Cellular mechanisms involved in the stenosis and obliteration of the cerebral aqueduct of hyh mutant mice developing congenital hydrocephalus.
Two phases may be recognized in the development of congenital hydrocephalus in the hyh mutant mouse. During embryonic life the detachment of the ventral ependyma is followed by a moderate hydrocephalus. During the first postnatal week the cerebral aqueduct becomes obliterated and a severe hydrocephalus develops. The aim of the present investigation was to elucidate the cellular phenomena occurring at the site of aqueduct obliteration and the probable participation of the subcommissural organ in this process. Electron microscopy, immunocytochemistry, and lectin histochemistry were used to investigate the aqueduct of normal and hydrocephalic hyh mice from embryonic day 14 (E-14) to postnatal day 7 (PN-7). In the normal hyh mouse, the aqueduct is an irregularly shaped cavity with 3 distinct regions (rostral, middle, and caudal) lined by various types of ependyma. In the hydrocephalic mouse, these 3 regions behave differently; the rostral end becomes stenosed, the middle third dilates, and the caudal end obliterates. The findings indicate that the following sequence of events lead to hydrocephalus: 1) denudation of the ventral ependyma (embryonic life); 2) denudation of dorsal ependyma and failure of the subcommissural organ to form Reissner fiber (first postnatal week); 3) obliteration of distal end of aqueduct; and 4) severe hydrocephalus. No evidence was obtained that NCAM is involved in the detachment of ependymal cells. The process of ependymal denudation would involve alterations of the surface sialoglycoproteins of the ependymal cells and the interaction of the latter with macrophages.
Instituto de Histología y Patología, Facultad de Medicina, Universidad Austral de Chile, Valdivia, Chile.
C
C
Wagner
L F
LF
Batiz
S
S
Rodríguez
A J
AJ
Jiménez
P
P
Páez
M
M
Tomé
J M
JM
Pérez-Fígares
E M
EM
Rodríguez
D000375:Aging; D000818:Animals; D000831:Animals, Newborn; D001253:Astrocytes / Q000378:metabolism; D001921:Brain / Q000473:pathology / Q000502:physiology / Q000648:ultrastructure; D002352:Carrier Proteins / Q000378:metabolism; D015816:Cell Adhesion Molecules, Neuronal / Q000378:metabolism; D002535:Cerebral Aqueduct / Q000473:pathology* / Q000648:ultrastructure; D003251:Constriction, Pathologic / Q000150:complications; D004195:Disease Models, Animal; D004622:Embryo, Mammalian; D005314:Embryonic and Fetal Development; D004805:Ependyma / Q000378:metabolism / Q000473:pathology / Q000648:ultrastructure; D000071438:Fatty Acid-Binding Protein 7; D050556:Fatty Acid-Binding Proteins; D005260:Female; D020546:Fourth Ventricle / Q000378:metabolism / Q000648:ultrastructure; D005904:Glial Fibrillary Acidic Protein / Q000378:metabolism; D006849:Hydrocephalus / Q000134:cerebrospinal fluid* / Q000209:etiology / Q000235:genetics / Q000473:pathology*; D007150:Immunohistochemistry; D037102:Lectins / Q000378:metabolism; D008264:Macrophages / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D008818:Mice, Neurologic Mutants / Q000134:cerebrospinal fluid* / Q000196:embryology / Q000254:growth & development; D008854:Microscopy, Electron / Q000295:instrumentation / Q000379:methods; D008959:Models, Neurological; D009004:Monosaccharide Transport Proteins / Q000378:metabolism; D009419:Nerve Tissue Proteins / Q000378:metabolism; D019006:Neural Cell Adhesion Molecules / Q000378:metabolism; D011247:Pregnancy; D013194:Staining and Labeling; D013351:Subcommissural Organ / Q000378:metabolism / Q000648:ultrastructure; D020542:Third Ventricle / Q000378:metabolism / Q000648:ultrastructure; D014746:Vimentin / Q000378:metabolism
D002352:Carrier Proteins; D015816:Cell Adhesion Molecules, Neuronal; C086936:Fabp7 protein, mouse; D000071438:Fatty Acid-Binding Protein 7; D050556:Fatty Acid-Binding Proteins; D005904:Glial Fibrillary Acidic Protein; D037102:Lectins; D009004:Monosaccharide Transport Proteins; D009419:Nerve Tissue Proteins; D019006:Neural Cell Adhesion Molecules; D014746:Vimentin