Electron microscopic observations on the development of the median eminence in perinatal rats

Daikoku, Shigeo; Kotsu, Tadao; Hashimoto, Mitsuko

doi:10.1007/bf00519918

Cited by 45 publications

(5 citation statements)

References 60 publications

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“…Anatomical evidence (GIydon 1957;Campbell 1966) ink perfusion indicated that the development of the capillary tufts of the median eminence begins on the 5th postnatal day with increasing development and complexity continuing until day 40. These studies have been corroborated at the ultrastructural level in the rat (Daikoku et al 1971 ) and mouse (Eurenius and Sarskar 197 1 ) , confirming that capillary invagination of the median eminence to form the primary plexus does not occur until the 4th postnatal day. Therefore, functional integrity of the hypothalarncr-pituitary axis is not expected until the devel~pment of an anatomical communication between the two sites.…”

Section: Discussionsupporting

confidence: 57%

The development of the hypothalamo–pituitary axis in the neonatal rat: sexual maturation in male and female rats as assessed by hypothalamic LHRH and pituitary and serum LH and FSH concentrations

Dussault¹,

Walker²,

Dubois³

et al. 1977

Can. J. Physiol. Pharmacol.

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1977. The development of the hypothalamo-pituitary axis in the neonatal rat: sexual maturation in male and female rats as assessed by hypothalamic LHRH and pituitary and serum L H and FSH concentrations. Can. J. Physiol. Pharmaeol. 55, 109 1-1097.Using specific radioimmltnoassay techniques, we have measured hypothalamic LHRH concentration and pituitary and serum LH and FSH concentrations in neonatal rats from 0 to 60 days after birth. There were no sex differences demonstrable for hypothalamic EHRH concentration, which rose from minimal values at 2 days to peak concentrations at 22-28 days and declined significantly with the approach of puberty. Pituitary LH concentration in the two sexes rose to peak values at 19-25 days, with significantly higher values observed in females ( p < 0.01 ). Serum L H concentration was high in both sexes at birth, the values in females being significantly higher than those observed in males ( p < 0.01 ). While the serum E H concentration remained relatively stable throughout the study period in males, it declined rapidly to a nadir at 28 days in females. Pituitary FSW concentration was low at birth in both sexes. Females demonstrated a marked rise to peak concentrations at 16 days while males achieved significantly lower peak preplilberal values ( p < 0.01) at 28 days. Serum FSH concentration was significantly higher in females ( p < 0.01) at birth and rose further to peak values at 16 days. Males attained peak serum FSH concentrations at 35 days. These data demonstrate that the maturation of the hypothalan~o-pituitary-gonadal axis develops in the neonatal period in the rat and confirm the presence of significant differences in hypothalamic sexual differentiation and control. The possibility of this developmental process in the neonatal rat as a model for the study of the midgestational hypothalamic maturation of the human foetus is discussed. BUSSAUH.T, J. H.. WALKER, P., DUROIS, J. D. et LABRIE, F. 1977. The development of the hypothalamo-pituitary axis in the neonatal rat: sexual maturation in male and female rats as assessed by hypothalamic L H R H and pituitary and serum L H and FSH concentrations. Can. J. Physiol. Pharmacol. 55, 1091-1097.A l'aide de techniques sptcifiques de dosage radioimmunologique, nous avons mesurt la concentration hypothalamique de LHRH, ainsi que les concentrations pituitaires et striques de L H et de FSH chez des rats nouveaux-nCs de 0 B 60 jours aprks la naissance, On ne peut mettre en Cvidence de diffkrences significatives, selon le sexe. pour les concentrations hypothalamiq~ies de L H R H q i~i s'elevent de valeurs minimales i 2 jours jusqu'i des concentrations maximales B 22-28 jours et diminuent de fagon significative i I'approche de la puberth. La concentration de LH pituitaire chez les deux sexes s'eleve B des valeurs maximales 2 19-25 jours avec des valeurs significativement plus Clevkes chez les femelles (p < 0.81). Les concentrations driques de LH demeurent relativement stables chez les mfles au cours de la p6riode d'dtude, mais elles diminue...

