Ontogeny of the carotid body and glomus cells distributed in the wall of the common carotid artery and its branches in the chicken

Comparative morphological and molecular studies on the oxygen-chemoreceptive cells in the carotid body and fish gills

Oxygen-chemoreceptive cells play critical roles for the respiration control. This review summarizes the chemoreceptive cells in the carotid body and fish gills from a morphological and molecular perspective. The cells synthesize and secrete biogenic amines, neuropeptides, and neuroproteins and also express many signaling molecules and transcription factors. In mammals, birds, reptiles, and amphibians, the carotid body primordium is consistently formed in the wall of the third arch artery which gives rise to the common carotid artery and the basal portion of the internal carotid artery. Consequently, the carotid body is located in the carotid bifurcation region, except birds in which the organ is situated at the lateral side of the common carotid artery. The carotid body receives branches of the cranial nerves IX and/or X dependent on the location of the organ. The glomus cell progenitors in mammals and birds are derived from the neighboring ganglion, i.e., the superior cervical sympathetic ganglion and the nodose ganglion, respectively, and immigrate into the carotid body primordium, constituting a solid cell cluster. In other animal species, the glomus cells are dispersed singly or forming small cell groups in intervascular stroma of the carotid body. In fishes, the neuroepithelial cells, corresponding to the glomus cells, are distributed in the gill filaments and lamellae. All oxygen-chemoreceptive cells sensitively respond to acute or chronic hypoxia, exhibiting degranulation, hypertrophy, hyperplasia, and upregulated expression of many genes.

Striking parallels between carotid body glomus cell and adrenal chromaffin cell development

Carotid body glomus cells mediate essential reflex responses to arterial blood hypoxia. They are dopaminergic and secrete growth factors that support dopaminergic neurons, making the carotid body a potential source of patient-specific cells for Parkinson's disease therapy. Like adrenal chromaffin cells, which are also hypoxia-sensitive, glomus cells are neural crest-derived and require the transcription factors Ascl1 and Phox2b; otherwise, their development is little understood at the molecular level. Here, analysis in chicken and mouse reveals further striking molecular parallels, though also some differences, between glomus and adrenal chromaffin cell development. Moreover, histology has long suggested that glomus cell precursors are ‘émigrés’ from neighbouring ganglia/nerves, while multipotent nerve-associated glial cells are now known to make a significant contribution to the adrenal chromaffin cell population in the mouse. We present conditional genetic lineage-tracing data from mice supporting the hypothesis that progenitors expressing the glial marker proteolipid protein 1, presumably located in adjacent ganglia/nerves, also contribute to glomus cells. Finally, we resolve a paradox for the ‘émigré’ hypothesis in the chicken - where the nearest ganglion to the carotid body is the nodose, in which the satellite glia are neural crest-derived, but the neurons are almost entirely placode-derived - by fate-mapping putative nodose neuronal 'émigrés' to the neural crest.

•

Glomus cell precursors express the neuron-specific marker Elavl3/4 (HuC/D).

•

Developing glomus cells express multiple ‘sympathoadrenal' genes.

•

Glomus cell development requires Hand2 and Sox4/11, but not Ret or Tfap2b.

•

Multipotent progenitors with a glial phenotype contribute to glomus cells.

•

Fate-mapping resolves a paradox for the ganglionic 'émigré' hypothesis in birds.

Comparative embryology of the carotid body

Vertebrate carotid bodies and related structures (branchial arch oxygen chemoreceptors in fishes, carotid labyrinth in amphibians, chemoreceptors in the wall of the common carotid and its branches in birds) develop in embryos when neural crest cells, blood vessels, and nerve fibers from sympathetic and cranial nerve ganglia invade mesenchymal primordia in the wall of the 3rd branchial arch. This review focuses on literature published since the 1970s investigating similarities and differences in the embryological development of 3rd arch oxygen chemoreceptors, especially between mammals and birds, but also considering reptiles, amphibians and fishes.

