinus nerves. Forty-five to 255 neurons were labeled in the rostral pole of the nodose ganglion, through the pharyngeal branch of the vagus nerve. Transganglionic label was present only in the ipsilateral dorsal and medial subnuclei of the nucleus tractus solitarii at levels nearly rostral to the area postrema. These findings show the existence of a novel pathway from the carotid sinus, projecting via the vagus nerve, to the nucleus tractus solitarii.