Home About us Contact
|
Home About us Contact | ||
|
|
||
Dorsal Portion (dorsal + portion)
Selected AbstractsDevelopment of the pons in human fetusesCONGENITAL ANOMALIES, Issue 2 2007Toshihisa Hatta ABSTRACT Morphometric and histological studies of the pons were performed by light microscopy in 28 cases of externally normal human fetuses ranging from 90 to 246 mm in crown-rump length (CRL) and from 13 to 28 weeks of gestation. The brainstems of fetuses were embedded in celloidin or paraffin, and transverse sections were prepared. The pons was divided into two regions at the most ventral margin of the medial lemniscus at the level of the motor trigeminal nucleus. The relationships between the total dorsoventral length, ventral length, and dorsal length of the pons versus CRL and gestational ages were calculated, and empiric formulas were fitted. It was found that the ventral portion increased in size more rapidly than the dorsal portion. The proportion of the ventral portion in the total dorsoventral length was constitutively higher than that of the dorsal portion in the present range of CRL. In the pontine nuclei, from 235 mm in the CRL, some large cells with rich cytoplasm, pale nuclei, and a distinct nucleolus appeared on the dorsal side of the pyramidal tract. According to Weigert stained preparations, the first myelinated fibers in each motor root of the trigeminal, abducent, and facial nerves were recognized at 130,140 mm in CRL and the medial lemniscus at 230,235 mm. [source] The tritocerebrum and the clypeolabrum in mandibulate arthropods: segmental interpretationsACTA ZOOLOGICA, Issue 3 2010Jacques Bitsch Abstract Bitsch, J. and Bitsch, C. 2010. The tritocerebrum and the clypeolabrum in mandibulate arthropods: segmental interpretations. ,Acta Zoologica (Stockholm) 91: 249,266 Different interpretations of the segmental composition of the head in mandibulate arthropods are critically reviewed, with particular focus on three closely associated structures: the tritocerebrum, the stomatogastric nervous system and the clypeolabrum. The main conclusions arising from the different discussions are the following. (1) Each tritocerebral ganglion has a dual composition, clearly discernable in some crustacean and hexapod species, including a dorsal portion connected with the second antennae and a ventral portion connected with the stomatogastric nervous system via the frontal ganglion. (2) The suboesophageal commissure linking the tritocerebral lobes of the two sides, can be wholly ascribed to the tritocerebral segment. (3) The stomatogastric nervous system is a morphologically autonomous system that is not fundamentally affected by head metamerization. (4) The clypeolabrum, the epistome,labrum and the hypostome are regarded as homologous formations. The clypeolabrum represents a fundamental structure of the head probably present in the arthropod ground plan. Its close spatial and developmental association with the stomodeum and its derivative, the stomatogastric nervous system, suggests that it is an anterior outgrowth of the forehead arising from a preoral territory (presegmental acron or protocerebral,ocular region?) and secondarily connected with the tritocerebrum, rather than derived from a pair of reduced appendages. [source] Cardiovascular effects of noradrenaline microinjected into the dorsal periaqueductal gray area of unanaesthetized ratsEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 12 2005Gislaine Garcia Pelosi Abstract The periaqueductal grey area (PAG) is a mesencephalic region that is involved in the modulation of cardiovascular changes associated with behavioural responses. Among the neurotransmitters present in the PAG, noradrenaline (NA) is also known to be involved in central nervous system cardiovascular regulation. In the present study we report the cardiovascular effects of the microinjection of NA into the dorsal portion of the PAG (dPAG) of unanaesthetized rats and the peripheral mechanism involved in their mediation. Injection of NA in the dPAG of unanaesthetized rats evoked a dose-dependent pressor response accompanied by bradycardia. The magnitude of the pressor responses was higher at more rostral sites in the dPAG and decreased when NA was injected into the caudal portion of the dPAG. The responses to NA were markedly reduced in urethane-anaesthetized rats. The pressor response was potentiated by i.v. pretreatment with the ganglion blocker pentolinium and blocked by i.v. pretreatment with the vasopressin antagonist dTyr(CH2)5(Me)AVP. The results suggest that activation of noradrenergic receptors within the dPAG can evoke pressor responses, which are mediated by acute vasopressin release. [source] Changes in NOS protein expression and activity in the rat hippocampus, entorhinal and postrhinal cortices after unilateral electrolytic perirhinal cortex lesionsHIPPOCAMPUS, Issue 5 2003Ping Liu Abstract The integrity of the perirhinal cortex is critical for certain types of learning and memory. One important issue relating to the function of this region is its interaction with other brain areas that play a role in memory processing. This study investigates the time course of changes in activity and protein expression of nitric oxide synthase (NOS), which transforms L -arginine into nitric oxide (NO) and citrulline, in the hippocampus and the entorhinal and postrhinal cortices after unilateral electrolytic lesions of the perirhinal cortex. Electrolytic lesions of the perirhinal cortex resulted in long lasting changes in NOS activity and protein expression in the entorhinal and postrhinal cortices (,2 weeks post-lesion). In contrast, there was a small and transient decrease in nNOS expression (with no change in NOS activity) in the dorsal portion of the hippocampus. iNOS was not expressed in any region examined at any time point. These findings provide the first evidence that electrolytic lesions of the perirhinal cortex can result in long-term neurochemical changes in its anatomically related structures. Given that NO has been implicated in neuroplasticity processes, the interpretation of memory impairments induced by electrolytic lesions of the perirhinal cortex (and possibly, therefore, other brain regions) need to be considered with regard to these findings. Hippocampus 