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Section: Discussionsupporting

confidence: 57%

The development of the hypothalamo–pituitary axis in the neonatal rat: sexual maturation in male and female rats as assessed by hypothalamic LHRH and pituitary and serum LH and FSH concentrations

Dussault¹,

Walker²,

Dubois³

et al. 1977

Can. J. Physiol. Pharmacol.

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“…In the fetal synaptosomes, SAV were of the same size (mean 420 A) as reported for adults (Whittaker 1972). This is in agreement with a study on the median eminence of the rat where SAV did not appear to change in size during pre-or postnatal development (Kobayashi et al 1968, Daikoku et al 1971.…”

Section: Discussionsupporting

confidence: 89%

“…During the last decade, several investigations have dealt with the fine structure of synaptogenesis in several animal species , In the rat postnatal synaptogenesis has been investigated in many brain areas including the neocortex, the lateral geniculate nucleus, the olfactory bulb, the parietal cortex, the cerebellar cortex, the hippocampus, the superior colliculus, the dentate gyrus, the corpus striatum and the lateral vestibular nucleus (see . Some reports on fetal synaptogenesis have also appeared (Kobayashi et al 1968, Daikoku et al 1971, Del Cerro and Snider 1972, May and Biscoe 1973, Vaughn and Grieshaber 1973, Konig et al 1975. Judging from the currently available literature, it seems reasonable to assume that while mature synapses can be found during prenatal development in the rat, the period of rapid increase in number of synapses in most parts of the brain is during the first three postnatal weeks (e.g., Aghajanian andBloom 1967, Woodward et al 1971).…”

Section: Discussionmentioning

confidence: 99%

Ultrastructure of synaptosomes from fetal rat brain

Kanerva

Hervonen²,

Tissari

1978

Acta Physiologica Scandinavica

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The crude mitochondrial fraction P2 and subfractions of P2 were prepared from the brain stem, hemispheres and whole brain of 19-day-old fetal rats. Samples were fixed in glutaraldehyde-osmium, NaMnO4 or by Tranzer's triple fixation method (aldehydr-chromate-dichromate-osmium) and examined by electron microscopy. The C-fraction from whole brain was the main synaptosome fraction, containing 3.2% presynaptic terminals as counted from all membrane bound particles. The brain stem showed more presynaptic terminals than the hemisphere (2.8% versus 0.9%) suggesting a caudal-rostral maturation gradient for synaptogenesis. The maturity of the nerve endings obtained was very variable in contrast to the rather uniform synaptosomes derived from adult tissue. They varied from profiles without any substructures to mature synaptosomes displaying asymmetric synaptic junctions. Monoamine synaptosomes containing small granular vesicles were not detected in the present study, suggesting immaturity of the granular monoamine pool at this stage of development.

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“…Rapid development of the median eminence (ME) and arcuate nucleus is apparent between the 18th day of gestation and the first 2 weeks of postnatal life (28)(29)(30)(31)(32). Dopamine and norepinephrine appear in the arcuate nucleus at 20 days of gestation but not until after birth in the ME eminence (33, 34), although they are present elsewhere in the brain earlier in development (35).…”

Section: Introductionmentioning

confidence: 99%

The Neuroendocrine Regulation and Function of Growth Hormone and Prolactin in the Mammalian Fetus*

1981

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Electron microscopic observations on the development of the median eminence in perinatal rats

Cited by 45 publications

References 60 publications

The development of the hypothalamo–pituitary axis in the neonatal rat: sexual maturation in male and female rats as assessed by hypothalamic LHRH and pituitary and serum LH and FSH concentrations

The development of the hypothalamo–pituitary axis in the neonatal rat: sexual maturation in male and female rats as assessed by hypothalamic LHRH and pituitary and serum LH and FSH concentrations

Ultrastructure of synaptosomes from fetal rat brain

The Neuroendocrine Regulation and Function of Growth Hormone and Prolactin in the Mammalian Fetus*

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