Comparative distribution of NADPH-diaphorase activity and tyrosine hydroxylase immunoreactivity in the diencephalon and mesencephalon of the domestic chicken (Gallus domesticus).

We described the distribution of NADPH-diaphorase-containing neurons in relation to tyrosine hydroxylase immunoreactivity in the diencephalon and mesencephalon of the chicken. In the diencephalon, both markers were found in the lateral hypothalamus, dorsal hypothalamic area, hypothalamic periventricular nucleus, paraventricular nucleus and mamillary area. A close examination showed that the fine distribution of these markers differed slightly, so that they were never observed in the same neurons. In the mesencephalon, NADPH-diaphorase and tyrosine hydroxylase immunoreactivity were found in the ventral pedunculopontine area (nucleus tegmenti pedunculopontinus pars compacta, adjacent areas surrounding the quintofrontal tract and the nucleus mesencephalicus profundus ventralis), the coeruleus complex (locus coeruleus, ventral and dorsal subcoeruleus nuclei), the ventral tegmental area and the central gray. The majority of these neurons contained either diaphorase or tyrosine hydroxylase. Nevertheless, in a few cases both markers appeared to colocalize in the same neuron, typically in large perikarya of the ventral pedunculopontine area.

The dorsomedial and dorsolateral forebrain of the zebra finch, Taeniopygia guttata: a Golgi study.

Neurones in the zebra finch dorsal forebrain (hippocampal and lateral corticoid complexes) were described and located using Golgi methods. We distinguish two main classes of neurones, spinous with distant projecting axons, and aspinous with local axons. Spinous neurones are subclassified into bitufted pyramids, localised in the medial hippocampus, modified bitufted pyramids in the intermediate corticoid area, multipolar neurones in the parahippocampal area, lateral hippocampus and corticoid complex, and stellate neurones in the corticoid complex. Among the aspinous neurones, we distinguish neurones with basket axons, dense pericellular axons, radial axons, and net-like axons, and horizontal cells seen in the dorsolateral corticoid area. This group includes sparsely spinous neurones found in the intermediate corticoid area. On the basis of the neuronal characteristics, we divide the hippocampal complex into 5 fields: medial and lateral hippocampus, parahippocampal area, central field of the parahippocampal area, and crescent field. The lateral corticoid complex is subdivided into an intermediate corticoid area and a dorsolateral corticoid area. We conclude that the avian dorsal forebrain is an assembly of fields interconnected by axonal collaterals. The medial hippocampus and possibly the intermediate corticoid area display a primitive cortex-like organisation, whereas the other fields lack any sign of cortical structure.

Histochemical distribution of zinc in the brain of the zebra finch (Taenopygia guttata).

The distribution of zinc was studied in the brain of the zebra finch (Taenopygia guttata) by means of the selenium histochemical method. A specific pattern was seen, which usually correlated with the main known architectonic subdivisions. In addition, a few as yet unidentified structures were observed. In the telencephalon, the pallial components were stained with moderate to strong intensity. The only exceptions were the hyperstriatum intercalatus superior, a small medial area in the hyperstriatum accessorium and in the dorsolateral cortex, and the dorsomedial part of the hippocampal complex, which were virtually devoid of staining. Staining of the dorsal ventricular ridge components varied considerably. The archistriatum, the nucleus accumbens, the nucleus of the stria terminalis, the hyperstriatum ventrale and the lateral septum showed moderate to strong staining. The medial septum was weakly stained. The neostriatum showed a rather complex pattern of staining with unstained areas, such as the magnocellular nucleus of the anterior neostriatum, and other parts intensely stained, especially in its caudal region. Both paleostriatii primitivum and augmentatum showed a rostro-caudal gradient that was increasingly stained. We also observed an intensely stained area ventral to the fasciculus prosencephali lateralis and lateral to the tractus septomesencephalicus, a weakly to moderately stained band ventral to the lobus parolfactorius, an intensely stained zone along the lateral ventricle in the hyperstriatum ventrale, and an unstained almond-shaped nucleus in the lateral hyperstriatum ventrale. In the diencephalon, the hypothalamus showed a moderate to strong, rather uniform staining, whereas the thalamus was usually weakly to moderately stained, with the exception of a few unstained nuclei. Only the lateral nucleus of the habenula was stained, and with strong intensity. Most of the mesencephalon stained rather uniformly with a moderate to strong intensity. The most intense staining was seen in the substantia grisea centralis, the substantia grisea et fibrosa periventricularis, the torus semicircularis and the nucleus intercollicularis. The tectum opticum was virtually devoid of stain except for two light bands in the stratum griseum et fibrosum superficiale. The formatio reticularis was moderately stained. All the other structures were either weakly stained or unstained. Some staining was seen in the Purkinje and the granular layers of the cerebellum, as well as around its internal nuclei. The pons and the medulla oblongata showed an overall moderate to intense staining, with the exception of a few unstained nuclei. When compared in three bird species belonging to different genera, zinc distribution shows remarkable similarities, despite species, age and methodological differences.(ABSTRACT TRUNCATED AT 400 WORDS)

A subpopulation of large calbindin-like immunopositive neurones is present in the hippocampal formation in food-storing but not in non-storing species of bird.

The avian hippocampal formation (HP) is thought to play a role in the processing of spatial memory related to food-storing behaviour. The HP of two food-storing species (marsh tit (Parus palustris) and magpie (Pica pica)) and two non-storing species (great tit (Parus major) and jackdaw (Corvus monedula)) were compared following calbindin-like immunostaining. In the dorsal hippocampal region, both species of food-storing birds had larger calbindin-immunoreactive cells than did the two non-storing species. The fact that this association between storing behaviour and cell morphology is seen in two unrelated families of birds, the Paridae (marsh tit versus great tit) and Corvidae (magpie versus jackdaw) suggests that there may be a direct link between food-storing behaviour and the dorsal hippocampal calbindin-immunoreactive cell population.

Structural plasticity in the rat supraoptic nucleus during gestation, post-partum lactation and suckling-induced pseudogestation and lactation.

In the supraoptic nucleus (SON) of parturient and lactating rats, large portions of the surface membranes of almost all oxytocinergic neurons are directly juxtaposed with no glial interposition. A significant number of the same neurones are also contacted by the same presynaptic terminal ('double' synapses). Our present observations have revealed that direct appositions between adjacent neurons in the SON increase quite rapidly during the day before parturition. 'Double' synapses also become visible during late gestation, but they appear more progressively. Earlier studies have shown that 1 month after weaning, as in virgin rats, there are again very few appositions and 'double' synapses in the nucleus. We show here that the SON can remain structurally modified, and to the same degree, beyond normal weaning time so long as lactation is prolonged by renewing suckling litters. However, if the mothers are deprived of their pups immediately after birth, neuronal appositions disappear within 2 days and 'double' synapses by 10 days. In non-pregnant primiparous rats, continuous exposure to suckling litters leads to pseudogestation and eventually lactation (in 16-22 days). Examination of the SON in such animals revealed that the oxytocinergic system is already modified by day 12 of dioestrus; during suckling-induced lactation, the anatomical changes are identical to those seen during a normal post-partum lactation. These observations indicate that neither gestation nor suckling alone are indispensable for the anatomical reorganization of the SON apparent at lactation.(ABSTRACT TRUNCATED AT 250 WORDS)