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1. |
Evolution of Nerve Development in Frogs; pp. 61–73 |
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Brain, Behavior and Evolution,
Volume 50,
Issue 2,
1997,
Page 61-73
Gerhard Schlosser,
Gerhard Roth,
Preview
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PDF (2842KB)
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摘要:
The gross anatomical development of the peripheral nervous system (PNS) during embryogenesis and metamorphosis in the frog Discoglossus pictus is described based on whole-mount immunostaining for nerves and muscles. In the head, neurite outgrowth starts with the mandibular ramus of the trigeminal nerve at the tailbud stage. Cranial muscles are innervated as soon as they differentiate, beginning at mid-embryonic stages. During late embryonic stages, the course of the trigeminal and facial nerves becomes greatly distorted and changes again drastically during metamorphosis accompanying the reorganization of the jaw muscles. Two occipital somites and nerves develop transitorily but degenerate at late embryonic stages. The hypoglossal nerve develops by fusion of the first and second spinal nerves and receives a transitory contribution of the third and fourth spinal nerve at embryonic stages. In the trunk, several classes of Rohon-Beard neurites could be identified at embryonic stages, one of which forms intersegmental sensory nerves that prefigure the course of the sensory rami of spinal nerves at later stages. We give detailed schedules of PNS and cranial muscle de-velopment which, in comparison with data on other frog species described in a companion paper, will serve as a basis to evaluate heterochronic shifts during evolution of PNS development in frogs.
ISSN:0006-8977
DOI:10.1159/000113323
出版商:S. Karger AG
年代:1997
数据来源: Karger
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2. |
Evolution of Nerve Development in Frogs; pp. 74–83 |
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Brain, Behavior and Evolution,
Volume 50,
Issue 2,
1997,
Page 74-83
Gerhard Schlosser,
Gerhard Roth,
Preview
|
PDF (1673KB)
|
|
摘要:
The gross anatomical development of the peripheral nervous system (PNS) during embryogenesis and metamorphosis in the frog Discoglossus pictus is described based on whole-mount immunostaining for nerves and muscles. In the head, neurite outgrowth starts with the mandibular ramus of the trigeminal nerve at the tailbud stage. Cranial muscles are innervated as soon as they differentiate, beginning at mid-embryonic stages. During late embryonic stages, the course of the trigeminal and facial nerves becomes greatly distorted and changes again drastically during metamorphosis accompanying the reorganization of the jaw muscles. Two occipital somites and nerves develop transitorily but degenerate at late embryonic stages. The hypoglossal nerve develops by fusion of the first and second spinal nerves and receives a transitory contribution of the third and fourth spinal nerve at embryonic stages. In the trunk, several classes of Rohon-Beard neurites could be identified at embryonic stages, one of which forms intersegmental sensory nerves that prefigure the course of the sensory rami of spinal nerves at later stages. We give detailed schedules of PNS and cranial muscle de-velopment which, in comparison with data on other frog species described in a companion paper, will serve as a basis to evaluate heterochronic shifts during evolution of PNS development in frogs.
ISSN:0006-8977
DOI:10.1159/000113324
出版商:S. Karger AG
年代:1997
数据来源: Karger
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3. |
Evolution of Nerve Development in Frogs; pp. 84–93 |
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Brain, Behavior and Evolution,
Volume 50,
Issue 2,
1997,
Page 84-93
Gerhard Schlosser,
Gerhard Roth,
Preview
|
PDF (2190KB)
|
|
摘要:
The gross anatomical development of the peripheral nervous system (PNS) during embryogenesis and metamorphosis in the frog Discoglossus pictus is described based on whole-mount immunostaining for nerves and muscles. In the head, neurite outgrowth starts with the mandibular ramus of the trigeminal nerve at the tailbud stage. Cranial muscles are innervated as soon as they differentiate, beginning at mid-embryonic stages. During late embryonic stages, the course of the trigeminal and facial nerves becomes greatly distorted and changes again drastically during metamorphosis accompanying the reorganization of the jaw muscles. Two occipital somites and nerves develop transitorily but degenerate at late embryonic stages. The hypoglossal nerve develops by fusion of the first and second spinal nerves and receives a transitory contribution of the third and fourth spinal nerve at embryonic stages. In the trunk, several classes of Rohon-Beard neurites could be identified at embryonic stages, one of which forms intersegmental sensory nerves that prefigure the course of the sensory rami of spinal nerves at later stages. We give detailed schedules of PNS and cranial muscle de-velopment which, in comparison with data on other frog species described in a companion paper, will serve as a basis to evaluate heterochronic shifts during evolution of PNS development in frogs.
ISSN:0006-8977
DOI:10.1159/000316296
出版商:S. Karger AG
年代:1997
数据来源: Karger
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4. |
Evolution of Nerve Development in Frogs; pp. 94–112 |
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Brain, Behavior and Evolution,
Volume 50,
Issue 2,
1997,
Page 94-112
Gerhard Schlosser,
Gerhard Roth,
Preview
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PDF (3014KB)
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摘要:
We use whole-mount immunohistochemistry to describe the pattern of development of cranial nerves and muscles in the direct-developing leptodactylid frog Eleutherodactylus coqui. Comparison with nerve development in the biphasically developing frogs Physalaemus pustulosus (Leptodactylidae) and Discoglossus pictus (Discoglossidae; described in a companion paper) allows us to infer the ancestral leptodactylid ontogenetic pattern and the extent to which it has been modified during the evolution of direct development in Eleutherodactylus. While early embryonic development of cranial nerves and muscles is remarkably conserved in E. coqui, most transitory embryonic and larval characters (e.g., occipital and spinal myotomes together with their innervation, the distorted course of trigeminal and facial nerves, ventral branchial arch muscles, a subset of branchial-nerve rami and the lateral-line system never develop. However, a few larva-typical characters are recapitulated, including Rohon-Beard cells and an anastomosis between the vagal and hypoglossal nerve. In addition to the abbreviation of ontogeny by loss of larva-specific traits, dramatic dissociations and heterochronic shifts of character can be observed in E. coqui. The onset of development of limb and trunk innervation has been pre-displaced to early embryonic stages. Moreover, the reorientation of cranial muscles and nerves corresponding to late metamorphic events in biphasically developing anurans occurs relatively much earlier and is less pronounced in E. coqui resulting in an extreme condensation of ontogeny.
ISSN:0006-8977
DOI:10.1159/000113325
出版商:S. Karger AG
年代:1997
数据来源: Karger
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5. |
Evolution of Nerve Development in Frogs; pp. 112–128 |
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Brain, Behavior and Evolution,
Volume 50,
Issue 2,
1997,
Page 112-128
Gerhard Schlosser,
Gerhard Roth,
Preview
|
PDF (3286KB)
|
|
摘要:
We use whole-mount immunohistochemistry to describe the pattern of development of cranial nerves and muscles in the direct-developing leptodactylid frog Eleutherodactylus coqui. Comparison with nerve development in the biphasically developing frogs Physalaemus pustulosus (Leptodactylidae) and Discoglossus pictus (Discoglossidae; described in a companion paper) allows us to infer the ancestral leptodactylid ontogenetic pattern and the extent to which it has been modified during the evolution of direct development in Eleutherodactylus. While early embryonic development of cranial nerves and muscles is remarkably conserved in E. coqui, most transitory embryonic and larval characters (e.g., occipital and spinal myotomes together with their innervation, the distorted course of trigeminal and facial nerves, ventral branchial arch muscles, a subset of branchial-nerve rami and the lateral-line system never develop. However, a few larva-typical characters are recapitulated, including Rohon-Beard cells and an anastomosis between the vagal and hypoglossal nerve. In addition to the abbreviation of ontogeny by loss of larva-specific traits, dramatic dissociations and heterochronic shifts of character can be observed in E. coqui. The onset of development of limb and trunk innervation has been pre-displaced to early embryonic stages. Moreover, the reorientation of cranial muscles and nerves corresponding to late metamorphic events in biphasically developing anurans occurs relatively much earlier and is less pronounced in E. coqui resulting in an extreme condensation of ontogeny.
ISSN:0006-8977
DOI:10.1159/000113326
出版商:S. Karger AG
年代:1997
数据来源: Karger
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