Trophic factors in the carotid body

The aim of the present study is to provide a review of the expression and action of trophic factors in the carotid body. In glomic type I cells, the following factors have been identified: brain-derived neurotrophic factor, glial cell line-derived neurotrophic factor, artemin, ciliary neurotrophic factor, insulin-like growth factors-I and -II, basic fibroblast growth factor, epidermal growth factor, transforming growth factor-alpha and -beta1, interleukin-1beta and -6, tumour necrosis factor-alpha, vascular endothelial growth factor, and endothelin-1 (ET-1). Growth factor receptors in the above cells include p75LNGFR, TrkA, TrkB, RET, GDNF family receptors alpha1-3, gp130, IL-6Ralpha, EGFR, FGFR1, IL1-RI, TNF-RI, VEGFR-1 and -2, ETA and ETB receptors, and PDGFR-alpha. Differential local expression of growth factors and corresponding receptors plays a role in pre- and postnatal development of the carotid body. Their local actions contribute toward producing the morphologic and molecular changes associated with chronic hypoxia and/or hypertension, such as cellular hyperplasia, extracellular matrix expansion, changes in channel densities, and neurotransmitter patterns. Neurotrophic factor production is also considered to play a key role in the therapeutic effects of intracerebral carotid body grafts in Parkinson's disease. Future research should also focus on trophic actions on carotid body type I cells by peptide neuromodulators, which are known to be present in the carotid body and to show trophic effects on other cell populations, that is, angiotensin II, adrenomedullin, bombesin, calcitonin, calcitonin gene-related peptide, cholecystokinin, erythropoietin, galanin, opioids, pituitary adenylate cyclase-activating polypeptide, atrial natriuretic peptide, somatostatin, tachykinins, neuropeptide Y, neurotensin, and vasoactive intestinal peptide.

Innervation of the carotid body: Immunohistochemical, denervation, and retrograde tracing studies

This review presents information about multiple neurochemical substances in the carotid body. Nerve fibers around blood vessels and glomus cells within the chemoreceptive organ contain immunoreactivities (IR) for tyrosine hydroxylase (TH), calcitonin gene-related peptide (CGRP), substance P (SP), galanin (GAL), vasoactive intestinal polypeptide (VIP), neuropeptide Y (NPY), calretinin (CR), calbindin D-28k (CB), parvalbumin (PV), and nitric oxide synthase (NOS). Parasympathetic neurons scattered around the carotid body contain VIP, choline acetyltransferase, and vanilloid receptor 1-like receptor. In the mammalian carotid body, transection of the carotid sinus nerve (CSN) causes the absence or decrease of CGRP-, SP-, and NOS-immunoreactive (IR) nerve fibers, whereas all NPY-IR nerve fibers disappear after removal of the superior cervical ganglion. Most VIP-IR nerve fibers disappear but a few persist after sympathetic ganglionectomy. In addition, the CSN transection appears to cause the acquisition of GAL-IR in originally immunonegative glomus cells and nerve fibers within the rat carotid body. On the other hand, 4%, 25%, 17%, and less than 1% of petrosal neurons retrogradely labeled from the rat CSN contain TH-, CGRP-, SP-, and VIP-IR, respectively. In the chicken carotid body, many CGRP- and SP-IR nerve fibers disappear after vagus nerve transection or nodose ganglionectomy. GAL-, NPY-, and VIP-IR nerve fibers mostly disappear after removal of the 14th cervical ganglion of the sympathetic trunk. The origin and functional significance of the various neurochemical substances present in the carotid body is discussed.

