The histogenesis of the isthmic nuclei in chick embryos (Gallus domesticus)

Vaage, Sigmund

doi:10.1007/bf00519134

Cited by 63 publications

(106 citation statements)

References 18 publications

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“…The anatomical terms for the medaka brain are in accordance with those of previous reports [Ishikawa, 1997;Ishikawa et al, 1999Ishikawa et al, , 2004Ishikawa et al, , 2007Ishikawa et al, , 2008Kage et al, 2004], and several embryological terms for the mesencephalic and cerebellar regions are in accordance with those of Palmgren [1921], Vaage [1973], Pouwels [1978] and Nguyen et al [1999].…”

Section: Anatomical Termssupporting

confidence: 76%

“…In a previous paper [Ishikawa et al, 2008], we examined gene expression patterns and morphogenesis in the early development (from the neural plate stage to the neural tube stage) of teleostean cerebellum, using the medaka (Oryzias latipes) , which is an important fish model for the studies of vertebrate developmental genetics and comparative genomics [Yamamoto, 1975;Ishikawa, 2000;Kinoshita et al, 2009]. We found that the metencephalic alar plates of both the fgf8 -positive isthmic rhombomere (irh) and the fgf8 -negative first rhombomere of Vaage [1973] (rh1) develop into the medaka cerebellum. We also found that the fgf8 -positive VC protrudes into the midbrain ventricle and the isthmic constriction shifts caudally during neural tube development.…”

Section: Introductionmentioning

confidence: 99%

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Morphogenesis of the Medaka Cerebellum, with Special Reference to the Mesencephalic Sheet, a Structure Homologous to the Rostrolateral Part of Mammalian Anterior Medullary Velum

Ishikawa¹,

Yamamoto

Yasuda³

et al. 2010

Brain Behav Evol

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We have examined cerebellar morphogenesis after neural tube stage in medaka (Oryzias latipes), a ray-finned fish, by conventional histology and immunohistochemistry using anti-proliferating cell nuclear antigen (PCNA) and anti-acetylated tubulin antibodies. Our results indicate that the medaka cerebellum is formed in 4 successive stages: (1) formation and enlargement of the cerebellar primordia; (2) rostral midline fusion of the left/right halves of the cerebellar primordia; (3) formation of the cerebellar matrix zones in the midline and caudalmost regions of the primitive cerebellum, and (4) growth and differentiation of the cerebellum. Our results also show that cerebellar morphogenesis is different from that in mammals in 3 important points: the developmental origins of the primordia, directions along which cerebellar fusion proceeds, and number, locations and duration of the cerebellar matrix zones. During the course of this study, an alar-derived membranous structure between the cerebellum and the midbrain in the adult medaka brain was identified as the structure homologous to the rostrolateral part of the mammalian anterior medullary velum. We have named this structure in the adult teleostean brains as the ‘mesencephalic sheet’. The present study indicates that there exists both conserved and divergent patterns in cerebellar morphogenesis in vertebrates.

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Section: Anatomical Termssupporting

confidence: 76%

Section: Introductionmentioning

confidence: 99%

Morphogenesis of the Medaka Cerebellum, with Special Reference to the Mesencephalic Sheet, a Structure Homologous to the Rostrolateral Part of Mammalian Anterior Medullary Velum

Ishikawa¹,

Yamamoto

Yasuda³

et al. 2010

Brain Behav Evol

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“…The IZ is conspicuous during neurogenesis of all vertebrates examined (see Palmgren, 1921;Bally-Cuif et al, 1993). According to classical neuroanatomical studies (Vaage, 1969;Vaage, 1973), it corresponds in the chick to a caudal 'mesomere' which initially encompasses half the midbrain but upon regression during development forms a narrow, neuronfree stripe at the junction with the first rhombomere. Lineage analysis in the zebrafish (A.T. and L.B.-C., unpublished) demonstrate that this is a dynamic process where the IZ progressively contributes cells to adjacent territories upon cell divisions.…”

