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  • 1995-1999  (1)
  • 1990-1994  (3)
  • 1
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neuroendocrinology 6 (1994), S. 0 
    ISSN: 1365-2826
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Localization of GnRH-immunoreactive neuronal system was studied by immunohistochemistry in the nasal-brain area of the crested newt, Triturus carnifex. Besides adults, developmental stages were those from hatchlings up to complete metamorphosis. Neurons containing immunoreactive GnRH were first detected in the nasal area of larvae with yet undifferentiated gonads. Subsequently, in prometamorphic stages, GnRH-immunoreactive cell bodies and fibers were detected in the proximal part of the terminal nerve as well as along the ventromedial surface of the olfactory bulbs. In older larvae with sexually differentiated gonads and up to the metamorphic climax GnRH-neurons were detected, as a rostral to caudal continuum, along the ventromedial surface of the olfactory bulbs and midtelencephalon. This is exactly the route followed by the terminal nerve. In the adult brain, besides the presence of occasional GnRH-neurons and fibers in the terminal nerve proximal to olfactory bulbs, olfactory bulbs and the mid-basal telencephalon, another aggregate of immunoreactive neurons was present in the anterior preoptic area, and a greater number of fibers in the habenular area as well as in the infundibular floor, median eminence and pars nervosa. These data suggest the nasal area to forebrain migration (along the course of the terminal nerve) of GnRH-neurons during development in the crested newt.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Science Ltd
    Journal of neuroendocrinology 9 (1997), S. 0 
    ISSN: 1365-2826
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Mammalian and chicken-II forms of gonadotropin-releasing hormone (mGnRH and cGnRH-II, respectively) have been measured simultaneously in the brain, pituitary, and peripheral terminal nerves (nasal area tissue) of adult males and females of a representative amphibian, Rana esculenta, during the annual reproductive cycle. Whereas in the male, brain concentrations of both GnRH forms showed significant reproductive status-related fluctuations, in the female brain only cGnRH-II content showed significant changes. The highest GnRH levels were recorded just prior to breeding in both sexes. In the pituitary both GnRHs were present in all seasons. In the peripheral terminal nerves, instead, only mGnRH was detected in all seasons confirming our previous immunohistochemical data. In both sexes furthermore, the brain and pituitary mGnRH levels were consistently much higher than those of cGnRH-II and there were no sex-related differences in the brain and pituitary content of GnRHs. Seasonal changes in brain GnRH levels may correlate with plasma sex steroid levels reinforcing the postulate that sex steroids affect GnRH neuronal systems.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neuroendocrinology 3 (1991), S. 0 
    ISSN: 1365-2826
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Immunohistochemical mapping with antibodies against four different types of gonadotropin-releasing hormone (GnRH)-like neuro-peptides has been studied in the brain of adult Rana esculenta. This study confirms the earlier described distribution pattern of the immunoreactive mammaiian GnRH system in the frog brain, as well as revealing that this system of neuronal cell bodies and fibres is immunopositive to antisera for mammalian, chicken-I, chicken-II and salmon GnRH-like molecules. The results also indicate coexistence of the four GnRH variants in the same anatomical areas. The presence of immunoreactive fibre endings in the cerebellum is also described, perhaps for the first time in the vertebrate brain. In addition, it was found that many immunoreactive GnRH fibres arising in the anterior preoptic area and thalamus-periventricular area project posteriorly to reach the interpeduncular nucleus-tegmentum area, thus connecting the diencephalon with the rhombencephalon. These data provide further information on the complex GnRH system in the frog brain. What role(s) in vivo the non-mammalian forms of GnRH-like peptides may play in amphibian reproduction is briefly discussed, and in the light of paucity of data it is here stressed that more amphibian species should be studied.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1432-0878
    Keywords: Brain ; Gonadotropin-releasing hormone ; Spermatogenesis ; Reproductive cycle ; Immunohistochemistry ; Development, ontogenetic ; Rana esculenta (Anura)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The distribution and density of cell bodies and fibers immunoreactive to GnRH-like peptides were investigated in the brain of male juvenile frogs (Rana esculenta) during postmetamorphic development. An immunohistochemical technique was used, involving antisera raised against 4 variants of GnRH: mammalian GnRH, chicken GnRH-I, chicken GnRH-II and salmon GnRH. A comparison of the immunohistochemical distribution at 8 different developmental stages shows that the maximum density of immunoreactive-GnRH elements, and the full distributional complexity of this system, is attained at the completion of spermatogenesis. Immunoreactive-GnRH cell bodies first appear in the anterior preoptic area during the metamorphic climax, and then appear sequentially in the medial septal area, tegmentum and, lastly, in the retrochiasmatic area and olfactory bulb when immunoreactive-fibers also reach the cerebellum. The GnRH system reacts positively to antisera for all 4 GnRH variants, but immunoreactivity for chicken GnRH-I is the weakest.
    Type of Medium: Electronic Resource
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