2003;13:561,571. © 2003 Wiley-Liss, Inc. [source] A comparative study of mammalian tracheal mucous glandsJOURNAL OF ANATOMY, Issue 3 2000H. K. CHOI We have compared the distribution, numbers and volume of mucous glands in the tracheas of 11 mammalian species. No glands were present in the rabbit. The mouse only contained glands at the border between the trachea and larynx. In the rat, glands were commonest in the cephalad third of the trachea, but on average were much scarcer than in the larger species. Between species, there was a significant correlation between airway diameter and gland volume per unit surface area, suggesting that the rate of deposition of inhaled particles may increase in large airways. In the ventral portion of the trachea of about half the species, the glands were concentrated between the cartilaginous rings; in others they were evenly distributed over and between the rings. In most species in which the trachealis muscle attached to the internal surface of the cartilaginous rings, the glands were external to the muscle. In all species in which the muscle attached to the external surface of the cartilaginous rings, the glands were internal to the muscle. In the ox, goat, dog and sheep, the volume of glands per unit tracheal surface area was markedly greater in the ventral than the dorsal aspect of the trachea. The reverse was true of the pig. In humans, gland density in the 2 regions was similar. The frequency of gland openings was determined in the ox, goat, pig, dog and sheep tracheas, and ranged from 0.3 per mm2 in the dorsal portion of the sheep trachea to 1.5 per mm2 in the ventral portion of the ox trachea. For these 5 species, the volume of gland acini per unit luminal surface area varied linearly with the numbers of gland openings, with the volume of individual glands being constant at , 120 nl. [source] Select spinal lesions reveal multiple ascending pathways in the rat conveying input from the male genitaliaTHE JOURNAL OF PHYSIOLOGY, Issue 7 2010C. H. Hubscher The specific white matter location of all the spinal pathways conveying penile input to the rostral medulla is not known. Our previous studies using rats demonstrated the loss of low but not high threshold penile inputs to medullary reticular formation (MRF) neurons after acute and chronic dorsal column (DC) lesions of the T8 spinal cord and loss of all penile inputs after lesioning the dorsal three-fifths of the cord. In the present study, select T8 lesions were made and terminal electrophysiological recordings were performed 45,60 days later in a limited portion of the nucleus reticularis gigantocellularis (Gi) and Gi pars alpha. Lesions included subtotal dorsal hemisections that spared only the lateral half of the dorsal portion of the lateral funiculus on one side, dorsal and over-dorsal hemisections, and subtotal transections that spared predominantly just the ventromedial white matter. Electrophysiological data for 448 single unit recordings obtained from 32 urethane-anaesthetized rats, when analysed in groups based upon histological lesion reconstructions, revealed (1) ascending bilateral projections in the dorsal, dorsolateral and ventrolateral white matter of the spinal cord conveying information from the male external genitalia to MRF, and (2) ascending bilateral projections in the ventrolateral white matter conveying information from the pelvic visceral organs (bladder, descending colon, urethra) to MRF. Multiple spinal pathways from the penis to the MRF may correspond to different functions, including those processing affective/pleasure/motivational, nociception, and mating-specific (such as for erection and ejaculation) inputs. [source] A New Sauropod Dinosaur from the Late Cretaceous Gaogou Formation of Nanyang, Henan ProvinceACTA GEOLOGICA SINICA (ENGLISH EDITION), Issue 2 2009Xingliao ZHANG Abstract: A new sauropod dinosaur Baotianmansaurus henanensis gen. et sp. nov. from the Cretaceous Gaogou Formation of Neixiang, Henan Province is erected. It is characterized by somphospondylous presacral vertebrae; a highly-developed lamina system on the dorsal vertebrae; transverse process supported by four laminae; and the dorsal portion of the anterior centroparapophyseal lamina is bifurcated, with a small branch extending to the ventral surface of the prezygapophysis. It represents a new titanosauriform sauropod. [source] Projections from the hippocampal region to the mammillary bodies in macaque monkeysEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 10 2005John P. Aggleton Abstract A combination of anterograde and retrograde tracers mapped the direct hippocampal and parahippocampal inputs to the mammillary bodies in two species of macaque monkey. Dense projections arose from pyramidal cells in layer III of the subiculum and prosubiculum, and terminated in the medial mammillary nucleus. While there was no evidence of an input from the dentate gyrus or fields CA1,3, a small contribution arose from the presubiculum and entorhinal cortices. All of the hippocampal and parahippocampal projections to the mammillary bodies appeared to use the fornix as a route. The caudal portions of the subiculum and prosubiculum contained the greatest numbers of cells projecting to the mammillary bodies. A light contralateral projection to the medial mammillary nucleus was also observed, although this appeared to arise primarily from the more rostral portions of the subiculum and prosubiculum. There was a crude topography within the medial mammillary nucleus, with the caudal subicular projections terminating in the mid and dorsal portions of the nucleus while the rostral subicular and entorhinal projections terminated in the ventral and lateral portions of the medial nucleus. Light ipsilateral projections throughout the lateral mammillary nucleus were sometimes observed. Comparisons with related studies of the macaque brain showed that the dense hippocampal projections to the mammillary bodies arise from a population of subicular cells separate from those that project to the anterior thalamic nuclei, even though the major output from the mammillary bodies is to the anterior thalamic nuclei. Other comparisons revealed underlying similarities with the corresponding projections in the rat brain. [source] | ||||||||||||||||||||||