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PubMed2004

Somatostatin in the brain of the cave salamander, Hydromantes genei (Amphibia, Plethodontidae): immunohistochemical localization and biochemical characterization.

The distribution of somatostatin-like immunoreactivity in the brain of the cave salamander Hydromantes genei (Amphibia, Plethodontidae) was investigated by using two distinct antisera raised against somatostatin-14. Most somatostatin-positive cells were detected in the ependymal cell layer surrounding the ventricles. These cells possessed the typical morphological characteristics of tanycytes or radial glial cells. Double-labeling with an antiserum against somatostatin and a monoclonal antibody against glial fibrillary acidic protein showed that somatostatin-immunoreactive cells lining the ventricles also exhibited GFAP-like immunoreactivity. Injection of the neurotracer biocytin into the lateral ventricle revealed that neurons lining the ventricles did not contain somatostatin-like immunoreactivity. In the telencephalon, somatostatin-like immunoreactivity was confined to radial glial cells. In the diencephalon, in addition to somatostatin-immunoreactive cells in the ependyma, positive cell bodies were also found in the periventricular preoptic nucleus, the infundibular nucleus, the epiphysis, and the subcommissural organ. In the metencephalon, positive cell bodies were found in the auricula cerebelli, whereas in the rhombencephalon numerous somatostatin-immunoreactive cells were seen lining the ventricular cavity. Immunoreactive nerve fibers were observed in the hypothalamus-median eminence complex. In the pituitary, a discrete group of somatostatin-positive cells was found in the pars distalis. High-performance liquid chromatography analysis of brain extracts revealed that the immunoreactive material coeluted with somatostatin-14. The present results show that the somatostatin peptidergic system in the brain of the cave salamander has a more simple organization than those described in the brain of frog and other vertebrates. This feature is probably related to the expression of high pedomorphic characters in plethodontids. The distribution of somatostatin-like immunoreactivity suggests that, in the cave salamander, somatostatin may act as a neurotransmitter and/or neuromodulator, a central regulator of fluid homeostasis, and a hypophysiotropic neurohormone.

Animals↗
PubMed2004

Morphogenesis and regionalization of the medaka embryonic brain.

We examined the morphogenesis and regionalization of the embryonic brain of an acanthopterygian teleost, medaka (Oryzias latipes), by in situ hybridization using 14 gene probes. We compared our results with previous studies in other vertebrates, particularly zebrafish, an ostariophysan teleost. During the early development of the medaka neural rod, three initial brain vesicles arose: the anterior brain vesicle, which later developed into the telencephalon and rostral diencephalon; the intermediate brain vesicle, which later developed into the caudal diencephalon, mesencephalon, and metencephalon; and the posterior brain vesicle, which later developed into the myelencephalon. In the late neural rod, the rostral brain bent ventrally and the axis of the brain had a marked curvature at the diencephalon. In the final stage of the neural rod, ventricles began to develop, transforming the neural rod into the neural tube. In situ hybridization revealed that the brain can be divided into three longitudinal zones (dorsal, intermediate, and ventral) and many transverse subdivisions, on the basis of molecular expression patterns. The telencephalon was subdivided into two transverse domains. Our results support the basic concept of neuromeric models, including the prosomeric model, which suggests the existence of a conserved organization of all vertebrate neural tubes. Our results also show that brain development in medaka differs from that reported in other vertebrates, including zebrafish, in gene-expression patterns in the telencephalon, in brain vesicle formation, and in developmental speed. Developmental and genetic programs for brain development may be somewhat different even among teleosts.

Animals↗
PubMed1980

Early development and migration of the trigeminal motor nucleus in the chick embryo.

