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PubMed2000

Facial visceral motor neurons display specific rhombomere origin and axon pathfinding behavior in the chick.

In the chick embryo, facial motor neurons comprise branchiomotor and visceral motor subpopulations, which innervate branchial muscles and parasympathetic ganglia, respectively. Although facial motor neurons are known to develop within hindbrain rhombomere 4 (r4) and r5, the precise origins of branchiomotor and visceral motor neuron subpopulations are unclear. We investigated the organization and axon pathfinding of these motor neurons using axonal tracing and rhombomere transplantation in quail-chick chimeras. Our results show that a large majority of branchiomotor neurons originate in r4 but that a cohort of these neurons undergoes a caudal migration from r4 into r5. By contrast, visceral motor neurons develop exclusively in r5. We found that a striking property of facial visceral motor neurons is the ability of their axons to navigate back to appropriate ganglionic targets in the periphery after heterotopic transplantation. These results complement previous studies in which heterotopic facial branchiomotor neurons sent axons to their correct, branchial arch, target. By contrast, when trigeminal branchiomotor neurons were transplanted heterotopically, we found that they were unable to pathfind correctly, and instead projected to an inappropriate target region. Thus, facial and trigeminal motor neuron populations have different axon pathfinding characteristics.

Animals↗
PubMed2001

Generation of a novel functional neuronal circuit in Hoxa1 mutant mice.

Early organization of the vertebrate brainstem is characterized by cellular segmentation into compartments, the rhombomeres, which follow a metameric pattern of neuronal development. Expression of the homeobox genes of the Hox family precedes rhombomere formation, and analysis of mouse Hox mutations revealed that they play an important role in the establishment of rhombomere-specific neuronal patterns. However, segmentation is a transient feature, and a dramatic reconfiguration of neurons and synapses takes place during fetal and postnatal stages. Thus, it is not clear whether the early rhombomeric pattern of Hox expression has any influence on the establishment of the neuronal circuitry of the mature brainstem. The Hoxa1 gene is the earliest Hox gene expressed in the developing hindbrain. Moreover, it is rapidly downregulated. Previous analysis of mouse Hoxa1(-/-) mutants has focused on early alterations of hindbrain segmentation and patterning. Here, we show that ectopic neuronal groups in the hindbrain of Hoxa1(-/-) mice establish a supernumerary neuronal circuit that escapes apoptosis and becomes functional postnatally. This system develops from mutant rhombomere 3 (r3)-r4 levels, includes an ectopic group of progenitors with r2 identity, and integrates the rhythm-generating network controlling respiration at birth. This is the first demonstration that changes in Hox expression patterns allow the selection of novel neuronal circuits regulating vital adaptive behaviors. The implications for the evolution of brainstem neural networks are discussed.

Animals↗
PubMedDate not supplied

[Shape conservatism and shaping variability. The comparative analysis of Hydrozoa and Scyphozoa early development].

The morphogenetic pathways based on the self-organization take an important part in the early development of White Sea Cnidarians--Dynamena pumila (Hydrozoa) and Aurelia aurita (Scyphozoa). Comparative analysis of their early development revealed two patterns of embryonic spatial structure reproduced in the morphogenesis of both species in spite of the differences of morphogenetic paths. These are toroidal and bilaterally symmetrical shapes. It is possible that these shapes correspond to the equilibrium states of developing system and their stable reproduction is a result of epigenetic rather than genetic program.

Animals↗
PubMed2003

Trigeminal neuralgia associated with a primitive trigeminal artery variant: case report.

OBJECTIVE AND IMPORTANCE: A variant type of the primitive trigeminal artery (PTA) is a rare anomalous vessel that originates from the internal carotid artery and directly supplies the territory of the anteroinferior cerebellar artery and/or the superior cerebellar artery. We report a case of trigeminal neuralgia associated with this PTA variant, and we discuss the characteristics of this vessel. CLINICAL PRESENTATION: A 51-year-old woman presented with a 10-year history of left paroxysmal facial pain. Magnetic resonance angiography and cerebral angiography demonstrated that an aberrant vessel originating from the left internal carotid artery directly supplied the cerebellum, without a basilar artery anastomosis. INTERVENTION: Surgical exploration was performed via a left retrosigmoid approach. A loop of the aberrant vessel, which entered the posterior fossa through the isolated dural foramen, was compressing the trigeminal nerve. This aberrant vessel was displaced medially from the nerve with a prosthesis, with care to avoid kinking and avulsion of the perforating arteries. The patient's neuralgia resolved postoperatively. CONCLUSION: Although the PTA variant is frequently associated with intracranial aneurysms, it is extremely rare for the variant to lead to trigeminal neuralgia. During microvascular decompression surgery, surgeons should be careful to prevent injury of the perforating arteries arising from the PTA variant.

Arteries↗
PubMedDate not supplied

[Ganglioneuroma in a newborn with early inborn syphilis].

A case is reported of a retroperitoneal sympathic nodes ganglioneuroma in a newborn with classic early inborn syphilis involving practically all systems of the viscera, skin, placenta. Some peculiar morphological features of the tumour are described. Possible teratogenic and oncogenic effects of treponema pallidus on embryonal fetal structures during intrauterine development are suggested.

Fatal Outcome↗
PubMed2006

[Velocimetry of the ductus venosus in the first stage of labor].

OBJECTIVE: To assess feasibility and physiological variation of fetal ductus venosus Doppler velocimetry during the first stage of labor between uterine contractions. STUDY DESIGN: A prospective cross-sectional study including 23 healthy women with low-risk pregnancies. Maximum velocities during ventricular systole (S) and atrial contraction (A) were recorded in the ductus venosus between contractions. Pulsatility index for veins (DV PIV) and the ductus venosus index (DVI) were also calculated. SETTING: Department of Obstetrics and Gynecology, Jessenius Faculty of Medicine, Comenius University, Martin. RESULTS: Acceptable ductus venosus waveforms were acquired in 19 fetuses (83%). The mean +/- SD values of the ductus venosus index and the pulsatility index were 0.46 +/- 0.07 (95% CI: 0.42-0.49) and 0.57 +/- 0.12 (95% CI: 0.51-0.63), respectively. The mean +/- SD values of maximum velocities during ventricular systole (S) and atrial contraction (A) were 65 +/- 8 cm/s and 35 +/- 5 cm/s, respectively. CONCLUSION: Ductus venosus blood flow velocities can be assessed during labor. This calls for an extension of the detection possibilities of intrauterine fetal status and gives an idea to establish reference ranges for these circulation parameters during labor in the future.

Blood Flow Velocity↗
PubMed1992

Proteoglycan-Lb, a small dermatan sulfate proteoglycan expressed in embryonic chick epiphyseal cartilage, is structurally related to osteoinductive factor.

We have isolated cDNA clones encoding the core protein of PG-Lb, proteoglycan which has been shown to be preferentially expressed in the zone of flattened chondrocytes of the developing chick limb cartilage (Shinomura, T., Kimata, K., Oike, Y., Yano, S., and Suzuki, S. (1984) Dev. Biol. 103, 211-220). The deduced amino acid sequence from the cDNA analysis indicates the presence of consensus leucine-rich repeats which are present in other small proteoglycans, decorin, biglycan, and fibromodulin. However, the homology analysis revealed that chick PG-Lb showed a higher homology (about 50% in the region containing leucine-rich repeats) to human osteoinductive factor, OIF, rather than to the other small proteoglycans. Furthermore, 6 cysteine residues are detected in both PG-Lb and OIF with invariant relative positions. Therefore, such an evolutionarily conserved structure in the PG-Lb core protein might be involved in some important biological functions of this molecule. In close relation to the structural similarity to OIF, the unique expression of PG-Lb in the ossifying area of cartilage suggested the possible participation of this proteoglycan in osteogenic processes.

Amino Acid Sequence↗
PubMedDate not supplied

Biochemical basis of the diabetic embryopathy.

Signal transduction, phosphatidylinositol turnover and the arachidonic acid cascade appear to be a final common pathway involved in the differentiation and development of the early embryo and several embryonic organ structures. Disruption of this biochemical pathway by various agents may account for the occurrence of the diabetic embryopathy.

Animals↗
PubMed1990

[Transplantation of embryonal nerve tissues in the treatment of Parkinson disease].

The authors describe the results of experimental studies of transplants of embryonal nervous tissues of man in the brain of adult animals. Base the use of transplantation of the embryonal dopaminergic structures for the treatment of patients suffering from parkinsonism. Provide the first results of the treatment of 2 patients suffering from parkinsonism by means of transplanting parts of the medium cerebral vesicle of human embryos. The observation period amounts to 6 months.

Animals↗
PubMedDate not supplied

[Mechanical stresses as factors in the autoregulation of morphogenesis].

Since morphogenetic processes are nonlinear, feedback must be essential for their regulation. Two concepts of feedback in morphogenesis are developed: 1) inhibition by diffusing morphogenetic substances and 2) action of mechanical strain resulting from morphogenetic movements. The data on the role of mechanical strain in formation of integral structure of embryonic tissues, primary demarcation of embryonic epithelia and mesenchymal rudiments and bending of epithelial layers are presented. Evolutionary aspects of morphogenetic role of mechanical strain and its possible use in applied biotechnology are discussed.

Animals↗
PubMed1989

An immunohistochemical study of neuropeptides and neuronal cytoskeletal proteins in the neuroepithelial component of a spontaneous murine ovarian teratoma. Primitive neuroepithelium displays immunoreactivity for neuropeptides and neuron-associated beta-tubulin isotype.

Approximately one third of the female mice of the LTXBO strain develop spontaneous ovarian teratomas. These tumors contain a large neuroepithelial component, which includes primitive neural structures resembling embryonic neural tubes (medulloepithelial rosettes), ependymoblastic and ependymal rosettes, neuroblasts, mature ganglionic neurons, myelinated neurites, and astrocytes. The purpose of this study was to characterize these tumors according to the immunohistochemical location of some well-characterized trophic and regulatory neuropeptides and neurotransmitters, several neuronal-associated cytoskeletal proteins, and other proteins indicative of neuronal and glial differentiation. Medulloepithelial rosettes showed focal serotonin-like, opioid peptide-like and gamma-amino butyric acid-like immunoreactivity, and displayed immunostaining for the neuron-associated class III beta-tubulin isotype. The mature ganglion cells were also immunoreactive for these markers, and, in addition, for somatostatin, cholecystokinin, bombesin, glucagon, vasoactive intestinal peptide, and neuropeptide Y. Mature ganglion cells were also immunoreactive for proteins associated with the neuronal cytoskeleton (including microtubule-associated proteins, MAP2 and tau, and higher molecular weight phosphorylated and non-phosphorylated neurofilament subunits), neuron-specific enolase, and synaptophysin. Undifferentiated stem cells, ependymoblastic and ependymal rosettes, and astroglia all stained with a monoclonal antibody that recognizes all mammalian beta-tubulin isotypes, but did not react with antibodies to neuronal-associated cytoskeletal proteins or neuropeptides. Neuropeptide-like immunoreactivity and demonstration of the class III beta-tubulin isotype indicate early neuronal commitment in neoplastic primitive neuroepithelium. These patterns of immunoreactivity closely follow those encountered in the normal neurocytogenesis of the mammalian and avian forebrain, and increase the precision with which the early stages of progressive neuroepithelial differentiation can be analyzed in human embryonal tumors of the CNS.

Animals↗