Section: Introductionmentioning

confidence: 99%

bHLH transcription factor Her5 links patterning to regional inhibition of neurogenesis at the midbrain-hindbrain boundary

et al. 2003

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The midbrain-hindbrain (MH) domain of the vertebrate embryonic neural plate displays a stereotypical profile of neuronal differentiation, organized around a neuron-free zone (`intervening zone', IZ) at the midbrain-hindbrain boundary(MHB). The mechanisms establishing this early pattern of neurogenesis are unknown. We demonstrate that the MHB is globally refractory to neurogenesis,and that forced neurogenesis in this area interferes with the continued expression of genes defining MHB identity. We further show that expression of the zebrafish bHLH Hairy/E(spl)-related factor Her5 prefigures and then precisely delineates the IZ throughout embryonic development. Using morpholino knock-down and conditional gain-of-function assays, we demonstrate that Her5 is essential to prevent neuronal differentiation and promote cell proliferation in a medial compartment of the IZ. We identify one probable target of this activity, the zebrafish Cdk inhibitor p27Xic1. Finally, although the her5 expression domain is determined by anteroposterior patterning cues, we show Her5 does not retroactively influence MH patterning. Together, our results highlight the existence of a mechanism that actively inhibits neurogenesis at the MHB, a process that shapes MH neurogenesis into a pattern of separate neuronal clusters and might ultimately be necessary to maintain MHB integrity. Her5 appears as a partially redundant component of this inhibitory process that helps translate early axial patterning information into a distinct spatiotemporal pattern of neurogenesis and cell proliferation within the MH domain.

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“…rhombomere 1 elongates tremendously and undergoes a complex morpho genesis giving rise to the entire isthmic region of the brain. Based on differentiation and migration patterns, this region can be subdivided into two or more units, referred to here as rO and rl [28], Caudal to von Kupffer's first rhombomere five distinct segments are visible in most vertebrate embryos ( fig.2). Scanning electron micrographs show that these segments are delimited by six interneuromeric borders, the first being the demarcation between rl and r2, the sixth being the posterior demarcation of r6.…”

Section: General Pattern Of Hindbrain Segmentation In Vertebratesmentioning

confidence: 99%

Conservation of Neuroepithelial and Mesodermal Segments in the Embryonic Vertebrate Head

Gilland¹,

Baker²

1993

Cells Tissues Organs

166

148

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The organization of embryonic efferent cranial nerves is addressed here by inter-species comparison of segmentally patterned neuromeres, efferent neuronal populations and early mesodermal sources of target muscles. The segmental constancy of these three structural patterns is evaluated for elasmobranch teleost, reptile, bird and mammal embryos and compared with the segmentally restricted expression patterns of Hox genes. A conserved series of hindbrain neuroepithelial segments (rhombomeres) is present in all of these taxa. Dye-labeling experiments demonstrate that the segmental locations of efferent neurons projecting through individual cranial nerves are likewise highly conserved. Notable segmental variation is however shown in the location of the VI and IX–XII motoneurons, suggesting the likelihood of homeotic-like changes in relations between rhombomere and neuronal ‘identity’ during vertebrate evolution. Since experimentally induced shifts in expression borders of Hox genes appear to be correlated with alterations in segment identity and/or neuronal phenotype, the need for further examination of segmental locations of specific neuronal groups and the segmental expression patterns of Hox genes between species is emphasized. Comparison of early cranial mesodermal subdivisions in elasmobranchs with descriptions of somitomeres in amniotes suggests that a series of axially unique mesodermal populations may also be conserved throughout vertebrates. The possibility is raised that common mechanisms of axial specification may underlie the initial appearance of segmental patterning in both neural and mesodermal layers during gastrulation. Implications of these conserved patterns for understanding the phylogenetic origin of the vertebrate head are briefly discussed.

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The histogenesis of the isthmic nuclei in chick embryos (Gallus domesticus)

Cited by 63 publications

References 18 publications

Morphogenesis of the Medaka Cerebellum, with Special Reference to the Mesencephalic Sheet, a Structure Homologous to the Rostrolateral Part of Mammalian Anterior Medullary Velum

Morphogenesis of the Medaka Cerebellum, with Special Reference to the Mesencephalic Sheet, a Structure Homologous to the Rostrolateral Part of Mammalian Anterior Medullary Velum

bHLH transcription factor Her5 links patterning to regional inhibition of neurogenesis at the midbrain-hindbrain boundary

Conservation of Neuroepithelial and Mesodermal Segments in the Embryonic Vertebrate Head

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