Carotid body and glomus cells distributed in the wall of the common carotid artery in the bird

In the bird the carotid body is located between the distal (nodose) ganglion of the vagus nerve and the recurrent laryngeal nerve at the beginning of the common carotid artery, that is, the organ is located at the cervicothoracic border. The chicken carotid body receives numerous branches from the vagus and the recurrent laryngeal nerves. In addition, dense networks of the peptidergic nerve fibers immunoreactive for substance P, calcitonin gene-related peptide (CGRP), vasoactive intestinal peptide (VIP), galanin, and neuropeptide Y (NPY) are distributed in and around the carotid body parenchyma. The substance P- and CGRP-immunoreactive fibers are derived from both the superior and inferior ganglia of the vagus nerve. The VIP-, galanin-, and NPY-immunoreactive fibers originate from the 14th cervical ganglion of the sympathetic trunk. The endocrine organs including the thyroid gland, parathyroid glands, carotid body, and ultimobranchial gland are situated as a continuous series along the common carotid artery. The organs are supplied with arteries arising as one trunk from the common carotid artery. Glomus cells are widely distributed not only in the carotid body but also in the wall of the common carotid artery and around the common trunk and its branches. The glomus cells of the chicken carotid body exhibit intense immunoreactivity for serotonin, tyrosine hydroxylase, and chromogranin A. The cells located in the wall of the common carotid artery further express NPY mRNA and peptide. In the chickens exposed to isocapnic hypoxia for 35 days, 3-4-fold increase of the carotid body volume is induced and the carotid body glomus cells show enhanced synthetic and secretory activities. On the other hand, the cells in the wall of the common carotid artery display little changes after the long-term hypoxia, having different functions from the carotid body. The carotid body rudiment is formed in the lateral wall of the third branchial artery. The neural cells immunoreactive for TuJ1, PGP 9.5, and HNK-1, which are continuous with the inferior vagal (nodose) ganglion, first surround and then invade both the carotid body rudiment and the other portions of the third branchial artery, becoming glomus cells.

Ontogeny of galanin-immunoreactive elements in chicken embryo autonomic nervous system

To elucidate the main ontogenetic steps of galanin immunoreactivity within the extrinsic nerve supply of the alimentary tract, we undertook an immunohistochemical study of chicken embryo specimens. Fluorescence and streptavidin-biotin-peroxidase protocols were combined, using a galanin polyclonal antiserum, on transverse serial sections obtained from chicken embryos from embryonic Day 3 (E3) to hatching, and from 9-day-old newborn chicks. Galanin-immunoreactive cells were first detected at E3.5 within the pharyngeal pouch region, the nodose ganglion, the primary sympathetic chain, primitive splanchnic branches and the caudal portion of the Remak ganglion. At E5.5 galanin-immunoreactive cells and fibers appeared in the secondary (paravertebral) sympathetic chain, splanchnic nerves, peri- and preaortic plexuses, adrenal gland anlage and visceral nerves. Galanin-immunoreactive cells also lay scattered along the vagus nerve, and in the intermediate zone of the thoracolumbar spinal cord. At E18, galanin-immunoreactive cells and fibers were found along the entire Remak ganglion and around the gastrointestinal blood vessels. In post-hatching-9-day old chicks, the para- and prevertebral ganglia, but not the intermediate zone of the spinal cord, contained galanin-immunoreactive cells. Data indicate the presence of a consistent "galaninergic" nerve system supplying the chick embryonal gut wall. Whether this system has growth or differentiating role remains to be demonstrated. Its presence and distribution pattern in the later stages clearly support its well known role as a visceral neuromodulator of gut function.

Changes in the expression of neuropeptide Y (NPY) during maturation of human sympathetic ganglionic neurons: correlations with tyrosine hydroxylase immunoreactivity

