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Retrograde tracing of canine posterior cricoarytenoid muscle compartments
P140
Otolaryngology Head and Neck Surgery Scientific Sessions- - Tuesday
Poster 56
Retrograde Tracing of Canine Posterior Crlcoarytenold Muscle Compartments IRA SANDERS, MD (presenter), BEI-LIAN WU, MD, and HUGH F. BILLER,MD, New York, N.Y.
The human and canine posterior cricoarytenoid muscles appear to have at least two distinct compartments, the vertical and the horizontal. These compartments have different angles of insertion onto the muscular process of the arytenoid cartilage, different proportions of fast- and slow-twitch muscle fibers, and different responses to electrical stimulation. These results suggest that these compartments have distinct functions. This study was designed to test this hypothesis by tracing these compartments back to the nucleus ambiguus to see whether their motor neurons pools are separate. Nine dogs had their posterior cricoarytenoid compartments injected with horseradish peroxidase as follows: vertical/horizontal (three dogs); vertical/both (two dogs); horizontal/both (two dogs); vertical/vertical (one dog); horizontal/horizontal (one dog). Dogs were sacrificed 4 days after injection, and the brain stems were removed, serially sectioned, stained with tetramethylbenzidine, and counterstained with neutral red. Labeled cell bodies were compared from side to side by measuring their position from the midline and from a horizontal line drawn through the floor of the fourth ventricle, which was perpendicular to the midline. Results showed that the motor neurons supplying the vertical compartment were usually located in a separate, although adjacent, location just dorsal to those supplying the horizontal compartment. In addition, the vertical motor neurons were oval, whereas the shape of the horizontal motor neurons was multipolar. These results support the possibility of different functions for these two compartments. (Supported in part by grant 01764 from the National Institute on Deafness and Other Communication Disorders.)
Poster 57
Retrograde Tracing of Motor Axons Within the Internal Superior Laryngeal Nerve BEI-LIAN WU, MD (presenter), and IRA SANDERS, MD, New York, N.Y.
In a previous study we examined l0 human internal superior laryngeal nerves (ISLN) with Karnovsky and Roots' method for acetylcholinesterase and found that 30% of the axons were stained, suggesting that these are motor n e u r o n s ( O t o l a r y n g o l Head Neck Surg 1995;113:130). In this study, we tested the hypothesis that the dog ISLN contained motor neurons by two retrograde tract-tracing experiments. In the first experiment horseradish peroxidase was injected directly into the main trunk of the ISLN in three dogs. In the second experiment horseradish peroxidase was injected into the vocal fold, and both the recurrent laryngeal and external laryngeal nerves were sectioned. After 3 days, the
August 1996
animals were euthanized by transcardiac perfusion. The brain stems were removed, serially sectioned, stained with tetramethylbenzidine, and counterstained with neutral red. All sections were examined under light- and dark-field microscopy. Results showed that all injections resulted in stained motor neuron cell bodies in the nucleus ambiguus, retrofacial nucleus, and dorsal motor nucleus of the vagus. A few labeled cell bodies appeared in the nucleus of the solitary tract in the ISLN-injection dogs. These results support the presence of significant motor innervation to the thyroarytenoid muscle from axons traveling in the ISLN. Unpublished observations from ISLN nerve lesioning experiments suggest that the ISLN innervation is mainly to muscle fibers in the false vocal cord around the ventricle. (Supported in part by grant DC 01764 from the National Institute on Deafness and Other Communication Disorders.) Poster 58
Dlstrlbutlon of Nltrerglc Neurons in the Canine Intrlnslc Laryngeal Muscles SHINOBU KOIKE, MD (presenter), YASUO HISA, MD, TOSHiYUKI UNO, MD, NOBUHISA TADAKI, MD, and HITOSHI BANBA, MD, Kyoto, Japan
The intrinsic laryngeal muscles (ILM) play an important role in such vital laryngeal functions as respiration, deglutition, and phonation. The innervation of ILM is known to be very complex, and much remains to be clarified. The existence of nitrergic neurons in ILM of the rat and dog has been demonstrated by recent studies, suggesting the participation of nitric oxide in the regulation of ILM. This study investigates the difference in distribution of nitrergic neurons between the individual intrinsic laryngeal muscles of the dog, using NADPH-diaphorase (NADPH-d) histochemistry. A previous report has shown that NADPH-d reactivity matches neuronal nitric oxide synthase immunoreactivity in canine ILM, thus detection of nitrergic neurons by NADPH-d histochemistry is reliable. Mongrel dogs were perfused through the left cardiac ventricle with 0.1 mol/L phosphate buffer with 2% paraformaldehyde under deep anesthesia, the larynx was extirpated and postfixed in the same fixative, and each intrinsic laryngeal muscle was serially sectioned on a cryostat. The sections were then histochemically stained for NADPH-d. Cells stained by NADPH-d histochemistry were found between the striated muscle fibers of ILM, most aggregated as a ganglion and some were solitary. The distribution of ganglia with NADPH-d-positive neurons within the muscles was seemingly random, many of them containing nonstaining cells besides the densely and intermediately stained positive cells. Ganglia without NADPH-d-positive cells were also observed. The number of ganglia in ILM differed between the muscles; an abundance were found in the cricothyroid and posterior cricoarytenoid muscles, a few were
Otolaryngology Head and Neck Surgery Scientific Sessions- - Tuesday
Poster 56
Retrograde Tracing of Canine Posterior Crlcoarytenold Muscle Compartments IRA SANDERS, MD (presenter), BEI-LIAN WU, MD, and HUGH F. BILLER,MD, New York, N.Y.
