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1.
Cell Tissue Res ; 326(3): 771-86, 2006 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-16788834

RESUMO

The subcommissural organ (SCO) is an ependymal differentiation located in the dorsal midline of the caudal diencephalon under the posterior commissure. SCO cells synthesize and release glycoproteins into the cerebrospinal fluid (CSF) forming a threadlike structure known as Reissner's fiber (RF), which runs caudally along the ventricular cavities and the central canal of the spinal cord. Numerous monoclonal antibodies have been raised against bovine RF and the secretory material of the SCO. For this study, we selected the 4F7 monoclonal antibody based on its cross-reactivity with chick embryo SCO glycoproteins in vivo. E4 chick embryos were injected with 4F7 hybridoma cells or with the purified monoclonal antibody into the ventricular cavity of the optic tectum. The hybridoma cells survived, synthesized and released antibody into the CSF for at least 13 days after the injection. E5 embryos injected with 4F7 antibody displayed precipitates in the CSF comprising both the monoclonal antibody and anti-RF-positive material. Such aggregates were never observed in control embryos injected with other monoclonal antibodies used as controls. Western blot analysis of CSF from E4-E6 embryos revealed several immunoreactive bands to anti-RF (AFRU) antibody. We also found AFRU-positive material bound to the apical surface of the choroid plexus primordia in E5 embryos. These and other ultrastructural evidence suggest the existence of soluble SCO-related molecules in the CSF of early chick embryos.


Assuntos
Anticorpos Monoclonais/administração & dosagem , Anticorpos Monoclonais/líquido cefalorraquidiano , Ventrículos Cerebrais/anatomia & histologia , Líquido Cefalorraquidiano/imunologia , Órgão Subcomissural/imunologia , Animais , Anticorpos Monoclonais/imunologia , Bovinos , Células Cultivadas , Ventrículos Cerebrais/embriologia , Ventrículos Cerebrais/ultraestrutura , Líquido Cefalorraquidiano/química , Embrião de Galinha , Reações Cruzadas , Embrião não Mamífero , Técnica Indireta de Fluorescência para Anticorpo , Corantes Fluorescentes , Histocitoquímica , Hibridomas/citologia , Hibridomas/metabolismo , Imuno-Histoquímica , Solubilidade , Órgão Subcomissural/ultraestrutura , Colículos Superiores/anatomia & histologia , Colículos Superiores/embriologia , Colículos Superiores/ultraestrutura , Fatores de Tempo
2.
Cell Tissue Res ; 321(3): 429-41, 2005 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-16001264

RESUMO

Reissner's fiber (RF) is a threadlike structure present in the third and fourth ventricles and in the central canal of the spinal cord. RF develops by the assembly of glycoproteins released into the cerebrospinal fluid (CSF) by the subcommissural organ (SCO). SCO cells differentiate early during embryonic development. In chick embryos, the release into the CSF starts at embryonic day 7 (E7). However, RF does not form until E11, suggesting that a factor other than release is required for RF formation. The aim of the present investigation was to establish whether the factor(s) triggering RF formation is (are) intrinsic or extrinsic to the SCO itself. For this purpose, SCO explants from E13 chick embryos (a stage at which RF has formed) were grafted at two different developmental stages. After grafting, host embryos were allowed to survive for 6-7 days, reaching E 9 (group 1) and E13 (group 2). In experimental group 1, the secretion released by the grafted SCOs never formed a RF; instead, it aggregated as a flocculent material. In experimental group 2, grafted SCO explants were able to develop an RF-like structure, similar to a control RF. These results suggest that the factor triggering RF formation is not present in the SCO itself, since E13 SCO secretion forms an RF in E13 brains but never develops RF-like structures when placed in earlier developmental environments. Furthermore, the glycoproteins released by implanted SCOs bind specifically to several structures: the apical portion of the mesencephalic floor plate and the choroid plexus of the third and fourth ventricles.


Assuntos
Ventrículos Cerebrais/anatomia & histologia , Medula Espinal/anatomia & histologia , Órgão Subcomissural , Animais , Ventrículos Cerebrais/embriologia , Embrião de Galinha , Glicoproteínas/líquido cefalorraquidiano , Imuno-Histoquímica , Ligação Proteica , Medula Espinal/embriologia , Órgão Subcomissural/anatomia & histologia , Órgão Subcomissural/embriologia , Órgão Subcomissural/metabolismo , Órgão Subcomissural/transplante , Transplante Homólogo
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