Developmental patterns of neuropeptide Y (NPY) and tyrosine hydroxylase (TH)-immunoreactivities (IR) were investigated using the method of indirect immunohistochemistry in the stellate and thoracic sympathetic ganglia of human neonates ranging in gestational age from 24 to 27 weeks (premature group) and from 38 to 41 weeks (mature group). In the paravertebral ganglia of premature neonates a small (up to 7%) population of NPY-IR nerve cells was revealed. With the gestational age increase (a mature group), a marked elevation of the number of NPY-IR ganglionic neurons (up to 41%) was noted. In contrast, in the sympathetic ganglia of premature neonates almost all the neurons were tyrosine hydroxylase immunoreactive and any change in pattern during maturation was insignificant. The results demonstrate an age-related increase of neuropeptide Y-immunoreactivity in human paravertebral ganglia during maturation, and suggest that peptidergic co-transmission arises later in development than do the classical autonomic messengers. Adaptability of the fetus to a new external environment at birth demands a qualitatively new activity level of the autonomic nervous system, and this is provided side by side with the classical messengers noradrenaline and acetylcholine by the co-transmitter and modulating role of the neuropeptides. The appearance of neuropeptide Y in the principal sympathetic ganglionic neurons defines not only a qualitatively new level in the functional regulation of target organs at birth, but serves as an index of neonatal maturity.

Different effects of prolonged isocapnic hypoxia on the carotid body and the glomus cells in the wall of the common carotid artery of the chicken

In the chicken, glomus cells are widely distributed not only in the carotid body but also in the wall of the common carotid artery and around each artery arising from the common carotid artery. Effects of chronic isocapnic hypoxia on the chicken carotid body and the glomus cells in and around the arteries were examined by immunohistochemistry and electron microscopy. In chickens exposed to isocapnic hypoxia for 35 days, three- to four-fold increase of the carotid body volume was induced. Immunoreactivity for tyrosine hydroxylase of glomus cells almost completely disappeared. Dense networks of TuJ1-immunoreactive nerve fibers were unchanged, whereas peptidergic nerve fibers, i.e., substance P-, calcitonin gene-related peptide-, vasoactive intestinal peptide-, galanin- and neuropeptide Y-immunoreactive fibers, were decreased in and around the carotid body. At the electron microscopic level, increased secretory activity of the glomus cells was verified. Mature dense-cored vesicles were markedly decreased, although prosecretory granules were numerous around Golgi complexes. Many immature glomus cells filled with rough endoplasmic reticulum and free ribosomes, also appeared in the carotid bodies of hypoxic chickens. In contrast to the carotid body, the glomus cells located in the wall of the common carotid artery revealed no changes after long-term hypoxia. The cells in the hypoxic chickens, as well as normal controls, expressed intense immunoreactivity for neuropeptide Y, serotonin and chromogranin A. Furthermore, a large number of dense-cored vesicles were distributed throughout the cytoplasm. The glomus cells around each artery arising from the common carotid artery were affected by hypoxia, although the degree of their response to hypoxia varied depending on the locations.

Distribution of galanin-immunoreactive nerve fibers in the carotid labyrinth of the bullfrog, Rana catesbeiana: Comparison with substance P-immunoreactive fibers

Immunoreactivity of galanin (GAL) was detected in the nerve fibers distributed within the intervascular stroma of the bullfrog carotid labyrinth. GAL-immunoreactive fibers are numerous, and some are close to the sinusoidal plexus. Most GAL fibers appear as thin processes with some varicosities. A combination of indirect double immunofluorescence labelling and image processing clearly demonstrated that the distribution pattern of GAL fibers is different from that of SP fibers. This indicates that GAL and SP do not coexist in the same nerve fibers. The role of GAL fibers may be different from that of previously reported neuropeptides (substance P, calcitonin gene-related peptide, vasoactive intestinal polypeptide, neuropeptide Y, and others) as a neuromodulator in controlling vascular tone of the labyrinth.