The human and canine posterior cricoarytenoid muscles appear to have at least two distinct compartments, the vertical and the horizontal. These compartments have different angles of insertion onto the muscular process of the arytenoid cartilage, different proportions of fast- and slow-twitch muscle fibers, and different responses to electrical stimulation. These results suggest that these compartments have distinct functions. This study was designed to test this hypothesis by tracing these compartments back to the nucleus ambiguus to see whether their motor neurons pools are separate. Nine dogs had their posterior cricoarytenoid compartments injected with horseradish peroxidase as follows: vertical/horizontal (three dogs); vertical/both (two dogs); horizontal/both (two dogs); vertical/vertical (one dog); horizontal/horizontal (one dog). Dogs were sacrificed 4 days after injection, and the brain stems were removed, serially sectioned, stained with tetramethylbenzidine, and counterstained with neutral red. Labeled cell bodies were compared from side to side by measuring their position from the midline and from a horizontal line drawn through the floor of the fourth ventricle, which was perpendicular to the midline. Results showed that the motor neurons supplying the vertical compartment were usually located in a separate, although adjacent, location just dorsal to those supplying the horizontal compartment. In addition, the vertical motor neurons were oval, whereas the shape of the horizontal motor neurons was multipolar. These results support the possibility of different functions for these two compartments. (Supported in part by grant 01764 from the National Institute on Deafness and Other Communication Disorders.)
Poster 57
Retrograde Tracing of Motor Axons Within the Internal Superior Laryngeal Nerve BEI-LIAN WU, MD (presenter), and IRA SANDERS, MD, New York, N.Y.
In a previous study we examined l0 human internal superior laryngeal nerves (ISLN) with Karnovsky and Roots' method for acetylcholinesterase and found that 30% of the axons were stained, suggesting that these are motor n e u r o n s ( O t o l a r y n g o l Head Neck Surg 1995;113:130). In this study, we tested the hypothesis that the dog ISLN contained motor neurons by two retrograde tract-tracing experiments. In the first experiment horseradish peroxidase was injected directly into the main trunk of the ISLN in three dogs. In the second experiment horseradish peroxidase was injected into the vocal fold, and both the recurrent laryngeal and external laryngeal nerves were sectioned. After 3 days, the
August 1996
animals were euthanized by transcardiac perfusion. The brain stems were removed, serially sectioned, stained with tetramethylbenzidine, and counterstained with neutral red. All sections were examined under light- and dark-field microscopy. Results showed that all injections resulted in stained motor neuron cell bodies in the nucleus ambiguus, retrofacial nucleus, and dorsal motor nucleus of the vagus. A few labeled cell bodies appeared in the nucleus of the solitary tract in the ISLN-injection dogs. These results support the presence of significant motor innervation to the thyroarytenoid muscle from axons traveling in the ISLN. Unpublished observations from ISLN nerve lesioning experiments suggest that the ISLN innervation is mainly to muscle fibers in the false vocal cord around the ventricle. (Supported in part by grant DC 01764 from the National Institute on Deafness and Other Communication Disorders.) Poster 58
Dlstrlbutlon of Nltrerglc Neurons in the Canine Intrlnslc Laryngeal Muscles SHINOBU KOIKE, MD (presenter), YASUO HISA, MD, TOSHiYUKI UNO, MD, NOBUHISA TADAKI, MD, and HITOSHI BANBA, MD, Kyoto, Japan
The intrinsic laryngeal muscles (ILM) play an important role in such vital laryngeal functions as respiration, deglutition, and phonation. The innervation of ILM is known to be very complex, and much remains to be clarified. The existence of nitrergic neurons in ILM of the rat and dog has been demonstrated by recent studies, suggesting the participation of nitric oxide in the regulation of ILM. This study investigates the difference in distribution of nitrergic neurons between the individual intrinsic laryngeal muscles of the dog, using NADPH-diaphorase (NADPH-d) histochemistry. A previous report has shown that NADPH-d reactivity matches neuronal nitric oxide synthase immunoreactivity in canine ILM, thus detection of nitrergic neurons by NADPH-d histochemistry is reliable. Mongrel dogs were perfused through the left cardiac ventricle with 0.1 mol/L phosphate buffer with 2% paraformaldehyde under deep anesthesia, the larynx was extirpated and postfixed in the same fixative, and each intrinsic laryngeal muscle was serially sectioned on a cryostat. The sections were then histochemically stained for NADPH-d. Cells stained by NADPH-d histochemistry were found between the striated muscle fibers of ILM, most aggregated as a ganglion and some were solitary. The distribution of ganglia with NADPH-d-positive neurons within the muscles was seemingly random, many of them containing nonstaining cells besides the densely and intermediately stained positive cells. Ganglia without NADPH-d-positive cells were also observed. The number of ganglia in ILM differed between the muscles; an abundance were found in the cricothyroid and posterior cricoarytenoid muscles, a few were