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Several evidences suggest that the posterodorsal medial amygdala (MePD) can be a relevant part of the rat neural circuitry for the regulation of hypothalamic neuroendocrine secretion and for ontogenetically different behavioral displays. The dendritic spine density of Golgi-impregnated neurons from the MePD was evaluated in young rats following acute or chronic restraint stress and in aged animals (24 months old). Compared to the control group, a single 1 h restraint stress session promoted a decreased spine density (p<0.01) whereas a single 6 h restraint stress session or daily 6-h restraint sessions for 28 consecutive days did not lead to the same effect (p>0.05). Aged rats showed no difference in this dendritic spine parameter when compared to young adults (p>0.05). These results indicate that short-term stress (1 h) can affect MePD dendritic spines and that neural plasticity is involved with adaptive responses onwards in restrained rats. On the other hand, brain structural modifications related with ageing appear not to influence the number of certain postsynaptic sites in the MePD of rats.

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Electron microscopy of the lungs of Melanophryniscus stelzneri stelzneri (Anura) revealed the presence of a complex pattern of corpuscular cells (CCs). The respiratory surface over the septa presents small areas where the CCs are grouped forming neuroepithelial bodies (NEBs). These corpuscular structures can also be localized in the inner layer of the lung wall. Although in both cases NEBs protrude slightly into the airway lumen, they are separated from the airway lumen and the basal connective tissue by thin apical and basal cytoplasmic processes of neighbouring pneumocytes. Ultrastructurally, the CCs possess a large nucleus, clear cytoplasm and vesicles of variable morphology and size, containing an electron dense material surrounded by a lucent space in some cases. The size of these dense-core vesicles (DCVs) ranged from 40 to 100 nm. The NEBs are associated with afferent and efferent terminal nerves. These types of nerve endings are located between the CCs and in the basal part of the NEBs. The location of the NEBs in strategic positions on the septa and in the wall of the lung, the presence of the DCVs in the basolateral region of the CCs, the occurrence of synaptic contacts between nerve endings and the CCs and the occurrence of capillaries close to the NEBs, suggest a receptosecretory function for NEBs in the lung of M.s. stelzneri.

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OBJECTIVE: The urethra is the main port of entry of sexually transmitted pathogens. However, papers on the morphology of the urethra are scarce. The Mongolian gerbil is a rodent native of the Mongolia and China and has been utilized as a laboratory animal since the 1960s. This work describes the ultrastructure of the urethra of the Mongolian gerbil to provide data for future experimental studies. METHODS: The urethra of ten adult male gerbils was studied by transmission electron microscopy. RESULTS: The epithelium of the pelvic urethra possesses two cell types: I and II, without the formation of cellular layers, while the penile urethra possesses cellular layers: basal, intermediate and superficial. The urethra presents neurosecretory cells belonging to the amine precursor uptake and decarboxylation system. CONCLUSIONS: The urethral epithelium of the gerbil is a neurosecretory epithelium, part of the amine precursor uptake and decarboxylation system.

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A conglomerate of 8-12 neurons in the medulla externa of the crayfish eyestalk was explored in their reaction to a polyclonal antibody against the tyrosinated octapeptide Red Pigment Concentrating Hormone (Tyr-RPCH). These are large neurons with diameters within a range of 33-43 microns and they were all positively stained with neutral red. By intracellular staining with lucifer yellow, the neurons were found to branch extensively within the medulla externa and the lamina ganglionaris of the eyestalk. Each neurite bifurcates at about 40 microns from the soma. Both branches run to the medial edge of the eyestalk; one proceeds distally to the lamina ganglionaris, while the other runs proximally to the medulla interna. Both end freely in multiple arborizations, covering from the medial to the lateral edges of the eyestalk. No branches were found to the sinus gland, the main neurohaemal organ of the eyestalk. A group of 4 neurons in the conglomerate consistently rendered positive reaction to the anti-Tyr-RPCH antibody (A-RPCH). They are superficially located in the cluster, and at the electron microscope, they showed the usual features of a secretory cell, i.e., clear and dense granules, an active and well-developed Golgi apparatus, and rough endoplasmic reticulum. The dense granules were larger (mean diameter: 101.5 nm) than the clear granules (mean diameter: 90.3 nm). The immunopositive reaction at the electron microscope was found to be largely confined to the dense-cored granules.

