Development of the hypothalamic luteinizing hormone-releasing hormone-containing neuron system in the rat: In vivo and in transplantation studies

Daikoku‐Ishido, Harumi; Okamura, Yoshihiro; Yanaihara, Noboru; Daikoku, Shigeo

doi:10.1016/0012-1606(90)90087-y

Cited by 106 publications

(68 citation statements)

References 33 publications

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“…Recently, it has been asserted that GnRH neurons originate from the olfactory placodes [2][3][4][5][6][7][8][9][10][11][12], This hypothesis is sup ported by observations using immunocytochemical and in situ hybridization studies performed in the normal mouse embryo [2][3][4][5] and further indicated by the observa tion during embryonic development of GnRH neuron migration in the chick [6][7], in the rhesus macaque [8] and in the rat [9]. Moreover, other experimental studies seem also to reinforce this hypothesis: (1) unilateral abla tion of the olfactory placode in the chick at stage 24 of H.H [11]; (2) unilateral ablation of the olfactory placode in newts [12]; (3) tissue transplantation from rat embryo donors aged from 12.5 to 17.5 days of gestation into the adult third ventricle [9], However, it should be noted that these studies have been performed too late, at stages of development when organogenesis has already taken place. In our study, the surgical ablation of different pre sumptive territories was made at stages 7-8 of H.H, dur ing the early somitic stages, before the fusion of the lateral neural folds.…”

Section: Discussionmentioning

confidence: 99%

Experimental Evidence for an Early Commitment of Gonadotropin-Releasing Hormone Neurons, with Special Regard to Their Origin from the Ectoderm of Nasal Cavity Presumptive Territory

El-Amraoui

Dubois²

1993

Neuroendocrinology

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The origin and the migration of gonadotropin-releasing hormone (GnRH)-producing neurons were studied using the indirect immunoperoxidase method in normal and surgically operated chick embryos. In normal embryos, during early embryonic development, GnRH neurons were located only in the respiratory and the olfactory epithelia. Then, these neurons followed the nearest nerve bundle and occupied, thereafter, the dorsal, medial or ventral part of the olfactory nerve according to the time and area of the olfactory epithelium they emerged from. At the junction with the forebrain, the majority of GnRH neurons passed ventromedially round the olfactory bulb. Therefore, they penetrated through the interhemispheric space and coursed obliquely toward caudal and dorsal telencephalon from where they will be later distributed to reach their adult-like position. In view of the large distribution of these neurons in the nasal region, unilateral surgical ablation either of the whole or of each presumptive territory of nasal structures was performed from 2 to 4 somite stages. As expected, when both olfactory placode and ectoderm of nasal cavity presumptive territories were unilaterally removed, olfactory nerve, nasal structures and GnRH neurons failed to develop in the operated side. After the unilateral removal of the olfactory placode anlage, the distribution pattern of GnRH neurons was not disturbed in the operated as well as in the control side although ipsilateral olfactory structures were greatly reduced. In contrast, when the presumptive ectoderm of nasal cavity was unilaterally removed, GnRH neurons were detected only in the control side where this territory was left intact. Therefore, from early neurogenesis, GnRH neurons seem to be already committed, and they originate from the ectoderm of nasal cavity presumptive territory.

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Section: Discussionmentioning

confidence: 99%

Experimental Evidence for an Early Commitment of Gonadotropin-Releasing Hormone Neurons, with Special Regard to Their Origin from the Ectoderm of Nasal Cavity Presumptive Territory

El-Amraoui

Dubois²

1993

Neuroendocrinology

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“…Recent studies in the mouse [19,20], rat [21], and rhesus monkey [22] revealed that GnRH neurons arise from the olfactory placode and migrate into the brain along the ter minal nerve. This occurs during late gestation in the ro dent, and in the first quarter of fetal development in the rhesus monkey.…”

Section: Discussionmentioning

confidence: 99%

GnRH Neurons in the Fetal Lamb Hypothalamus Are Similar in Males and Females

et al. 1992

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The critical period for sexual differentiation of the brain of the developing lamb occurs before birth. Exposure to steroids during this sensitive period in midgestation alters the control of GnRH secretion after birth. The present study examined neurons immunolabeled for GnRH in male and female lambs during the critical period for sexual differentiation to determine if these neurons are sexually dimorphic. Neuron number, anatomical distribution, and the number of neuronal processes of GnRH-containing neurons from midgestation (85 days) male and female fetuses were compared (n = 5 each). Immu-noreactive cells were labelled using LR-1 as the primary antiserum, followed by a biotinylated secondary antibody and the formation of an avidin-biotin-horseradish peroxidase (HRP) complex. The HRP was visualized histochemically using diaminobenzidine as the chromagen. GnRH neurons were localized in 60 µm coronal sections from the area of the diagonal band of Broca to the rostral mammillary bodies. The neurons were classified as unipolar, bipolar, or multipolar, according to the number of neuronal processes. The number of neuronal processes, the pattern of distribution, and the estimated total number of GnRH neurons in male and female fetuses was similar (p > 0.05). Furthermore, these parameters were equivalent to those reported for the adult female. These data indicate the GnRH neurosecretory system matures prior to midgestation in the sheep, and in a similar manner in males and females.

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“…Cells of one type correspond to migrating LHRH neurons (Wray et al, 1989;Daikoku-Ishido et al, 1990;Ronnekleiv and Resko, 1990;Schwanzel-Fukuda and Pfaff, 1990;Norgren and Lehman, 1991). However, several experiments suggest that glial cells also arise in the olfactory epithelium and migrate into the olfactory nerve.…”

Section: Origin and Development Of Olfactory Nerve Gliamentioning

confidence: 99%

Development of olfactory nerve glia defined by a monoclonal antibody specific for schwann cells

Norgren

Ratner

Brackenbury

1992

Developmental Dynamics

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Although there is considerable interest in the possible role of olfactory glia in the pathfinding abilities of olfactory nerve axons, the complete development of these glia in vivo has not been described. Using a specific Schwann cell marker, the 1E8 antibody, we have found that olfactory nerve glia can be identified throughout development. These glia appear to originate in the olfactory placode and migrate initially into the periphery of the olfactory nerve, and later into the center of the nerve. Olfactory nerve glia enter the presumptive olfactory bulb with the olfactory receptor neuron axons and distribute themselves along the edge of the olfactory nerve layer. The fact that olfactory nerve glia are specifically immunostained by the lE8 monoclonal antibody, which recognizes the Schwann cell-specific protein Po, suggests that these cells more closely resemble Schwann cells than astrocytes or enteric glia. These results support and extend previous findings suggesting that olfactory nerve glia have distinctive developmental and anatomical features which may be important to the regenerative capacity of the olfactory system. 0 1992 Wiley-Liss, Inc.

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Development of the hypothalamic luteinizing hormone-releasing hormone-containing neuron system in the rat: In vivo and in transplantation studies

Cited by 106 publications

References 33 publications

Experimental Evidence for an Early Commitment of Gonadotropin-Releasing Hormone Neurons, with Special Regard to Their Origin from the Ectoderm of Nasal Cavity Presumptive Territory

Experimental Evidence for an Early Commitment of Gonadotropin-Releasing Hormone Neurons, with Special Regard to Their Origin from the Ectoderm of Nasal Cavity Presumptive Territory

GnRH Neurons in the Fetal Lamb Hypothalamus Are Similar in Males and Females

Development of olfactory nerve glia defined by a monoclonal antibody specific for schwann cells

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