Innervation of the chicken parathyroid glands: immunohistochemical study with the TuJ1, galanin, VIP, substance P, CGRP and tyrosine hydroxylase antibodies

The innervation of the chicken parathyroid glands was studied by immunohistochemistry using various antibodies. The parathyroid glands, as well as the carotid body and ultimobranchial gland, received branches originating from the vagus nerve. Numerous nerve fibers immunolabeled with the monoclonal antibody (TuJ1) against neuron-specific class III beta-tubulin isotype were found in the connective tissue capsule and septa penetrating into the parathyroid parenchyma. They were also prominent in the wall of blood vessels. Peptidergic nerve fibers immunoreactive for galanin, vasoactive intestinal polypeptide (VIP), substance P and calcitonin gene-related peptide (CGRP) were densely distributed in the capsule, septa and blood vessel walls of the parathyroid glands. In addition, some TuJ1-, substance P- and CGRP-immunoreactive fibers were detected in close association with the parenchymal cells of parathyroid glands. Tyrosine hydroxylase-immunoreactive fibers were concentrated around blood vessels and also in connective tissue stroma.

Accessory carotid body within the parathyroid gland III of the chicken

In the chicken, the cranial and caudal parathyroid glands (parathyroid gland III and IV), which are connected to each other, are located adjacent to the carotid body. In the present study, we found that a mass of glomus cells surrounded by a thick layer of connective tissue was frequently distributed within the parathyroid gland III. The glomus cells in the parathyroid III, as well as those of the carotid body, expressed intense immunoreactivity for serotonin, chromogranin A, and tyrosine hydroxylase but no immunoreactivity for neuropeptide Y. The cells possessed long cytoplasmic processes containing dense-cored vesicles of 70-220 nm in diameter, and were in close association with sustentacular cells. In and around the glomus cell clusters of the parathyroid III, dense networks of varicose fibers showed immunostaining with the monoclonal antibody TuJ1 to a neuron-specific class III beta-tubulin isotype, c beta 4. Furthermore, the distribution was also detected of numerous galanin-, vasoactive intestinal peptide (VIP)-, substance P-, and calcitonin gene-related peptide (CGRP)-immunoreactive fibers.

Glomus cell differentiation in the carotid body region of chick embryos studied by neuron-specific class III beta-tubulin isotype and Leu-7 monoclonal antibodies

Development of the carotid body and the glomus cell groups in the wall of the common carotid artery and its branches was examined in chickens at various developmental stages by immunohistochemistry using three different monoclonal antibodies, i.e., anti-neuron-specific class III beta-tubulin isotype (TuJ1), anti-rat brain beta-tubulin, and anti-Leu-7 (HNK-1) antibodies. All the antibodies reacted with neurons. The carotid body anlage was first discerned at 6 days of incubation at the lateral portion of the third branchial artery. The cells and nerve fibers immunoreactive for TuJ1, brain beta-tubulin and Leu-7, which were connected with the distal ganglion of the vagus nerve, were found around the carotid body anlage at this stage. Within the carotid body anlage, no immunoreactivity yet appeared. The immunoreactive cells were accumulated around the carotid body anlage until 8 days of incubation. From 9 days of incubation, the immunoreactive cells continuing with the distal vagal ganglion began to enter into the carotid body anlage and also dispersed widely along the common carotid artery and its branches, giving rise to the glomus cells. At 12 days of incubation, a large portion of the carotid body was occupied by the immunoreactive cells. Thus, the present study evidences that the glomus cells in the carotid body and around the arteries are emigrés that arrive in each residential place from the distal vagal ganglion. Immunoreactivity for TuJ1, brain beta-tubulin, and Leu-7 in the glomus cells started to decrease at late stages of embryonic development. After hatching, no TuJ1-immunoreactive cells were detected in the carotid body region.

Electron microscopic study on the development of the carotid body and glomus cell groups distributed in the wall of the common carotid artery and its branches in the chicken

Development of the carotid body and the glomus cell groups in the wall of the common carotid artery and its branches was studied in chickens at various developmental stages by electron microscopy. At 8 days of incubation, the carotid body anlage consisted of mesenchyme-like cells, whereas the clusters of epithelial cells, which occasionally contained a few dense-cored vesicles and were accompanied by unmyelinated nerve fibers, were located in the region surrounding the carotid body anlage and in the wall of the common carotid artery. Subsequently, the granule-containing cells together with nerve fibers were detected in the periphery of the carotid body anlage. At 12 days of incubation, a large number of granule-containing cells (glomus cells) were dispersed throughout the carotid body parenchyma and were also widely distributed along the common carotid artery and its branches. The cells frequently extended long cytoplasmic processes that made contact with other glomus cells and nerve fibers. Synaptic junctions which showed desmosome-like thickening of pre- and postsynaptic membranes and accumulations of small clear vesicles (around 50 nm in diameter) were first detected along the contact between the long axons and glomus cells at 12 days of incubation. In the wall of the common carotid artery, interdigitations between the cytoplasmic processes of glomus cells and smooth muscle cells began to form. Sustentacular cells investing partly the glomus cells were also discerned both in the carotid body and around the arteries at this stage. At 14 days of incubation, the glomus cells expressed most of the characteristics of the mature cells, and the synaptic junctions displaying afferent morphology appeared; the secretory granules of glomus cells were accumulated near and attached to the desmosome-like thickening of apposed membranes.

Ontogeny of substance P-, CGRP-, and VIP-containing nerve fibers in the amphibian carotid labyrinth of the bullfrog, Rana catesbeiana. An immunohistochemical study

The ontogeny of substance P, CGRP (calcitonin gene-related peptide), and VIP (vasoactive intestinal polypeptide) containing nerve fibers in the carotid labyrinth of the bullfrog, Rana catesbeiana, was examined by the peroxidase-antiperoxidase method. The time of appearance of these three peptides was different for each. First, CGRP fibers appeared in the wall of the carotid arch and external carotid arteries, and in a thin septum between these two arteries at an early stage of larval development (stage III). At stage V, substance P immunoreactive fibers appeared, and VIP fibers were detected at the early metamorphic stage (stage XXII). Up to the completion of metamorphosis, the number of these fibers remained low. From 1 to 5 weeks after metamorphosis, substance P, CGRP, and VIP fibers increased in number to varying degrees. By 8 weeks after metamorphosis, the distribution and abundance of these fibers closely resembled those of the adults. Some CGRP and VIP immunoreactive glomus cells were found at the stages immediately before and after the completion of metamorphosis. These findings suggest that substance P, CGRP, and VIP fibers during larval development and metamorphosis may be nonfunctional, and start to participate in vascular regulation only after metamorphosis. The transient CGRP and VIP in some glomus cells may be important for the development of the labyrinth, or may take part in vascular regulation through the close apposition of the glomus and smooth muscle cells (g-s connection).

Distribution and ontogeny of chromogranin A and tyrosine hydroxylase in the carotid body and glomus cells located in the wall of the common carotid artery and its branches in the chicken

Development and distribution of chromogranin A and tyrosine hydroxylase in the carotid body and glomus cells located in and around arteries were examined in chickens at various developmental stages by an immunohistochemical staining. In 9-day-old embryos, numerous cells immunoreactive for tyrosine hydroxylase were already detected in the connective tissue surrounding the carotid body. Some of these cells also showed immunoreactivity for chromogranin A. At 10 days of incubation, a few cells immunoreactive for tyrosine hydroxylase and chromogranin A were detected within the carotid body parenchyma. At 12 days of incubation, almost all glomus cells of the carotid body were intensely immunoreactive for these substances. Furthermore, numerous tyrosine hydroxylase- and chromogranin A-immunoreactive cells were observed in the wall of the common carotid artery, along the whole length of the carotid body artery, and around the roots of the inferior thyroid artery, the ascending esophageal artery and the esophagotracheobronchial artery; the cells already exhibited adult pattern of distribution at this stage of development. Thereafter, glomus cells immunoreactive for both substances gradually increased in number and in intensity of immunoreactivity with age, although the cells located in the wall of the common carotid artery lost immunoreactivity for tyrosine hydroxylase after hatching.