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PubMed1999

On the pulpal nerve supply in primary human teeth: evidence for the innervation of primary dentine.

The presence of nerves in human tooth pulp has been recognized for over a hundred years, and the innervation of dentine for about 40 years. These observations have been made in permanent teeth. Very few studies have reported on the innervation of the primary pulp and dentine. The purpose of this study was to describe the innervation of the primary tooth pulp-dentine complex. Ten mature primary teeth (one incisor, six canines and three molars) were used. Immediately following extraction they were divided into three sections using a diamond disc and saline coolant. They were then immersion fixed in a solution of formaldehyde and picric acid dissolved in a phosphate buffer pH 7.4). The teeth were then demineralized for 1-3 weeks in formic acid. Following complete demineralization, 30 microns sections were cut on a freezing microtome. Neural tissue was stained using a specific antibody to calcitonin gene related peptide (CGRP). Sections were mounted on glass slides and examined using light microscopy. No individual nerve fibres were seen in the control sections, suggesting that the method used was specific for CGRP-containing nerve fibres. The primary teeth appeared to be well innervated. Myelinated and unmyelinated nerves were seen. There was a dense but variable subodontoblastic plexus of nerves (plexus of Raschkow) and nerve fibres were seen to leave this to travel towards the odontoblast layer. Most terminated here, but a few penetrated the odontoblast layer to enter predentine and the dentine tubules. The maximum penetration was 125 microns but most terminated within 30 microns of the dentinopulpal junction. The coronal region was more densely innervated than the root. Within the crown the cervical third was the most densely innervated region, followed by the pulp horn and the middle third. In conclusion, this study has demonstrated that mature primary tooth contains a pulp which is well innervated and has many nerve endings terminating in or near the odontoblast layer, with a small number penetrating into dentine.

Calcitonin Gene-Related Peptide↗
PubMed1999

Depletion of cutaneous peptidergic innervation in HIV-associated xerosis.

Severe xerosis occurs in approximately 20% of human immunodeficiency virus seropositive patients. Changes in cutaneous innervation have been found in various inflammatory skin diseases and in xerotic skin in familial amyloid. We have therefore carried out a quantitative examination of the cutaneous peptidergic innervation in human immunodeficiency virus-associated xerosis. Immunohistochemistry and image analysis quantitation were used to compare total cutaneous innervation (protein gene product 9.5), calcitonin gene-related peptide, substance P, and vasoactive intestinal peptide peptidergic fibers, at two sites in the skin of human immunodeficiency virus-associated xerosis patients (upper arm, n = 12; upper leg, n = 11) and site-matched seronegative controls (upper arm, n = 10; upper leg, n = 10). Measurement of lengths of fibers of each type was carried out for each subject in the epidermis and papillary dermis, and around the sweat glands. Immunostained mast cells in these areas were counted. Epidermal integrity and maturation were assessed by immunostaining for involucrin. There were significant (Mann-Whitney U test; p < 0.02) decreases in total lengths of protein gene product 9.5 fibers in both epidermis/papillary dermis and sweat gland fields; of calcitonin gene-related peptide innervation in the epidermis/papillary dermis; and of substance P innervation of the sweat glands. There were no differences in the distribution of mast cells, or in the epidermal expression of involucrin. Depletion of the calcitonin gene-related peptide innervation may affect the nutrient blood supply of the upper dermis, and the integrity and function of basal epidermis and Langerhans cells. Diminished substance P innervation of the sweat glands may affect their secretory activity. Both of these changes may be implicated in the development of xerosis.

Adult↗
PubMed1986

Expression of muscle-gene-specific isozymes of phosphorylase and creatine kinase in innervated cultured human muscle.

