The aim of the present work was to identify gender-related differences in the dendroarchitectonics of neurons in the posterior cortical nucleus of the amygdaloid body and the role of androgens in forming the dendroarchitectonics during the period of sexual differentiation of the rat brain. 
Sex differences in neuron dendroarchitectonics of the amygdala posterior cortical nucleus of adult rats were described for the first time using the Golgi method.
Significant differences were detected in the label incorporation intensity in the neurons of piriform cortex as compared to that one in neurons of the medial portion of posterior cortical nucleus..
The heaviest projections from the amygdala to the piriform cortex originated in the medial division of the lateral nucleus, the periamygdaloid and sulcal subfields of the periamygdaloid cortex, and the posterior cortical nucleus.
The aim of this study was to establish gender-associated differences in dendroarchitectonics of neurons in posterior cortical nucleus of amygdala and the role of androgens in their formation during the period of sexual differentiation of rat brain.
Another large cluster of retrogradely labeled cells in the lateral division of the amygdalo-hippocampal area, the posterior cortical nucleus (part of the vomeronasal amygdala), and the periamygdaloid cortex (part of the olfactory amygdala), however, had disappeared in epileptic brain in parallel to severe neuronal loss in these nuclei.
The posterior cortical nucleus of the amygdala is involved in the processing of pheromonal information and presumably participates in ingestive, defensive, and reproductive behaviors as a part of the vomeronasal amygdala. Recent studies suggest that the posterior cortical nucleus might also modulate memory processing via its connections to the medial temporal lobe memory system. To investigate the projections from the posterior cortical nucleus to the hippocampal formation and the parahippocampal region, as well as the intra-amygdaloid connectivity in detail, we injected the anterograde tracer phaseolus vulgaris-leucoagglutinin into different rostrocaudal levels of the posterior cortical nucleus. The heaviest intranuclear projection was directed to the deep part of layer I and to layer II of the posterior cortical nucleus. Our data suggest that via these topographically organized projections, pheromonal information processed within the posterior cortical nucleus can influence memory formation in the hippocampal and parahippocampal areas.
In the amygdala, OX1R mRNA was expressed throughout the amygdaloid complex with robust labeling in the medial nucleus, while OX2R mRNA was only present in the posterior cortical nucleus of amygdala.
These areas include the medial division of the lateral nucleus, the parvicellular division of the basal nucleus, the accessory basal nucleus, the posterior cortical nucleus, and portions of the anterior cortical and medial nuclei.
In the kainate model, where the seizure activity was more severe, the accessory basal nucleus, amygdalohippocampal area, posterior cortical nucleus and periamygdaloid cortex were also damaged.
The major intra-amygdaloid projections from the accessory basal nucleus were directed to the medial and capsular divisions of the central nucleus, the medial division of the amygdalohippocampal area, the medial division of the lateral nucleus, the central division of the medial nucleus, and the posterior cortical nucleus.
The major extranuclear projections of the lateral nucleus are (in descending order of magnitude) to the accessory basal nucleus, the basal nucleus, the periamygdaloid cortex, the dorsal portion of the central division of the medial nucleus, the posterior cortical nucleus, the capsular division of the central nucleus, and the lateral division of the amygdalohippocampal area.
Using a monoclonal antibody to GABA, immunoreactive neurons were observed throughout the amygdaloid complex (constituting approximately 20% of the neurons in the lateral nucleus), with higher densities located in the intercalated nuclei, amygdalohippocampal area, and posterior cortical nucleus.
The second large pathway ascends through the medial zone of the hypothalamus and densely innervates the ventrolateral part of the ventromedial nucleus and adjacent basal parts of the lateral hypothalamic area, medial preoptic nucleus, principal nucleus of the bed nuclei of the stria terminalis, ventral lateral septal nucleus, posterodorsal part of the medial nucleus of the amygdala, posterior nucleus, and immediately adjacent regions of the posterior cortical nucleus of the amygdala.
Experiments with fluorogold and phaseolus vulgaris leucoagglutinin (PHAL) indicate that the major neuronal input to the PA arises in the ventral premammillary nucleus, and that substantial projections also arise in olfactory-related areas such as the medial nucleus of the amygdala, bed nucleus of the accessory olfactory tract, and posterior cortical nucleus of the amygdala, as well as in the ventral subiculum and adjacent parts of hippocampal field CA1. The efferent projections of the PA as determined with the PHAL method appear to follow five major routes: 1) a relatively small group of laterally directed fibers innervates the dorsal endopiriform nucleus, and a few of these fibers reach cortical area TR and the lateral entorhinal area; 2) another small group of fibers courses medially to innervate the ventral subiculum and adjacent parts of field CA1; 3) many fibers course ventrally to innervate the outer molecular layer of the medial part of the posterior cortical nucleus of the amygdala; 4) a moderate group of fibers courses rostrally to innervate primarily the posterodorsal part of the medial nucleus of the amygdala, although some fibers continue on to end less densely in rostral parts of the medial nucleus of the amygdala before leaving the amygdala through the ansa peduncularis; and 5) the major output of the PA courses through the stria terminalis.
No fibers projected from the posterior cortical nucleus of the amygdala to the hypothalamus. Most amygdaloid projections to the lateral hypothalamic area originated in the anterior half of the amygdala, while projections to the ventromedial hypothalamic nucleus arose along the entire length of the amygdala except the posterior cortical nucleus.
Following lesion of the posterior cortical nucleus of the amygdala (PCAN), the number of degenerating axon terminals and alterations of synaptic pattern were studied in the molecular layer (ML) of the medial nucleus of the amygdala (MAN) of male and female rats.
As demonstrates the analysis of the data obtained, in male rats the following area respond to gonadectomy: neurons of the anterior amygdaloid area of the dep zone of the anterior cortical nucleus, of the central nucleus, of the posterior intercalated masses, of the dorsomedial nucleus, of the posterior medial nucleus and of the medial part in the posterior cortical nucleus. In female rats anterior parts of the central nucleus, medial and basomedial nuclei at the level of the main trunk in the terminal strip, the dorsomedial nucleus, the periventricular zones, the posterior medial nucleus and the medial part of the posterior cortical nucleus become sensitive to the experimentally produced deficit of the sex hormones.
Additional amygdalopetal connections from the hippocampal region include a previously undescribed projection from the temporal two-thirds of CA1 to the AL and BL and to the posterior cortical nucleus (COp) with the adjacent periamygdaloid cortex (PAC).
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