The development of the trigeminal motor nucleus in the chick embryo was studied using autoradiographic, cell staining, fiber staining, and axonal transport techniques. It was found that this nucleus arises very early in neurogenesis, with the first cells produced at 48 hours of incubation (stage 12), peak cell production at 50--56 hours (stage 15), and neuroblast proliferation completed by 72 hours (stage 18). As has been described in mammalian embryos, the primordial trigeminal cells move from the ventricular layer to accumulate as part of the common medial column, and later migrate in a ventrolateral direction to form the definitive lateral motor nucleus. The first identifiable component of the trigeminal system is the semilunar ganglion, which flanks the neural tube at stage 12, and sends afferents into the metencephalon by stage 13. By stage 12-13, the medial column cells are first apparent, and at stage 14, a few of these medial column cells have moved to begin formation of a lateral nucleus. At this time, a thin motor root can be seen exiting the brainstem. During subsequent stages, migratory traffic from medial to lateral regions increases, with cells frequently moving in association with fiber processes in the marginal zone. These fibers are presumed to emanate from secondary sensory, reticular, and medial column neuroblasts. By day 5, the medial column is greatly depleted and by day 6--7, the definitive lateral motor nucleus is formed. Beginning at 5 days, the dorsal motor nucleus can be detected, with cells from the lateral nucleus appearing to stream in a dorsomedial direction for its formation. Injections of horseradish peroxidase (HRP) into the mandibular process of the first visceral arch resulted in retrograde labeling of lateral nucleus cells as early as 3.5 days of incubation. In addition, migrating cells, intermediate between medial column and lateral nucleus, were similarly labeled. These observations indicate that processes of the lateral nucleus cells and those of migrating cells are well into their peripheral field at this age, but we cannot conclude that neuromuscular affiliations have been established, due to the possibility of HRP diffusion and growth cone uptake.

Animals↗
PubMed1983

Developmental relationships between trigeminal ganglia and trigeminal motoneurons in chick embryos. I. Ganglion development is necessary for motoneuron migration.

The migration and early development of trigeminal (V) motoneurons were studied in chick embryos in which two different populations of primary trigeminal sensory neurons had been removed prior to the birthdate of the V motoneurons. Ablation of mesencephalic neural crest cells, which eliminates monosynaptic sensory input, did not affect the migration, early development, or later differentiation of the V motoneurons. However, when the anlagen of the V ganglion were removed, the V motor root did not exit from the brainstem and the V motor nucleus did not develop. Although the neurons of the V ganglion do not innervate adult V motoneurons, these populations are related developmentally. In those embryos in which the V ganglion did not develop, medial column cells, which are midline, postmitotic, premigratory V motoneurons, and a few medial, elongated cells (possibly migratory) were present until days 5-6, but these cells did not complete their lateral migration to form the lateral nucleus of V. In cases where the ganglion anlagen were not completely removed, the number of postmigratory V motoneurons was positively correlated to the size of the ganglion remnant. There also was a correlation between the axial position of the postmigratory V motoneurons and the ganglion remnants. If a caudal remnant developed, only caudal V motoneurons, whose axons reached the ganglion, migrated; if a rostral remnant developed, only rostral V motoneurons, with axons reaching this remnant, migrated. Additionally, if the central axons of the ganglion remnant entered the metencephalon in either dorsal or ventral ectopic positions, the V motor nucleus was located in a corresponding aberrant position. Thus, some characteristic of the V ganglion cells appears to guide the motor axons and somas to their final brainstem position.

Animals↗
PubMed1983

Developmental relationships between trigeminal ganglia and trigeminal motoneurons in chick embryos. III. Ganglion perikarya direct motor axon growth in the periphery.

The previous study in this series demonstrated that the ingrowth of the central axons of the trigeminal (V) ganglion is prerequisite to V motor axon outgrowth and somatic translocation. In the present experiment we determined whether further interactions with V ganglion cell bodies were required by V motoneurons after the V ganglion innervates the brainstem. Soon after the ganglion axons had penetrated the brainstem they were severed, and a barrier, either permeable or impermeable, was placed between the ganglion cell bodies and the metencephalon. V motor axons grew along aberrant pathways to circumvent the impermeable barriers, many rerouting to reach the V ganglion. Only those V motor nerves which contacted the V ganglion distal to the barrier reached their target musculature in the mandible. The pattern of migration of V motoneurons was normal regardless of the V motor nerve trajectory, but the cell bodies of those axons which did not reach a muscle were not fully differentiated. When permeable barriers (Millipore filters) were implanted, the nerves followed two types of trajectories. If the pore size of the filter was small (0.45 and 0.025 microns), the V motor nerves grew identically to those observed in embryos in which impermeable barriers had been implanted. If the pore size of the filter was large (8.0 and 0.08 microns), the V motor nerve grew along its normal path directly to the barrier. Small axonal bundles from these nerves frequently grew into the filter toward the distal V ganglion. These results indicate that V motor axons preferentially grow to the V ganglion perikarya after exiting from the brainstem. Contact with the V ganglion always results in V motor nerve growth to the mandible while growth of the V motor axons to aberrant target sites only occurs when the axons fail to contact the V ganglion cells distal to the barrier.

