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Serotonergic innervation of the lateral geniculate nucleus of the rat during postnatal development: A light and electron microscopic immunocytochemical analysis
Author(s) -
Dinopoulos A.,
Dori I.,
Parnavelas J. G.
Publication year - 1995
Publication title -
journal of comparative neurology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.855
H-Index - 209
eISSN - 1096-9861
pISSN - 0021-9967
DOI - 10.1002/cne.903630403
Subject(s) - serotonergic , biology , geniculate , nucleus , anatomy , lateral geniculate nucleus , neuroscience , dorsal raphe nucleus , serotonin , visual cortex , receptor , biochemistry
The serotonergic innervation of the developing lateral geniculate nucleus of the rat was studied with immunocytochemical techniques at the light and electron microscope levels. A relatively small number of thick serotonergic fibers were observed at the time of birth, distributed more densely in the ventral portion of the nucleus and in the intergeniculate leaflet than in the dorsal lateral geniculate nucleus. By the end of the first postnatal week, this distribution pattern was more clearly established, but the number of immunoreactive fibers was increased. Thereafter, and until the adult pattern was estabiished at the end of the third postnatal week, serotonergic fibers increased further in number and changed morphologically (e. g., they became finer and more ramified with closely spaced varicosities), but their pattern of distribution remained unchanged. Electron microscopical analysis of the dorsal lateral geniculate nucleus revealed that the vast majority of serotonin varicosities formed asymmetrical synapses with dendritic shafts; axosomatic synapses were a feature of the nucleus only at the time of birth. The proportion of serotonin varicosities forming synapses increased gradually from birth to reach a peak at the end of the second post week, then declined markedly in the following week before increasing again at a later stage. It may be speculated that synapses formed during the first two weeks of life may be related to the involvement of serotonin in the morphogenesis of the lateral geniculate nucleus, whereas those formed later in development may be involved in the mediation of neurotransm effects. © 1995 Wiley‐Liss, Inc.