The Ontogeny of Gonadotropin-Releasing Hormone Neurons in the Chick

Sullivan, Kelli A.; Silverman, Ann‐Judith

doi:10.1159/000126598

Cited by 49 publications

(31 citation statements)

References 28 publications

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“…In both organisms, detailed immunocytochemical analysis revealed GnRH+ 4173 RESEARCH ARTICLE Acquisition of olfactory fate cells in the olfactory epithelium, later along the olfactory nerve and finally in the forebrain (Murakami et al, 1991;Norgren and Lehman, 1991;Sullivan and Silverman, 1993;Wray et al, 1989a;Wray et al, 1989b). Furthermore, birth-dating forebrain GnRH neurons suggests they leave the mitotic cycle shortly before GnRH expression is seen in the olfactory epithelium (Mulrenin et al, 1999;Schwanzel-Fukuda and Pfaff, 1989;Wray et al, 1989a).…”

Section: Origin Of Gnrh Neuroendocrine Cellsmentioning

confidence: 99%

Competence, specification and commitment to an olfactory placode fate

Bhattacharyya

Bronner‐Fraser

2008

Development

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Cranial sensory placodes arise as transient thickenings of embryonic head ectoderm (van Wijhe, 1883;von Kupffer, 1891) and invaginate/ingress to form components of the nose, lens and inner ear (Bailey and Streit, 2006; Baker and Bronner-Fraser, 2001;Schlosser, 2006). Of the three sensory placodes, the lens and otic are relatively easy to distinguish and manipulate early in development. Therefore, tissue interactions and signals guiding their induction have been studied extensively (reviewed by Brown et al., 2003;Chow and Lang, 2001;Donner et al., 2006;Grainger, 1992;Noramly and Grainger, 2002;Riley and Phillips, 2003;Saha et al., 1989;Streit, 2001;Torres and Giraldez, 1998).By contrast, development of the olfactory sensory system has been primarily investigated at later stages. An attractive model for studying neurogenesis, its myriad of derivatives include the regenerative odorant sensing olfactory neurons in the olfactory epithelium (Calof et al., 1998;Graziadei and Graziadei, 1979;Graziadei and Metcalf, 1971;Graziadei and Monti Graziadei, 1983), the ingressing gonadotropin-releasing hormone neurons (reviewed by Parhar, 2002;Wray, 2002) [for a contrary view see Whitlock (Whitlock, 2005)], the pheromone-detecting vomeronasal organ (Dulac, 1997) and other neuromodulatory and neuroendocrine cells (Northcutt and Muske, 1994;Tarozzo et al., 1995;Yamamoto et al., 1996). It is the only placode to give rise to glial cells that ingress and migrate along the olfactory nerve towards the brain (Chuah and West, 2002;Ramon-Cueto and Avila, 1998). Cues that guide differentiation along these different pathways and the molecular mechanisms underlying the patterned wiring of olfactory sensory neurons have been examined extensively (reviewed by Baker and Margolis, 2002; Balmer and LaMantia, 2005).Contrasting with this wealth of data, inductive events that initiate olfactory development remain ambiguous, partially because the placode is morphologically invisible until relatively late (HH13+ in birds). Transplantation studies show that precursors straddle the lateral anterior neural folds and adjacent ectoderm in the neurula (Couly and Le Douarin, 1985), but their exact location at intervening stages was unclear. Recent cell marking studies in zebrafish and chick have examined the origin of the olfactory placode at higher resolution and at intervening stages (Bhattacharyya et al., 2004;Whitlock and Westerfield, 2000). Olfactory precursors are initially distributed in a broad region spanning the anterior neural folds and overlapping with lens precursors. Over time, they become progressively restricted to the most anterior ectoderm, finally resolving to a discrete olfactory pit. Knowledge of the location of precursors at different stages has facilitated manipulation of their development.To understand how and when the nasal epithelium is first induced, we examined competence, specification and commitment of ectoderm toward an olfactory fate. This information is a necessary prerequisite for interpreting results of functional perturba...

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Section: Origin Of Gnrh Neuroendocrine Cellsmentioning

confidence: 99%

Competence, specification and commitment to an olfactory placode fate

Bhattacharyya

Bronner‐Fraser

2008

Development

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“…In this species, GnRH-immunoreactive (GnRH-IR) neurons were first detected in the medial part of the olfactory placode at G11; they then migrated along the vomeronasal and the terminal nerves within the nasal septum, entered the forebrain and reached their final location: the septo-preoptic area and the mediobasal hypothalamus [1, 2]. A comparable developmental pattern has been reported in various vertebrates such as chicken [3, 4], the newt [5, 6]and the rhesus monkey [7, 8]. In some species such as the rat [9]and the sheep [10], GnRH-IR neurons could not be detected in the olfactory placode during early embryogenesis.…”

Section: Introductionmentioning

confidence: 80%

Prolonged Neurogenesis during Early Development of Gonadotropin-Releasing Hormone Neurones in Sheep <i>(Ovis aries):</i> In vivo and in vitro Studies

et al. 2003

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Gonadotropin-releasing hormone (GnRH) neurons involved in controlling the reproductive function in vertebrates are derived from the olfactory placode. However, in the sheep and the rat species, GnRH-immunoreactive (GnRH-IR) neurons could not be detected in the olfactory region during the earliest phase of GnRH system development. Using in situ hybridization (ISH) and immunohistochemistry (IHC) in sheep embryos ranging from 26 to 53 days’ gestational age (G26–G53), the present work confirmed that GnRH expression could not be detected during the earliest steps of migration. The first ISH+ cells were detected in the nasal septum and at the entrance of the telencephalon at G33 stage. [³H]-thymidine pulses applied to in vitro olfactory explant cultures showed that GnRH neuron precursor cells have an extended multiplication period corresponding to G26–G36 before entering the neuronal differentiation process. Therefore, the lack of GnRH neuron detection during the early phase of development in the sheep compared to the mouse and other vertebrates represents a major difference in the early development of GnRH neurons. In the mouse, GnRH neuron precursors have a limited multiplication period in the vomeronasal pit and only postmitotic neurons start migration, whereas in the sheep embryo, the multiplication period is extended to about 10 days as demonstrated in olfactory explant cultures.

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“…Similarly, in the chick embryo, several reports have described the migration pathway of LHRH neurons through the nasal septum along the olfactory nerve to the forebrain (Murakami et al, 1991;Norgren and Lehman, 1991;Sullivan and Silverman, 1993). Consistent with this mechanism, either physical interruption of the central projection of olfactory nerve or placodectomy induces a failure of LHRH neurons to migrate from the nasal region to the brain (Akutsu et al, 1992;Murakami et al, 1995Murakami et al, , 1998.…”

mentioning

confidence: 77%

“…After LHRH neurons enter the forebrain, most of them course along the medial forebrain surface toward the septal area (Murakami et al, 1991;Norgren and Lehman, 1991;Sullivan and Silverman, 1993). It has been reported that a subset of olfactory fibers extending into the caudal forebrain develops in association with LHRH neuronal migration.…”

mentioning

confidence: 99%