Diplomyelia: Caudal duplication of the neural tube in mice

Abstract

Diplomyelia (duplication of the neural tube or spinal cord) was studied histologically in nine cases of T/+ mouse embryos at 10-15 days of gestation. Grüneberg investigated T/+ fetuses and interpreted the extra neural tube to be notochord, but a reexamination of this material demonstrated that the interpretation is incorrect. Diplomyelia is produced in the mutations Fused, Kinky, vestigial tail, homozygous Brachyury, and t-haplotype t9 and in the new mutation, NM 529, described here.

In vivo knockdown of Brachyury results in skeletal defects and urorectal malformations resembling caudal regression syndrome

“…It has been noted that T-null mutants have an abnormal notochord in rostral regions at E8.0 (Yamaguchi et al, 1999), and inbred T þ /À embryos can have an abnormal notochord which is absent in the caudal-most region (Chesley, 1935;Cogliatti, 1986;Gruneberg, 1958). Analysis of the KD3-T model illustrates that sufficient levels of notochordal T are required for differentiation of a mature notochord structure which retains mesodermal character, as opposed to adopting a neural character.…”

Morphological Analysis of Neural Tube Defects in Non‐obese Diabetic (NOD) Mouse Embryos

“…The problem of the mesenchymal abmormalities is considered to be more quantitatively observed in the future research. Failure of closure may be related to genetic predisposition (Campbell et al, 1986;Cogliatti, 1986;Park et al, 1989), though other causes of abnormal neurulation should be considered. Abnormalities of the ependymal cells might secondarily occur as a result of the abnormal neurulation.…”

The Embryogenesis of Complex Dysraphic Malformations: A Disorder of Gastrulation?

“…The rarity of these com plex malformations has led to the suggestion that duplica tion or splitting of the neuraxis is less common in animals that it is in humans [44], Neural tube duplications have been described in several strains of laboratory mice, including the mutations Fused (Ftt/Fu), 'Rib Vertebrae', Kinky (Ki/Ki), vestigial tail (vt/ vt), the lethal t -haplotype (t''l t 9), and those with both homozygous (T/T) and heterozygous (T/ + ) mutations at the /-locus (located on chromosome 17). Many of these mutants exhibit partial doublings of both notochord and neural tube: associated vertebral anomalies, including ver tebral fusions and agenesis, have been described in several types [26]. The pathogenesis of the malformations in these mutants is unknown; a disturbance within either the prim itive streak or Hensen's node during gastrulation has been suggested by several authors [26], However, the relation ship of these mutations to human malformations is un clear: in many, the neural lube is split dorsoventrally and the malformation bears little resemblance to those seen in humans.…”

“…Many of these mutants exhibit partial doublings of both notochord and neural tube: associated vertebral anomalies, including ver tebral fusions and agenesis, have been described in several types [26]. The pathogenesis of the malformations in these mutants is unknown; a disturbance within either the prim itive streak or Hensen's node during gastrulation has been suggested by several authors [26], However, the relation ship of these mutations to human malformations is un clear: in many, the neural lube is split dorsoventrally and the malformation bears little resemblance to those seen in humans. Neither bony nor fibrocartilaginous septi of the type seen in human SCM have been described in these mutants.…”