Animals↗
PubMed1984

Organization within the cranial IX-X complex in ranid frogs: a horseradish peroxidase transport study.

Cranial nerves IX and X in frogs have been described as originating from a nuclear group referred to as the IX-X complex. We studied the central nervous system components of this complex in Rana pipiens and R. catesbiana by labeling peripheral branches of cranial nerves IX and X and identifying the central nervous system contributions of these branches. Various peripheral nerves (IX and the cardiac, gastric, pulmonary, and laryngeal branches of X) were identified and soaked in horseradish peroxidase (HRP). One to 2 weeks later, the frogs were killed and processed for HRP by the tetramethylbenzidine method. Glossopharyngeal efferents originated from a small ventrolateral cell group found at the level of IX root exit. Vagal efferents formed a single column of cells in a ventrolateral position from the level of the brainstem exist of the vagus nerve (approximately 2,000 micrometers above the obex) to 200 micrometers below the obex (values given are for an 80-g frog). This cell group was separate from and just caudal to efferent cells of the glossopharyngeal nerve. Within the vagal portion of the column, cells projecting through the gastric branch were found throughout the rostral-caudal extent of the nucleus. "Cardiac" cells tended to be more rostral than "pulmonary" cells, and both groups of cells were located in the middle of the nucleus. "Laryngeal" cells were located more caudally in the nucleus. This peripheral representation within the vagal nucleus corresponds more closely to the organization found in the mammalian nucleus ambiguus, rather than to the apparent lack of organization found in the mammalian dorsal motor nucleus. Afferents of IX and X entered slightly rostral to the ventral roots of their respective nerves and descended in two tracts. The majority entered the tractus solitarius and descended in a medial position to cervical spinal cord. A portion of the afferents from the vagus nerve crossed the midline in the lower myelencephalon just dorsal to the central canal and ascended a short distance on the contralateral side. Within the solitary tract, vagal afferents were located in a ventrolateral position as they descended to below the obex. Glossopharyngeal afferents filled the remainder of the tract. A smaller portion of afferents from both IX and X did not enter the solitary tract but descended in the spinal tract of V and the dorsolateral funiculus of the spinal cord (Lissauer's tract) to thoracic levels. Afferents of IX also formed a rostral bundle which extended in the solitary tract to the caudal metencephalon.

Animals↗
PubMed1988

Development of histamine-immunoreactive neurons in the rat brain.

This study was undertaken to reveal the cellular stores of histamine in developing rat brain and to determine the stage of development during which the histamine-immunoreactive neurons can first be detected. Rats from embryonal day 12 to postnatal day 14 were studied. The brains were fixed in 4% 1-ethyl-3(3-dimethylaminopropyl)carbodiimide and standard immunofluorescence technique was used. The first histamine-immunoreactive neurons were seen on embryonic day 13 in the border of mesencephalon and metencephalon. On embryonic day 15 immunoreactive neurons were detected in ventral mesencephalon and rhombencephalon. In caudal, tuberal, and postmammillary caudal magnocellular nuclei histamine-immunoreactive neurons were first detected on embryonic day 20 while those in the hindbrain had disappeared. Histamine-immunoreactive nerve fibers were first detected on embryonic day 15 in rhombencephalon and mesencephalon and in some areas of diencephalon including the mammillary bodies and frontal cortex. On embryonic day 18 the number of immunoreactive nerve fibers in the hindbrain had decreased considerably, but the olfactory bulb, septal and hypothalamic area, and the cerebral cortex showed immunoreaction in fibers. The density of histamine-immunoreactive fiber networks increased until postnatal day 14 when an adultlike pattern of neurons and fibers had developed. Histamine-immunoreactive neurons are present in embryonal CNS and they develop extensive projections to various brain areas.

Aging↗
PubMed1989

Distribution of proenkephalin-derived peptides in the brain of Rana esculenta.

