caa a22 4500 477095429 CHVBK 20180405111526.0 cr unu---uuuuu 170330e19960401xx s 000 0 eng 10.1007/BF00186691 doi (NATIONALLICENCE)springer-10.1007/BF00186691 Ultrastructural characterization of the postnatal development of the thalamic ventrobasal and reticular nuclei in the rat [Elektronische Daten] [S. De Biasi, A. Amadeo, P. Arcelli, C. Frassoni, A. Meroni, R. Spreafico] Electron microscopy has been employed to analyze the normal maturationai sequence that characterizes the postnatal development of synaptic circuits in the ventrobasal (VB) and reticular (Rt) thalamic nuclei of rats at different ages (from birth to the end of the third postnatal week). Throughout the first postnatal week, similar signs of immaturity are observed in both nuclei, mainly consisting in scarcity of cytoplasmic organelles, presence of wide extracellular spaces, and absence of myelinated fibers. Several synaptic terminals are however present from birth, thus indicating that some of the afferents have already reached and contacted their thalamic target during embryonic life. Most of the terminals are small and contain only a few round, clear vesicles, and therefore their cytological features do not allow the identification of their origin. In particular, in both nuclei, terminals with flat vesicles and symmetric specialization are only rarely observed, and in VB the ascending terminals are not distinguishable from terminals of other sources as they are in adults. During the second postnatal week, progressive maturationai changes in VB and Rt lead to neurons having well-developed cytoplasmic organelles and to an elaborate neuropil containing myelinated fibers and synaptic terminals that are morphologically heterogeneous and resemble the adult ones. The permanence of growth cone-like profiles and of numerous somatic and dendritic protrusions, often contacted by synaptic terminals, indicates that a certain degree of reorganization is still taking place in both nuclei. By the end of the third postnatal week the synaptic organization of VB and Rt is indistinguishable from that observed in adults. This ultrastructural study shows that the appearance of the neuropil of VB and Rt and the morphological complexity of the synaptic arrangements characteristic of the adult rat are not present in neonates, but are gradually acquired during the first three postnatal weeks, and that they result from progressive modifications in circuit organization involving both pre- and postsynaptic elements. Springer-Verlag, 1996 Thalamus nationallicence Somatosensory system nationallicence Synaptogenesis nationallicence Nervous system nationallicence Electron microscopy nationallicence PB : Phosphate buffer nationallicence Rt : reticular nucleus nationallicence SCV : small clear vesicles nationallicence VB : ventrobasal nucleus nationallicence De Biasi S. Sezione di Istologia ed Anatomia Umana, Dipartimento di Fisiologia e Biochimica Generali, Università di Milano, Via Celoria 26, I-20133, Milano, Italy aut Amadeo A. Sezione di Istologia ed Anatomia Umana, Dipartimento di Fisiologia e Biochimica Generali, Università di Milano, Via Celoria 26, I-20133, Milano, Italy aut Arcelli P. Sezione di Istologia ed Anatomia Umana, Dipartimento di Fisiologia e Biochimica Generali, Università di Milano, Via Celoria 26, I-20133, Milano, Italy aut Frassoni C. Dipartimento di Neurofisiologia Sperimentale, Istituto Neurologico "C.Besta”, Milano, Italy aut Meroni A. Sezione di Istologia ed Anatomia Umana, Dipartimento di Fisiologia e Biochimica Generali, Università di Milano, Via Celoria 26, I-20133, Milano, Italy aut Spreafico R. Dipartimento di Neurofisiologia Sperimentale, Istituto Neurologico "C.Besta”, Milano, Italy aut Anatomy and Embryology Springer-Verlag 193/4(1996-04-01), 341-353 0340-2061 193:4<341 1996 193 429 https://doi.org/10.1007/BF00186691 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/BF00186691 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- De Biasi S. Sezione di Istologia ed Anatomia Umana, Dipartimento di Fisiologia e Biochimica Generali, Università di Milano, Via Celoria 26, I-20133, Milano, Italy aut NATIONALLICENCE 700 1- Amadeo A. Sezione di Istologia ed Anatomia Umana, Dipartimento di Fisiologia e Biochimica Generali, Università di Milano, Via Celoria 26, I-20133, Milano, Italy aut NATIONALLICENCE 700 1- Arcelli P. Sezione di Istologia ed Anatomia Umana, Dipartimento di Fisiologia e Biochimica Generali, Università di Milano, Via Celoria 26, I-20133, Milano, Italy aut NATIONALLICENCE 700 1- Frassoni C. Dipartimento di Neurofisiologia Sperimentale, Istituto Neurologico "C.Besta”, Milano, Italy aut NATIONALLICENCE 700 1- Meroni A. Sezione di Istologia ed Anatomia Umana, Dipartimento di Fisiologia e Biochimica Generali, Università di Milano, Via Celoria 26, I-20133, Milano, Italy aut NATIONALLICENCE 700 1- Spreafico R. Dipartimento di Neurofisiologia Sperimentale, Istituto Neurologico "C.Besta”, Milano, Italy aut NATIONALLICENCE 773 0- Anatomy and Embryology Springer-Verlag 193/4(1996-04-01), 341-353 0340-2061 193:4<341 1996 193 429 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer