Browsing by Subject "Neurosecretion"

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    Fine observation on nerves colonizing the regenerating tail of the lizard Podarcis sicula
    (Murcia : F. Hernández, 1990) Alibardi, Lorenzo; Miolo, Valentino
    During the regeneration of lizard tail, nerves sprouting from ganglia and the spinal cord invade the blastema as far as the apical epidermis. Electron microscopical observations reveal axons storing dense granules (dg) and dense core vesicles (dcv) which are concentrated in nerve terminals or in axoplasmatic regions. In the regenerating spinal cord (SC) these terminals resemble aminergic-peptidergic endings and grow as far as the distal portion of the SC, which is made up of irregularly arranged ependymal cells. Some axons storing dcv contact blastematic cells and other nerve terminals show a plasma membrane incomplete or broken. Whether this latter aspect is due to fixation artifacts or physiological rupture is unknown. Nerves containing dcv and a few dg also originate from spinal ganglia innervating the regenerating tail. The accumulation of material into these endings is probably slow and a possible trophic influence on the regeneration of lizard tail is discussed.
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    The distribution of vasotocin and mesotocinimmunoreactivity in the hypothalamic magnocellularneurosecretory nuclei of the Saharan herbivorous lizard,Uromastix acanthinurus Bell, 1825 (Sauria-Agamidae)
    (Murcia : F. Hernández, 2010) Barka-Dahane, Zohra; Bendjelloul, Mounira; Estabel, Jeanne; Exbrayat, Jean-Marie
    An immunohistochemical study of themagnocellular neurosecretory nuclei was performed inthe hypothalamus of the desert lizard Uromastixacanthinurususing polyclonal antibodies againstarginine vasotocin (AVT), mesotocin (MST) andneurophysins I and II (NpI, NpII). AVT- and MST-immunoreactivities were localized in individual neuronsof the supraoptic, periventricular, and paraventricularnuclei and in scattered neurosecretory cells. Thesupraoptic nuclei (SONs) can be subdivided into rostral,medial and caudal portions. The rostral portion of theSONs was called the SON-ventral aggregation (V SON)because the neurosecretory neurons are present in theventral part of the hypothalamus along the optic chiasma(OC). Their perikarya and fibres were only AVT-ir. Themedial part of the SONs was constituted of two clustersof neurosecretory neurons located in the two lateral endsof the OC to form the SON-lateral aggregations (LSON). In the caudal end of the last one, some MST-irperikarya appeared. The caudal part of the SONs wasconstituted of a dorso-lateral aggregation (D SON) of ir-neurons spreading over the lateral forebrain bundle(LFB). AVT- and MST- perikarya were observed in thiscaudal portion of the SONs, AVT-ir neurons being morenumerous. AVTergic and MSTergic magnocellularneurons were present in the periventricular nuclei(PeVNs). Parvocellular and magnocellular AVT- andMST-ir were observed in the paraventricular nuclei(PVNs). The fibres emerging from the magnocellularneurons which belong to these nuclei and the scatteredcells ran along the hypothalamic floor and entered themedian eminence (ME) to end in the neural lobe ofhypophysis. As a rule, immunoreactivity was alsoobserved in all the regions of the forebrain withvasotocinergic and mesotocinergic perikarya and fibres.The immunoreactive distribution was similar to thatdescribed in other reptiles.