The immunocytochemical distribution of authentic proenkephalin-containing perikarya and nerve fibers in the brain of Rana esculenta was determined with antisera directed toward different epitopes of preproenkephalin. The pattern of proenkephalinlike immunoreactivity was similar with antisera directed toward [Met5]-enkephalin, [Met5]-enkephalin-Arg6, [Met5]-enkephalin-Arg6-Phe7, [Leu5]-enkephalin, and metorphamide; however, the intensity of the labelling varied depending on the target antigen. Proenkephalin-containing perikarya were located in all major subdivisions of the brain except the metencephalon. In the telencephalon, immunoreactive perikarya were detected in the dorsal, medial, and lateral pallium; the medial septal nucleus; the dorsal and ventral striatum; and the amygdala. In the diencephalon, immunoreactive perikarya were detected in the preoptic nucleus, in the dorsal and ventral caudal hypothalamus, and in an area that appeared to be homologous to the paraventricular nucleus. In the mesencephalon, numerous immunoreactive perikarya were detected in layer 6 of the optic tectum and a few scattered perikarya were detected in layer 4 of the optic tectum. Immunoreactive perikarya also occurred in the laminar nucleus of the torus semicircularis. In the rhombencephalon, immunoreactive perikarya were detected in the obex region and the nucleus of the solitary tract. Immunoreactive fibers of varying density were observed in all major subdivisions of the brain with the densest accumulations of fibers occurring in the dorsal pallium, the lateral and medial forebrain bundles, the amygdala, the periventricular hypothalamus, the superficial region of the caudolateral brainstem, and in a tract that appeared to be homologous to the tractus solitarius. The extensive system of proenkephalin-containing perikarya and nerve fibers in the brain of an amphibian showed many similarities to the distribution of proenkephalin-containing perikarya and nerve fibers previously described for the amniote brain.

Animals↗
PubMed1991

Localization of serotonin, tyrosine hydroxylase, and leu-enkephalin immunoreactive cells in the brainstem of the horn shark, Heterodontus francisci.

In previous studies on reptiles and elasmobranchs, we determined that some reticular groups are either absent or may be displaced compared to their locations in mammals. For example, nucleus raphe dorsalis, the largest serotoninergic cell group in mammals, is not present in rays, skates, or guitarfish. In the present study, we chose heterodontid sharks, a sister group to these batoids, for an out-group comparison of this and other characters. We identified cells in the brainstem of Heterodontus francisci by use of antibodies against tyrosine hydroxylase, serotonin, or leu-enkephalin and compared the distribution of these nuclei to descriptions in mammals and other elasmobranchs. The majority of tyrosine hydroxylase-positive cells were found in the midbrain tegmentum (A8-A10) and the hypothalamus. In addition, putative A1, A2, A5, A7 (noradrenergic) groups were found in the metencephalon and myelencephalon. Serotonin-positive cells were found in raphe nuclei and scattered lateral to the raphe. We identified probable homologues to raphe pallidus, raphe obscurus, raphe magnus, and raphe centralis superior (B8) cell groups, which have been described in mammals. A cluster of cells dorsomedial to the medial longitudinal fasciculus was identified as raphe dorsalis. The distributions of leu-enkephalin and serotonin immunoreactive cells were similar to each other, but the tyrosine-hydroxylase immunoreactive cells rarely intermingle with the former two immunoreactive cell types. Other reticular groups that contained both serotonin- and leu-enkephalin-positive cells included reticularis (r.) ventralis, r. magnocellularis, r. paragigantocellularis lateralis, r. pontis caudalis, and r. pontis oralis medialis and lateralis. Thus, this shark contains many of the major brainstem raphe and catecholaminergic cell groups described for rats, but the relative distribution of the immunopositive cell groups differs in mammals and cartilaginous fish.

Animals↗
PubMed1991

Distribution of galanin-like immunoreactivity in the brain of Rana esculenta and Xenopus laevis.

The immunocytochemical distribution of galanin-containing perikarya and nerve terminals in the brain of Rana esculenta and Xenopus laevis was determined with antisera directed toward either porcine or rat galanin. The pattern of galanin-like immunoreactivity appeared to be identical with antisera directed toward either target antigen. The distribution of galanin-like immunoreactivity was similar in Rana esculenta and Xenopus laevis except for the absence of a distinct laminar distribution of immunoreactivity in the optic tectum of Xenopus laevis. Galanin-containing perikarya were located in all major subdivisions of the brain except the metencephalon. In the telencephalon, immunoreactive perikarya were detected in the pars medialis of the amygdala and the preoptic area. In the diencephalon, immunoreactive perikarya were detected in the caudal half of the suprachiasmatic nucleus, the nucleus of the periventricular organ, the ventral hypothalamus, and the median eminence. In the mesencephalon, immunoreactive perikarya were detected near the midline of the rostroventral tegmentum, in the torus semicircularis and, occasionally, in lamina A and layer 6 of the optic tectum. In the myelencephalon, labelled perikarya were detected only in the caudal half of the nucleus of the solitary tract. Immunoreactive nerve fibers of varying density were observed in all subdivisions of the brain with the densest accumulations of fibers occurring in the pars lateralis of the amygdala and the preoptic area. Dense accumulations of nerve fibers were also found in the lateral septum, the medial forebrain bundle, the periventricular region of the diencephalon, the ventral hypothalamus, the median eminence, the mesencephalic central gray, the laminar nucleus of the torus semicircularis, several laminae of the optic tectum, the interpeduncular nucleus, the isthmic nucleus, the central gray of the rhombencephalon, and the dorsolateral caudal medulla. The extensive system of galanin-containing perikarya and nerve fibers in the brain of representatives of two families of anurans showed many similarities to the distribution of galanin-containing perikarya and nerve fibers previously described for the mammalian brain.

Animals↗
PubMed1991

Neuronal differentiation and maturation in the mouse trigeminal sensory system, in vivo and in vitro.

We have isolated and characterized four monoclonal antibodies (mAbs B33, E1.9, B30, and B10) that recognize mouse trigeminal sensory neurons at specific times during development. These antibodies permit the study of neuronal differentiation, axon outgrowth, and neuronal maturation in the trigeminal sensory system. With B33, we can follow migrating neural crest and placode cells into the anlagen of the trigeminal ganglion. E1.9 immunoreactivity marks neuronal differentiation and appears in the central nervous system at embryonic day 8.5 (E8.5) and in the peripheral nervous system at E9, E1.9 and B30 show the axonal outgrowth of trigeminal sensory neurons and reveal the pioneering of the peripheral tracts by an early population of ganglionic neurons. At this stage, in the central nervous system, mesencephalic trigeminal neurons are also E1.9 and B30 positive as they migrate to their final location in the rostral metencephalon. B30 and B10 allow us to follow the maturation of these neurons. Also, in about 1% of the embryos, we identified mispositioned or misrouted trigeminal neurons. Furthermore, these biochemical markers facilitate the study of neuronal development in vitro. We find that, based on morphological and biochemical criteria, the maturation of trigeminal neurons in culture is target independent.

Animals↗
PubMed1992

Galanin immunoreactivity in the primate central nervous system.

Galanin-immunoreactive profiles were localized within the monkey and human central nervous system. In the monkey telencephalon, galanin-immunoreactive perikarya were seen within the anterior olfactory nucleus, basal forebrain, endopiriform nucleus, hippocampus, and bed nucleus of the stria terminalis. The caudate nucleus and putamen contained galanin-immunoreactive perikarya whereas the nucleus accumbens displayed only galanin-immunoreactive fibers. In the diencephalon, galanin-immunoreactive profiles were seen within the medial preoptic area, periventricular, suprachiasmatic, paraventricular, and arcuate nuclei as well as the lateral hypothalamic area. Within the thalamus, only galanin-immunoreactive fibers were seen within the midline paraventricular, reuniens, and rhomboid nuclei. In the mesencephalon, scattered galanin-immunoreactive fibers were seen in the periaquaductal gray, ventral tegmental area, and midbrain reticular formation. In the metencephalon, galanin-immunoreactive neurons were observed in the medial vestibular nucleus and nucleus prepositus. In the myelencephalon, galanin-immunoreactive perikarya were seen within the nucleus of the tractus solitarius and hypoglossal nucleus. Dense collections of galanin-immunoreactive fibers were found in the spinal descending tract of V, nucleus of the tractus solitarius, and dorsal motor nucleus of X. Galanin immunoreactivity was also observed within all circumventricular organs. Spinal anterior horn neurons expressed galanin immunoreactivity, and immunopositive fibers were seen within the tract of Lissauer and the substantia gelatinosa. Although the distribution of galanin immunoreactivity was generally similar between monkeys and humans, there were a few striking exceptions. The human supraoptic nucleus contained galanin-immunoreactive neurons, whereas the monkey supraoptic nucleus displayed only immunopositive fibers. Similarly, galanin-immunoreactive perikarya and fibers were seen in the human locus coeruleus and subcoeruleus, whereas in monkeys these regions contained only fibers. These data demonstrate a widespread distribution of galanin-containing profiles in primates, suggesting that galanin may modulate cognitive, sensory, motor, and autonomic processes.

Aging↗
PubMed1991

Distinct functions for thyroid hormone receptors alpha and beta in brain development indicated by differential expression of receptor genes.

Thyroid hormones are essential for correct brain development, and since vertebrates express two thyroid hormone receptor genes (TR alpha and beta), we investigated TR gene expression during chick brain ontogenesis. In situ hybridization analyses showed that TR alpha mRNA was widely expressed from early embryonic stages, whereas TR beta was sharply induced after embryonic day 19 (E19), coinciding with the known hormone-sensitive period. Differential expression of TR mRNAs was striking in the cerebellum: TR beta mRNA was induced in white matter and granule cells after the migratory phase, suggesting a main TR beta function in late, hormone-dependent glial and neuronal maturation. In contrast, TR alpha mRNA was expressed in the earlier proliferating and migrating granule cells, and in the more mature granular and Purkinje cell layers after hatching, indicating a role for TR alpha in both immature and mature neural cells. Surprisingly, both TR genes were expressed in early cerebellar outgrowth at E9, before known hormone requirements, with TR beta mRNA restricted to the ventricular epithelium of the metencephalon and TR alpha expressed in migrating cells and the early granular layer. The results implicate TRs with distinct functions in the early embryonic brain as well as in the late phase of hormone requirement.

Animals↗
PubMed1986

Androgen and estrogen receptors in adult zebra finch brain.

Androgens and estrogens have been implicated in the activation of a variety of sexually-dimorphic, hormone-dependent behaviors in the adult zebra finch. In the present report, several biochemical characteristics of two putative sex steroid receptors, androgen- and estrogen-binding activities, were determined by DNA-cellulose chromatography in brain tissues from these birds. High-affinity, limited-capacity receptors for androgens and estrogens were found in cytosolic extracts of telencephalon, diencephalon-mesencephalon, and metencephalon-myelencephalon from adult male and female zebra finches. Androgen-binding activity reproducibly adhered to DNA-cellulose and was eluted within the 110-150 mM NaCl region of a linear salt concentration gradient. Estrogen receptors adhered to DNA-cellulose and exhibited elution maxima between 170 mM and 210 mM NaCl. Collectively these data indicate that brain regions of zebra finches contain steroid receptors that are similar to those found in the brains of other vertebrates and that their biochemical properties are similar in males and females. Quantitatively, males consistently exhibited higher androgen binding than females in both anterior and posterior telencephalic areas. Females treated with estradiol immediately after hatching exhibited adult levels of androgen binding corresponding to those detected in males. Masculinization of the androgen receptor system by early steroid exposure is discussed.

Animals↗
PubMedDate not supplied

Expression of an engrailed-like gene during development of the early embryonic chick nervous system.

The engrailed gene has been identified in Drosophila as an important developmental gene involved in the control of segmentation. Here we describe the embryonic expression of a chicken gene, ChickEn (Darnell et al.: J Cell Biol 103(5):311a, 1986), which contains homology to the Drosophila engrailed gene. Northern blots of early chick embryo tissue poly(A)+ RNA resulted in hybridization to at least three bands expressed predominantly in the brain/head region when probed with ChickEn genomic fragments. Eight cDNA clones generated from embryonic day 6 (stage 29-30) chick brain poly(A)+ RNA are identical in their nucleotide sequence with the ChickEn genomic clone. In situ hybridization to sections of 4-day (stage 24) embryos indicated that ChickEn transcripts were concentrated in the posterior mesencephalon and anterior metencephalon. In cultures of chick cranial neural crest cells (eight to nine somites; stage 9) ChickEn transcripts were localized in a subset (approx. 8%) of cells examined after 2 days in culture. A mouse monoclonal antibody, inv-4D9D4, made by Coleman and Kornberg recognizes the engrailed-like homeo domain of the engrailed and invected proteins (Martin-Blanco, Coleman, and Kornberg, personal communication). Patel, Coleman, Kornberg and Goodman (unpublished) have shown that this antibody binds to the hindbrain of 2-day-old chick embryos. We have confirmed these results and shown that this antibody binds to the same region of 4-day (stage 24) chick brains that in situ hybridization showed contained ChickEn transcripts. This antibody also recognizes a homeo domain-containing ChickEn peptide expressed as a beta-galactosidase fusion protein in Drosophila cell culture. We have not detected ChickEn protein in any tissue prior to eight to nine somites (stage 9). These results delineate the major expression pattern of the ChickEn gene during early (prior to stage 30) embryonic development in the chick.

Animals↗
PubMed2004

Development of the human fetal pons: in utero ultrasonographic study.