Isozymes of creatine kinase and glycogen phosphorylase are excellent markers of skeletal muscle maturation. In adult innervated muscle only the muscle-gene-specific isozymes are present, whereas aneurally cultured human muscle has predominantly the fetal pattern of isozymes. We have studied the isozyme pattern of human muscle cultured in monolayer and innervated by rat embryo spinal cord explants for 20-42 d. In this culture system, large groups of innervated muscle fibers close to the ventral part of the spinal cord explant continuously contracted. The contractions were reversibly blocked by 1 mM d-tubocurarine. In those innervated fibers, the total activity and the muscle-gene-specific isozymes of both enzymes increased significantly. The amount of muscle-gene-specific isozymes directly correlated with the duration of innervation. Control noninnervated muscle fibers from the same dishes as the innervated fibers remained biochemically immature. This study demonstrated that de novo innervation of human muscle cultured in monolayer exerts a time-related maturational influence that is not mediated by a diffusable neural factor.

Animals↗
PubMed2002

Distal forelimb cross-innervation effectively induces formation of corticorubral synapses.

We investigated whether cross-innervation of the distal forelimb extensor and flexor muscles effectively induced formation of corticorubral synapses in cats. The average time-to-peak of the corticorubral EPSPs in the red nucleus (RN) neurons innervating cervicothoracic segments (C-cells) of animals with distal forelimb cross-innervation was significantly less than that of animals with elbow cross-innervation. These fast-rising corticorubral EPSPs were shown to be induced by newly formed synapses located on the proximal soma-dendritic membrane of RN neurons, indicating that distal forelimb cross-innervation is more effective for inducing synapse formation in C-cells than elbow cross-innervation. Thus corticorubral synapse formation after forelimb cross-innervation appears to be related to direct rubrospinal connections to distal forelimb motoneurons and of functional importance to RN neurons for performing voluntary distal forelimb movement.

Animals↗
PubMed1998

Free innervated latissimus dorsi muscle flap for reconstruction of full-thickness abdominal wall defects.

Full-thickness abdominal wall defects continue to be a challenge for the reconstructive surgeon. The most frequently used reconstructive techniques are transfer of a pedicled, local abdominal flap or a distant flap from the thigh region. The purpose of this paper is to present a new approach to full-thickness abdominal wall reconstruction using an innervated free latissimus dorsi musculocutaneous flap. Four patients with large full-thickness abdominal wall defects underwent reconstruction with a free innervated latissimus dorsi muscle flap. In two patients, staged abdominal wall reconstruction was performed. Primary closure was first obtained with a skin graft. During the subsequent definitive reconstruction (with an innervated free latissimus dorsi muscle flap), this skin graft was not excised. Instead, deep dermabrasion of the skin graft was performed, leaving a residual dermal layer. This layer was then covered with a free innervated latissimus dorsi muscle flap. In these two cases, there was no need for the use of a prosthetic mesh. A single stage reconstruction was performed in the other two cases. After abdominal wall sarcoma resection, Prolene mesh was placed and subsequently covered with a free innervated latissimus dorsi muscle flap. There were no free flap failures. The average time of surgery was 4 hours, 50 minutes. The average hospital stay was 14 days. No significant complications occurred except for one donor site seroma. No hernias have occurred postoperatively. The mean follow-up was 21 months. Postoperatively, electromyographic testing was performed regularly in all patients to document reinnervation of the latissimus dorsi muscle flap. With reinnervation and intensive muscle training, the transplanted latissimus dorsi muscle offers enough contractile capacity and strength to adequately replace the function of the missing abdominal wall muscles. In complicated staged reconstructions, dermabrasion of the temporary skin graft allows for the use of a residual dermal layer as a fascia-like substitute to aid in the restoration of structural integrity. The combination of the dermal layer with an innervated free latissimus dorsi muscle provides a strong, vascularized fascial repair as well as an overlying vascularized soft-tissue coverage. In conclusion, adequate functional dynamic reconstruction of full-thickness abdominal wall defects is possible using an innervated free latissimus dorsi muscle flap. The reinnervated latissimus dorsi muscle is suitable for reconstitution of the missing functional and anatomic components of complex abdominal wall defects.

Abdominal Muscles↗
PubMed1995

The nature and distribution of the innervation of human supraspinal and interspinal ligaments.