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Se postula el envejecimiento como un proceso regulado por la glándula pineal a través de mediadores hormonales que en la vejez inducen degeneración dentrítica y de la relación entre los diversos sentidos y el sistema nervioso central. Es revisada la disminución en la actividad catecolaminérgica hipotalámica, las variaciones en la hormona del crecimiento, prolactina, hormona antidiurética, y de igual manera la relación del sistema neuroendocrino y otros sistemas como el inmune, adrenal, tiroideo y gonadal con énfasis en el cambio del ritmo circadiamo

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Las neoplasias neuroendocrinas de laringe son estidades poco frecuentes. Estos tumores presentarn una amplia gama de características histiológicas que abarcan desde el típico carcinoma hasta los poco diferenciados carcinomas de células pequeñas. Su comportamiento se correlaciona con el subtipo histopatológico. El tratamiento central en los casos tempranos es la resección quirúrgica. La quimioterapia y la radioterapia no tienen un papel efectivó en el manejo de estas neoplasias. Exponemos el caso de un hombre de 64 años de edad que presentaba disfonía progresiva con cuatro meses de evolución. El examen físico y la laringoscopia evidenciaron un tumor supraglótico vegetante que afectaba el seno piriforme y se extiendía hasta la retrofaringe. Fue tratado con cirúgia radical; varias semanas después de ésta, se perdió de seguimiento sin actividad tumoral. Además del caso clínico, se comentan diversas consideraciones sobre los carcinomas neuroendocrinos.

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The pineal complex of larval Geotria australis lampreys has been examined by light- and electron-microscopy. The complex consists of a pineal organ and a smaller parapineal organ, the former being situated dorsal to the latter. It is concluded that the pineal organ is a functioning photoreceptor, with neural and endocrine output. The parapineal appears to be a more basic neuroendocrine organ without photosensory capability. Day-night comparisons of the pineal complex show no obvious differences in ultrastructure; this could be related to the chronobiological role of the complex as a constant monitor of ambient light levels, rather than a mere visual receptor that changes its sensitivity at night.

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Neuroepithelial endocrine (NEE) cells were for the first time identified in the lung of the entirely aquatic urodele, Ambystoma mexicanum, by using light and electron microscopy, histochemistry, and immunocytochemistry. In the basal part of the ciliated epithelium and, less often, in the respiratory portion of the lung, NEE cells were found to occur both solitarily and in small clusters. No typical neuroepithelial bodies could be found. Using the method of Fernandez Pascual, some NEE cells were found to be argyrophilic. Microspectrofluorimetric analysis of formaldehyde-induced fluorescence and immunocytochemistry revealed the presence of 5-hydroxytryptamine. With antibodies to neuron-specific enolase only a few NEE cells exhibited a faint immunostaining. Electron-microscopically, the NEE cells are provided with distinctive cytoplasmic membrane-bound dense granules of variable size, which gave a positive argentaffin reaction. The images of emiocytotic granule release are indicative of a secretory function. In the tracheal epithelium. NEE cells seem to occur only solitarily. They bear the same ultrastructural characteristics as the intrapulmonary NEE cells but here, the dense granules are larger and associated with numerous bundles of microfilaments. Intraepithelial nerve endings were observed near the airway lumen. Between nerve terminals and NEE cells, synaptic complexes with aggregations of clear-centered vesicles close to the presynaptic membrane thickenings were observed. In addition, some nerve endings from "reciprocal synapses" with NEE cells. A receptosecretory function for NEE cells in the lung of A. mexicanum is supposed.

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Em P. megistus o corpus cardiacum e a aorta têm uma estrutura semelhante. Ambos apresentam axônios de neurônios secretores cerebrais. A presença de grânulos de neurossecreçäo e o revestimento por uma bainha conjuntiva reforçam a idéia da funçäo neurohemal da aorta. O corpus allatum mostra células de formas diferentes. Os núcleos säo volumosos e muitos deles têm nucléolos desenvolvidos. Numerosas mitocôndrias granulares e filamentosas säo vistas concentradas em determinadas regiöes das células. Os contornos das células e dos núcleos säo regulares, características de células do corpus allatum ativo

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