OBJECTIVES: To examine the ultrasonographic feasibility of imaging the fetal pons and to construct a reference chart for its normal development during gestation. METHODS: A cross-sectional, prospective study on 293 healthy fetuses of low-risk pregnancies between 19 and 34 weeks was performed. The transfontanel approach, via the abdominal or vaginal routes, was used to evaluate the fetal metencephalon (pons and cerebellum). The anteroposterior diameter of the fetal pons was measured in a mid-sagittal plane. The longitudinal diameter of the cerebellar vermis was measured at the same plane and the vermis-pons ratio (VPR) was established. RESULTS: One hundred and forty-four fetuses were in vertex position. In 140 (97.2%) satisfactory visualization and measurements of the pons and cerebellar vermis were obtained. One hundred and forty-nine fetuses were breech presentations and measurements were successfully performed in 147 (98.6%). The pons anteroposterior and vermis longitudinal diameters showed a linear correlation with gestational age (GA) (r = 0.95 for both measurements; P < 0.001). The mean VPR was 1.5 (+/-0.1 SD) and did not change in the gestational interval that was considered. CONCLUSION: By using the transfontanel approach, evaluation of the fetal pons is feasible via the mid-sagittal plane. The nomograms developed and the ratio to fetal vermis provides reference data that may be helpful when evaluating anomalies of the brainstem.

Cross-Sectional Studies↗
PubMed1994

A novel NK-related mouse homeobox gene: expression in central and peripheral nervous structures during embryonic development.

We have identified three novel mouse homeobox genes that are related to the Drosophila NK gene family. Two genes without direct homologues in Drosophila were designated Nkx-5.1 and Nkx-5.2; the third gene Nkx-1.1 constitutes the mouse homologue to NK1.Nkx-5.1 and Nkx-5.2 are closely linked on mouse chromosome 7, whereas Nkx-1.1 is located on a different chromosome. Here, we report the spatiotemporal expression pattern of Nkx-5.1 during prenatal mouse development. Nkx-5.1 gene activity begins at Embryonic Day 10.5 in the developing ear, the neural tube, and dorsal root ganglia. It continues to be active throughout prenatal life in discrete regions of the brain with an anterior border in the ventral diencephalon at the optic chiasma and expression domains in mesencephalon, metencephalon, and myelencephalon. At midgestation, Nkx-5.1 is also expressed in mesenchyme of the head and branchial arches, and in some cranial ganglia, as well as in derivatives of neural crest, such as the truncus sympathicus and myenteric ganglia. The time pattern of Nkx-5.1 expression and its confinement to primarily postmitotic cells of the central and peripheral nervous system suggest that Nkx-5.1 may play a role in the specification of neuronal cell types.

Amino Acid Sequence↗
PubMed1994

Distribution of kappa opioid receptor mRNA in adult mouse brain: an in situ hybridization histochemistry study.

The distribution of the kappa opioid receptor mRNA in adult mouse brain has been determined using the technique of in situ hybridization histochemistry. The mRNA for the kappa opioid receptor was expressed in distinct areas throughout the brain. The telencephalon showed high levels of expression in the deeper layers of the parietal and temporal cortex, olfactory tubercle, nucleus accumbens, claustrum, endopiriform nucleus, nucleus of the vertical and horizontal limb of the diagonal band, and medial and central nuclei of the amygdala. In the diencephalon, kappa opioid receptor mRNA was present in multiple medial thalamic nuclei including the centromedial, paraventricular, parafasicular, central, and peritenial nuclei, as well as in most hypothalamic nuclei including the ventromedial, periventricular, supraoptic, arcuate, and dorsomedial nuclei. The mesencephalon showed highest levels of kappa receptor mRNA in the substantia nigra pars compacta, ventral tegmental area, zona incerta, interpeduncular nucleus, superior colliculus, inferior colliculus, central grey, and the raphe nucleus. In the metencephalon, kappa opioid receptor mRNA was expressed in the parabrachial nuclei, locus coeruleus, dorsal and ventral tegmental nuclei, and the raphe pontine nuclei. The distribution of the kappa receptor mRNA closely coincides with the localization of binding sites in rat brain for [3H]U-69,593, a specific kappa 1 opioid receptor ligand. The mRNA distribution also correlates with neuroanatomical sites of actions of kappa agonists and distribution of the endogenous kappa receptor ligand dynorphin.

Animals↗