Biomedical subjects

G Amat-Peral

Publications and source records attributed to G Amat-Peral.

4 recordsLinked to original sources

PubMed1999

Lateral evaginations from the third ventricle into the rat mediobasal hypothalamus: an amplification of the ventricular route.

In this work we report the existence of several evaginations extending out of the third ventricle within the mediobasal hypothalamus of the rat. In coronal sections, these evaginations appear as very narrow canaliculi integrating a canalicular system, which increases the contact surface between the ventricular lining and the nervous tissue. Consequently these evaginations enlarge the ventricular route for the transport of active principles present in the cerebrospinal fluid, such as (neuro)hormones and neurotransmitters. The mediobasal hypothalamus includes the arcuate nucleus and the median eminence (both involved in neuroendocrine mechanisms and in the regulation of pituitary function). A possible implication of our finding is that the neuroactive substance-containing ventricular cerebrospinal fluid may reach the intercellular spaces of the surrounding neuropil of the arcuate nucleus. According to literature these substances cross the ependyma of the lateral wall of the infundibular recess of the third ventricle. We suggest that such substances might also pass through the ependymal lining of the canalicular system, which displays the same ultrastructural characteristics as the rest of the ependyma of the lateral wall of the third ventricle. Therefore, the arcuate neurons may be influenced not only by synaptic inputs (afferent fibers) but also by non-synaptic diffusion neurotransmission (by means of neuroactive substances present in the cerebrospinal fluid).

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PubMed1995

Giant granular filamentous bodies in the cytoplasm of arcuate nucleus neurons of castrated rats.

We have performed an ultrastructural and quantitative study of granular filamentous bodies (GFBs) present in the cytoplasm of some arcuate nucleus neurons of rats of both sexes castrated at one month of age and sacrificed one or three months later, as well as untreated and sham-operated animals of the same ages. GFBs appear as round or ovoid cytoplasmic inclusions of granular-filamentous texture and generally lack a limiting membrane; their sizes vary from 0.7 to 2.8 microns (average 1.7 microns). GFBs are present more frequently in the perikarya, but they also occur in dendrites. In rats of both sexes castrated at one month of age and sacrificed three months later a noticeable finding was the presence of some giant GFBs, whose major axis could reach up to 6 microns. The nomenclature, the origin and the possible significance and function of GFBs are discussed.

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PubMed1994

Transependymal diapedesis: reality or speculation?

The present study attempts to describe the possible origin of certain elements situated inside the infundibular recess of the third ventricle, such as supraependymal cells and Herring bodies, together with the way in which they reach the ventricular lumen. We used albino Sprague-Dawley rats and cats of both sexes sacrificed at different ages. The results point to the possible existence of a transependymal diapedesis of some Herring bodies and supraependymal cells into the infundibular recess.

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PubMed1992

[Morphologic substrates of the ventricular route of secretion and transport of substances in the tubero-infundibular region of the hypothalamus. Ultrastructural study].

Ultrastructural studies of the ependyma of the tuberoinfundibular region of the rat hypothalamus have revealed the existence of intraventricular axonal endings and of cytoplasmic blebs and bulbs that project from the apical surface of the ependymal cells to the ventricular lumen. All these structures account for the processes of ependymal apocrine secretion and the neuroventriculocrinia, and hence the release of biologically active substances into the cerebrospinal fluid (CSF). These substances contained in the CSF must act on the nervous nuclei of the tuberoinfundibular region, such as the arcuate nucleus, which is very important in the neuroendocrine regulation of the anterior pituitary gland. Dilated intercellular spaces among neighbouring ependymocytes of this region, small intraependymal cisternae and, in particular, a lateral prolongation of the infundibular recess, which courses through the nervous tissue between the arcuate nucleus and the median eminence from the vertex of the lateral angle of the infundibular recess, may be the route followed by the CSF from the third ventricle to the tissue compartment of the tuberoinfundibular region. Also studied are the cisternae of the region and the relationships of these with the lateral prolongation of the infundibular recess. Some of these cisternae may be filled by the CSF through the prolongation. In this way, the tissue compartment of CSF would be enlarged, and hence the ventricular route for the secretion and transport of biologically active substances would be potentiated.

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