STUDY DESIGN: To use fresh, human supraspinal and interspinal ligaments and document their innervation. OBJECTIVES: To characterize the innervation of the human supraspinal and interspinal ligaments. SUMMARY OF BACKGROUND DATA: The nature and distribution of the innervation of spinal ligaments remains unknown. METHODS: Sections of spinal ligaments were labeled with a fluorescent antibody against neurofilament proteins and observed with a confocal microscope. RESULTS: The ligaments were found to be well innervated. Innervation was equally distributed along the ligament, symmetrically distributed between left and right sides, and more densely distributed in the periphery. Pacinian corpuscles were scattered randomly, close to blood vessels, whereas Ruffini corpuscles were in the periphery, close to the collagen bundles. CONCLUSIONS: Human supraspinal and interspinal ligaments are well innervated. This innervation might form the basis of neurologic feedback mechanisms for the protection and stability of the spine. These mechanisms might also be important in the development of diseases such as scoliosis.

Adult↗
PubMed2001

Sensory innervation of the dorsal portion of the lumbar intervertebral discs in rats.

STUDY DESIGN: The levels of dorsal root ganglions (DRGs) innervating the dorsal portion of the lumbar intervertebral discs from L1-L2 to L4-L5 were investigated in rats by the retrograde transport method. The pathways and functions of nerve fibers supplying the dorsal portion of the discs were investigated by denervation and immuno-histochemistry. OBJECTIVES: To investigate the sensory innervation of the dorsal portion of the lumbar intervertebral discs in rats. SUMMARY OF BACKGROUND DATA: The dorsal portion of the L5-L6 disc has been reported to be innervated multisegmentally, and anesthetic blockade of the paravertebral sympathetic trunks and the L2 spinal nerve can relieve discogenic low back pain. However, sensory innervation of the dorsal portion of the lumbar discs at other levels has not been clarified. METHODS: A retrograde transport of Fluoro-Gold was used. We studied a nonsympathectomy group (n = 44) and a sympathectomy group (n = 50) in which paravertebral sympathetic trunks were resected from L1 to L5 levels. Using a ventral approach, Fluoro-Gold crystals were inserted into the dorsal portion of the L1-L2, L2-L3, L3-L4, and L4-L5 discs. Seven days after surgery, Fluoro-Gold-labeled neurons were counted in the bilateral dorsal root ganglions from T10 to L6. RESULTS: Fluoro-Gold-labeled neurons were distributed in dorsal root ganglions from T11 to L5 levels in the nonsympathectomy group. However, in the sympathectomy group the number of labeled neurons was less than that of the nonsympathectomy group in T11, T12, and T13 dorsal root ganglions of the L1-L2 disc group, in T12, T13, and L1 dorsal root ganglions of the L2-L3 disc group, in T12, T13, L1, and L2 dorsal root ganglions of the L3-L4 disc group, and in T12, T13, L1, and L2 dorsal root ganglions of the L4-L5 disc group. CONCLUSION: The dorsal portion of the lumbar discs from L1-L2 to L4-L5 is multisegmentally innervated by the T11 through L5 dorsal root ganglions. Sensory fibers from the upper dorsal root ganglions innervate the dorsal portion of the discs via the paravertebral sympathetic trunks, although those from the lower dorsal root ganglions innervate via the sinuvertebral nerves. Furthermore, sensory nerve fibers enter the paravertebral sympathetic trunks through the corresponding ramus communicans and reach the dorsal root ganglions via each ramus communicans at the L2 and/or more cranial levels.

Animals↗
PubMed2003

ISSLS prize winner: The innervation of the intervertebral disc: a quantitative analysis.

OBJECTIVE: The first quantitative analysis of the innervation of the lumbar intervertebral disc is presented. METHODS: A sheep model was used allowing evaluation of the whole motion segment. Four sheep spines were used. One was processed for PGP 9.5 immunofluorescence and three were processed for PGP 9.5 immunoperoxidase histochemistry. A count was made of the densities of innervation of the endplate and anulus, and these were compared. RESULTS: There is no significant difference between endplate and anulus innervation densities. The endplate innervation is concentrated centrally adjoining the nucleus. The richest area of innervation is in the perianular connective tissue. DISCUSSION: The lumbar intervertebral disc has a meager innervation. This is concentrated in the perianular connective tissue and the central endplate. Although receptor threshold is more closely related to nociceptive function than innervation density, these findings have important implications for any treatment of discogenic pain.

