The major efferent projections of Ad are to: (1) the striatum of avian basal ganglia; (2) a dorsal thalamic zone (including the song-control nuclei dorsomedial nucleus of the posterior thalamus [ DMP] and dorsolateral nucleus of the medial thalamus [ DLM]); (3) restricted regions within the lateral hypothalamus (Stratum cellulare externum [ SCE]), which may also relay information to the same dorsal thalamic zone; (4) a nucleus in the caudal thalamus (medial spiriform nucleus [ SpM]); (5) deep layers of the tectum, which project to the thalamic song-control nucleus Uva; (6) broad regions of pontine and midbrain reticular formation; and (7) areas within the ventral tegmental area and substantia nigra (ventral tegmental area [ AVT], substantia nigra [ SN]), which overlap with regions that project to Area X, a song-control nucleus of avian striatum. 
Extensive but more diffuse terminal fields were also present in the Stratum cellulare externum of the posterior hypothalamus, the central periaqueductal gray, the prerubral field, and the lateral and ventrolateral tegmentum of the pons and medulla.
n., Stratum cellulare externum, inferior hypo.
The distribution of these labeled neurons continued to the more caudal areas such as the vicinity of the nucleus periventricularis hypothalami (PHN), areas medial to the Stratum cellulare externum (SCE), the nucleus interstitialis (IS), and the posterior hypothalamic areas.
Electron microscopy of the Stratum cellulare externum of the optic tectum of an elasmobranch revealed the presence of two types of presynaptic dendrites in the neuropil as well as axo-dendritic synapses.
A small projection from the intercalate division of CbM travels in BC and projects upon the midbrain central grey, the intercollicular nucleus, the lateral tectal periventricular grey, the Stratum cellulare externum and, sparsely, upon the dorsolateral thalamus. The ascending system projects upon the red nucleus and the dorsally adjacent interstitial nucleus of Cajal and midbrain central grey, the prerubral fields continuing into the Stratum cellulare externum, the nucleus intercalatus thalami, the ventrolateral thalamic nucleus, the medial spiriform nucleus, the nucleus principalis precommissuralis, the nucleus of the basal optic root, the nucleus geniculatus lateralis pars ventralis, the dorsolateral thalamus, including the dorsal intermediate posterior, and the dorsolateral intermediate and anterior nuclei.
subrotundus (SRt) and possibly Stratum cellulare externum and internum (SCE/SCI).
These targets include the inferior olive, the cerebellum, the lateral pontine nucleus, the nucleus papillioformis, the nucleus of the basal optic root, the nucleus mesencephalicus profundus, pars ventralis, the nucleus principalis precommissuralis, and the Stratum cellulare externum.
Labeled perikarya were found in the bed nucleus of the stria terminalis (BNST), ventral paleostriatum, and Stratum cellulare externum (SCE) of the lateral hypothalamus, and in the medial hypothalamus, nucleus periventricularis magnocellularis (PVM), which is the avian homologue to a portion of the mammalian paraventricular nucleus.
praeopticus periventricularis and medialis, paraventricularis, supraopticus medialis, lateralis, ectomamillaris and in the Stratum cellulare externum.
Mesencephalic cells of origin of tectal afferent pathways were identified in the Stratum cellulare externum of the contralateral tectum, in the nucleus tegmentalis lateralis, in the ventrolateral tegmentum, and in the nucleus ruber.
In contrast to past data reported for the albino rat, the pigeon, Columba livia and barbary dove, Streptopelia risoria, bilateral destruction of the chick lateral hypothalamic area (LHy), quinto-frontal tract (QF), and Stratum cellulare externum (SCE) resulted in transient aphagia and rapid recovery of lost body weight.
In Scyliorhinus most primary optic fibers terminate in the stratum medullare externum of the mesencephalic tectum, while in Raja the zona externa of the Stratum cellulare externum receives the bulk of the retinal input. In elasmobranch fish the optic nerve fibers enter the tectum through the zona interna of the Stratum cellulare externum and send their axons into the more superficial tectal layers, while in actinopterygians and amphibians the majority of the optic fibers enter the tectum through the superficial layer and distribute their axons to deeper tectal layers..
Bilateral lesions in the Stratum cellulare externum of one animal had a specific effect on the arousal response to a quinine hydrochloride solution and it was concluded that it is possible to indicate deficits following brain lesion in the gustatory system using the EEG..
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