Animals↗
PubMed1983

The cardiac innervation of Eledone cirrhosa (Lamarck) (Mollusca: Cephalopoda).

The innervation to the cardiac organs and vessels of the octopods Eledone cirrhosa, E. moschata and Octopus vulgaris is described from vitally stained fresh material and wax-embedded sections. This innervation arises from the paired visceral nerves and includes two main peripheral ganglia (fusiform and cardiac) on each side. Several new details of the innervation are reported. Nerves supplying the lateral venae cavae arise from the ventricular nerves at the level of the ventricle. Nerve fibres run to the efferent branchial vessels from the cardiac ganglia. A small ganglion, lying on the auriculo-ventricular nerve, is described for some specimens of both species of Eledone, and is named the auricular ganglion. Commissural strands linking the right and left ventricular nerves of either side are found in Eledone, comparable to those previously described from Octopus. The detailed branching pattern of the innervation shows considerable individual variation and consistent interspecific differences. In E. cirrhosa the fine fibres innervating the inner and outer muscle layers of the auricle show distinct differences in their configuration. Innervation at the surface of the ventricular lumen and around the coronary arterial vessels shows evidence of specialization. The muscle of the branchial heart, particularly the valve leaflets at the junction of the heart and the lateral vena cava, is abundantly innervated. The observations are discussed in relation to other cephalopods and to their probable physiological significance. It is suggested that they provide evidence for a greater degree of neural influence in the control of the cardiac organs than is usually supposed and that they support the idea that the lateral venae cavae have a significant role in the generation of circulatory pressures.

Animals↗
PubMed2006

Reduced brain-derived neurotrophic factor is associated with a loss of serotonergic innervation in the hippocampus of aging mice.

Brain-derived neurotrophic factor (BDNF) regulates monoamine neuronal growth, survival and function in development and throughout adulthood. At 18 months of age, mice with constitutive reductions in BDNF expression show decreased serotonin innervation in the hippocampus compared with age-matched wildtype mice. It is not known, however, whether age-accelerated loss of serotonergic innervation in BDNF(+/-) mice occurs in other brain regions, advances beyond 18 months or is associated with alterations in other neurotransmitter systems. In this study, immunocytochemistry was used to assess serotonergic and catecholaminergic innervation in 26-month-old BDNF(+/-) mice. Age-related loss of serotonin axons in the hippocampus was potentiated in BDNF(+/-) mice compared with wildtype mice at this late age, particularly in the CA1 subregion. By contrast, aging BDNF(+/-) mice showed increased serotonin innervation of the basomedial nucleus of the amygdala. In the noradrenergic system, BDNF(+/-) mice showed reduced numbers of cell bodies and fibers in the locus coeruleus compared with age-matched wildtype mice, whereas no changes were observed in dopaminergic innervation with respect to genotype. In vivo zero net flux microdialysis in awake mice showed a significant decrease in extracellular serotonin levels in the hippocampus in BDNF(+/-) mice at 20 months of age. Thus, reduced BDNF is associated with altered serotonergic and noradrenergic innervation in aging mice and, in particular, with accelerated loss of serotonergic innervation to the hippocampus that is manifest as a decrease in basal neurotransmission.

Aging↗
PubMed1986

Adrenergic innervation and neurogenic response in large and small arteries and veins from the rat.

A combined morphological and physiological analysis of the properties of the adrenergic vasoconstrictor innervation was carried out in the splanchnic vasculature in the rat. Three generations of vessels were studied: (1) the abdominal aorta and the caval vein; (2) the superior mesenteric artery and vein; (3) 200 microns branches of the superior mesenteric artery and their parallelling veins. The adrenergic innervation was visualized by the Hillarp-Falck fluorescence technique, and by the immunohistochemical localization of immunoreactivity to tyrosine hydroxylase and dopamine-beta-hydroxylase. Determination of responses to applied noradrenaline, to transmural nerve stimulation and to direct activation of the muscle was made on ring preparations mounted in a myograph. All vessels were found to be innervated at the adventitio-medial border by noradrenergic nerves with varying density; the small arteries had the highest nerve density, the abdominal aorta was least innervated. When related to the maximal isometric response to applied noradrenaline, the maximal neurogenic response parallelled the density of the adrenergic innervation. Variations in frequency for half-maximal response among the vessels could not, however, be ascribed to innervation properties only. The constriction under isotonic conditions amounted to 20% of the initial circumference in the aorta, and to 30% in the small arteries and veins. The relation between response to applied noradrenaline and to nerve stimulation was similar for isometric and isotonic responses. In the smaller veins, a beta-receptor-mediated decline in the response to applied noradrenaline was seen. This decline was much less pronounced in neurogenic responses. The results indicate a gradation from proximal to peripheral arteries towards denser innervation and greater neurogenic responses. On the venous side only minor differences were found.

Animals↗
PubMed1972

Comparison of the hyperglycaemic and glycogenolytic responses to catecholamines with those to stimulation of the hepatic sympathetic innervation in the dog.

1. The effects of stimulation of the splanchnic innervation to the adrenal medullae, in dogs with cut hepatic nerves, were compared with those obtained previously in response to splanchnic and hepatic nerve stimulation in adrenalectomized dogs.2. Maximal stimulation of both adrenal medullae via the splanchnic innervation (20 c/s for 9 min), in dogs with cut hepatic nerves, produced closely similar hyperglycaemic and glycogenolytic responses to those obtained previously in adrenalectomized dogs with intact hepatic nerves.3. The rise in plasma glucose concentration in response to maximal stimulation of the adrenal medullae in dogs with intact hepatic nerves was found to be comparable to that which occurs in response to maximal stimulation of the hepatic sympathetic innervation alone. In contrast, the rise in haematocrit during maximal stimulation of the entire splanchnic innervation was substantially greater than that observed after removal of both adrenal glands.4. The output of adrenaline and noradrenaline from the left adrenal gland was determined during maximal stimulation of the left splanchnic nerve (20 c/s for 9 min). These results were then used to compute doses of the two amines which would reproduce the output of catecholamines from both glands under such conditions. The extent of the rise in mean plasma glucose concentration in response to these infusions was similar to that produced by maximal stimulation of both adrenal glands, but the duration of hyperglycaemia and depletion of liver glycogen were significantly less.5. Stimulation of the splanchnic innervation was found to produce an initial ;surge' in the release of catecholamines from the adrenal medullae, followed by a rapid decline in output when stimulation was continued for longer than 30 sec. Evidence was obtained which showed that this pattern of release is well suited to produce rapid mobilization of liver glycogen.6. Comparable changes in plasma glucose concentration occurred in response to stimulation of either the adrenal medullae or the sympathetic innervation to the liver at low frequency (2.0 c/s for 5 min). Stimulation of both pathways simultaneously, at the same frequency, produced smaller responses.7. Intramesenteric infusions of noradrenaline at 1.0 mug.kg(-1) min(-1) for 5 min produced comparable changes in plasma glucose concentration to those observed during stimulation of either pathway alone at low frequency. The mean plasma noradrenaline concentration of portal blood was raised by between 92 and 105 ng/ml. during these infusions.8. It is concluded that stimulation of either the splanchnic innervation to the liver, or of both adrenal medullae, at high frequency (20 c/s for 9 min) represents a supramaximal stimulus for hepatic glycogenolysis. Comparison of the responses to stimulation at low frequency (2.0 c/s for 5 min) suggests that the hepatic glycogenolytic mechanism is equally sensitive to stimulation via either route in this species.

Adrenal Glands↗
PubMed1975

Absence of polyneuronal innervation in cat extraocular muscles.

1. Polyneuronal innervation is known to occur in several types of vertebrate muscle, including mammalian muscle spindle (Gray, 1957). Previous work had led to the suggestion that the multiply innervated cat extraocular muscles were similarly polyneuronally innervated. 2. The presence of polyneuronal innervation in fibres that show propagated conduction was explored in the two muscles innervated by the abducens nerve: the lateral rectus (which contains multiply innervated fibres) and the retractor bulbus (which does not). 3. Under conditions of twitch and tetanic stimulation, the sum of individual tensions from the two nerve branches was compared with the tension elicited from the whole nerve. An analysis of variance indicated that the lateral rectus and the retractor bulbus did not differ significantly in terms of tension excess. The twitch condition yielded a small but statistically significant (P smaller than 0-01) amount of tension excess, whereas the tetanic condition did not. 4. Twitches elicited by stimulation of one branch of the abducens nerve showed slight potentiation when preceded by a tetanic stimulation to the other nerve branch. This effect could be ready differentiated from the post-tetanic potentiation elicited by applying both twitch and tetanic stimuli to the whole nerve. 5. Muscle fatigue produced by intensive stimulation of one nerve branch did not decrease the amplitude of the tetanic contraction elicited by stimulation of the other branch. In fact, instead of crossed fatigue, a small but significant (P smaller than 0-05) potentiation was observed. 6. Analysis of the results of the three tests led to the conclusion that polyneuronal innervation could not be demonstrated in cat extraocular muslce fibers that showed propagated conduction. Thus, the end-to-end muscle fibre junctions (Floyd, 1970) apparently do not transmit conducted impulses.

Abducens Nerve↗
PubMed1977

Effects of innervation on acetylcholine sensitivity of developing muscle in vitro.

1. Chick embryo skeletal muscle fibres were grown in culture. The acetylcholine (AACh) sensitivity of non-innervated fibres was compared with that of fibres innervated in vitro by chick embryo ciliary ganglion neurones. 2. The general pattern of ACh sensitivity was unchanged by innervation: ACh hot spots were superimposed on a background of uniform ACh sensitivity. 3. Quantitative comparisons revealed two differences between non-innervated and innervated fibres. First, hot spots were encountered about one third more often on innervated fibres. Secondly, about one-third of the hot spots on innervated fibres had significantly higher ACh sensitivities than the remainder, which were similar to those on control fibres. 4. Apossible explanation of these results is that nerves which form synapses induce the appearanceof end-plates which have higher ACh sensitivities than the pre-existing ACh hot spots.

Acetylcholine↗
PubMed1997

Innervation ratio and motor unit force in large muscles: a study of chronically stimulated cat medial gastrocnemius.

1. The present study uses chronic low frequency stimulation of cat medial gastrocnemius (MG) muscle to investigate the relative contribution of innervation ratio to the wide range of motor unit force in large mammalian muscles by reducing the normal variation in muscle fibre cross-sectional area and specific force. 2. Isometric force recordings from isolated and physiologically characterized motor units were made 42-240 days after stimulation. Innervation ratio, fibre area and fibre type (I, II A, II B) were determined in one glycogen-depleted motor unit per muscle. 3. After 42 days of stimulation, all motor units were non-fatigable and were classified as either slow (S) or fast-fatigue resistant (FR). Despite the absence of fast-fatigable (FF) motor units, all three muscle fibre types were present, as identified according to their myofibrillar ATPase reactivity. After 143 days, all motor units and muscle fibres were classified as type S and type I, respectively. 4. A rapid decline in muscle and motor unit force to 30% of normal values after 42 days of chronic stimulation was accounted for by a reduction in muscle fibre area. Fibre areas did not change further with longer periods of stimulation but type II fibres were converted to type I. All stimulated muscle fibres were the size of normal type I fibres; the size of the fibres within single motor units covered the full range of the muscle fibre population. 5. In long-term stimulated muscles (> 100 days) when all muscle fibres were type I and all motor units type S, only differences in innervation ratio could account for the remaining range in motor unit force. Estimates of this range from the minimum and maximum values recorded and from values of tetanic force between the 5th and 95th percentiles indicate that the range in innervation ratio in the MG muscles is at least 15-fold and may be as large as 38-fold. Enumerations of glycogen-depleted muscle fibres from single motor units were consistent with this explanation. 6. The findings provide evidence that there is a wide range of innervation ratios in large muscles, which can account for the large range in motor unit forces in the muscles. Since motor unit force and innervation ratio vary with motoneurone size, these studies provide further support that the size of the peripheral field of innervation of motoneurones is related to their size.

Animals↗
PubMed1985

Hormonal control of the anatomical specificity of motoneuron-to-muscle innervation in rats.

Motoneurons of the spinal nucleus of the bulbocavernosus innervate bulbocavernosus muscles in male rats. Adult female rats normally lack both the spinal nucleus and its target muscles. Prenatal treatment of females with testosterone propionate resulted in adults having, like males, both the spinal nucleus and its target muscles. However, prenatal treatment with dihydrotestosterone propionate preserves the muscles but not the motoneurons. This paradoxical condition might result from (i) bulbocavernosus muscles without innervation; (ii) muscles innervated by morphologically unrecognizable motoneurons; (iii) muscles innervated by a very few spinal nucleus cells, each innervating many bulbocavernosus fibers; or (iv) muscles innervated by motoneurons outside their normal anatomical locus in the spinal nucleus. The results of retrograde marker injections into the bulbocavernosus muscles of females treated with androgen refute the first three possibilities and confirm the last: the different androgen treatments result in anatomically distinct spinal motor nuclei innervating bulbocavernosus muscles.

Animals↗
PubMed1995

Timing of sympathetic innervation affects growth of myocardium in oculo.

The effects of sympathetic innervation on myocardial growth during the proliferative and hypertrophic phases of cardiac growth were examined with the use of embryonic day 12 whole hearts or ventricles cultured in the anterior eye chamber of adult rats for 8 wk. Sympathetic innervation of whole heart and ventricular grafts was prevented by removing the superior cervical ganglion 1 wk before grafting or was limited to the cellular proliferation phase of growth by superior cervical ganglionectomy after grafts had been in oculo for 4 wk. Grafts in sympathetically innervated eye chambers were significantly larger than grafts in eye chambers denervated at 4 wk and grafts in eye chambers sympathectomized 1 wk before grafting. Innervation of grafts was delayed until 5-6 wk in oculo by crushing the internal carotid nerve. Delayed innervation produced grafts that were as large as those in innervated eye chambers. Together, these experiments suggest that the effects of sympathetic innervation on myocardial growth in oculo are most apparent during the second 4 wk in oculo (i.e., during the cellular enlargement phase of growth.

Animals↗
PubMed2003

Afferent innervation patterns of the saccule in pigeons.

The innervation patterns of vestibular saccular afferents were quantitatively investigated in pigeons using biotinylated dextran amine as a neural tracer and three-dimensional computer reconstruction. Type I hair cells were found throughout a large portion of the macula, with the highest density observed in the striola. Type II hair cells were located throughout the macula, with the highest density in the extrastriola. Three classes of afferent innervation patterns were observed, including calyx, dimorph, and bouton units, with 137 afferents being anatomically reconstructed and used for quantitative comparisons. Calyx afferents were located primarily in the striola, innervated a number of type I hair cells, and had small innervation areas. Most calyx afferent terminal fields were oriented parallel to the anterior-posterior axis and the morphological polarization reversal line. Dimorph afferents were located throughout the macula, contained fewer type I hair cells in a calyceal terminal than calyx afferents and had medium sized innervation areas. Bouton afferents were restricted to the extrastriola, with multi-branching fibers and large innervation areas. Most of the dimorph and bouton afferents had innervation fields that were oriented dorso-ventrally but were parallel to the neighboring reversal line. The organizational morphology of the saccule was found to be distinctly different from that of the avian utricle or lagena otolith organs and appears to represent a receptor organ undergoing evolutionary adaptation toward sensing linear motion in terrestrial and aerial species.

Acoustic Maculae↗