Biomedical subjects

R Marty

Publications and source records attributed to R Marty.

At least 55 records · Page 3Linked to original sources

PubMed1975

[The Marchi reaction: ultrastructural aspects (author's transl)].

A secondary demyelination process was brought about in the optic tract by unilateral enucleation of 10 adult rats which were sacrificed at 8, 15, 20, 30 and 45 days respectively, after the intervention. The Marchi reaction, which is identifiable by the presence of granular bodies, is positive at all stages, but tends to lessen towards the 45th day. The granular bodies are inside the disintegrating myelin sheath, and gradually fill the space made available by the degenerate axoplasm. The granular bodies are at first bulky and compact before breaking up and disappearing. The remains of the myelin sheath are then resorbed. Satellite cells occur from the 15th day onwards. The interest of the Marchi reaction for the tracing of nervous pathways is confirmed by these findings.

Animals↗

PubMed1975

Postnatal maturation of the cochlear neclei in the cat: a neurophysiological study.

The study of the postnatal maturation of the ventral cochlear nuclei (VCN) and the dorsal cochlear nuclei (DCN) was carried out on the cat by means of recordings of the extra-cellular neuronal activity. At birth it is already possible to obtain toneburst responses in the VCN and DCN. At this age the responses are characterised by a small number of spikes grouped in three bursts when the tone-bursts lasted 500 msec. Subsequently, the number of bursts increases until, from 9 or 10 days onwards the responses become sustained. These responses do not acquire their adult characteristics until more than a month after birth. During postnatal maturation of the cochlear nuclei, the VCN is distinguishable from the DCN by the greater number of units revealing spontaneous activity. Another criterion, such as latency, differentiates the VCN from the DCN from the point of view of the kinetics of maturation.

Animals↗

PubMed1975

[Quantitative study of autoradiographic marking in the rat nervous system. II. Final characteristics of the adult animal brain: interpretation rules and concept of cortical chronoarchitecture].

In this work a statistical study is made of the final outcome of the quantification of the nerve cell labelling in the adult, after prenatal injection of tritiated thymidine. This outcome is presented in the form of histograms which are the superposition of elementary Poisson distributions. A theoretical model, based on Probability theory, has been developed explaining the experimental outcome. Studying the final histograms of a defined region, according to this model, we can find out the number and the importance of the constitutive cell generations (chronology). From the graphic study of the percentage of labelled cells and that of the average of grains, the characteristics of the stratification of the neuronic populations/architectony) can be defined. All these notions have been gathered into a new concept: chronoarchitectony. This concept has also been applied to the neocortex. The results show that there is a strong interpenetration of the different cell generations in a given layer. The cortical neuronic production is a continuous phenomenon and there is no correspondence with the discontinuity of the cortical layers.

Animals↗

PubMed1975

[Chronoarchitectonic analysis of the rat brain using radioautography. I. Histogenesis of the telencephalon].

1) Isocortex We find a centrifugal type chronoarchitectonic gradient with, however, a considerable overlap between the various generations of neurons. Thus in the older, deep layers (13.5 days) of the lateral neocortex 35% of the cells are chromologically incongruous (certain are very recent: 17.5 days and more). Cell production is a continuous process and has its peak towards 15.5 days of gestation. This refutes the existence of successive waves of cells. It is not possible to give even an approximate date to the isocortical layers, for the cortical laminations and the isochrones are nor concentric. What finally characterizes this structure from a chronoarchitectonic point of view is the considerable duration of the sequence of neuron production going from 13,5 days to birth. 2) Allocortex We find a centrifugal gradient in the paleocortex. In several of the structures of which it is composed a chronoarchitectonic incongruity can be attributed to the microneurons. It is the case with the islands of CALLEJA (in the olfactive tubercule) which separate very late on. In the archicortex the dominant gradient is again centrifugal. Here we find horizontal variations of the chronoarchitectonic patterns which are discussed with reference to the conception of a possibly fragmented cortex. 3) Striatum the chronoarchitectonic results largely confirm the diencephalic origin of the paleostriatum (STRASSER 1920, SPATZ 1921). In the archistriatum we find a steep rostrocaudal gradient, while the chronoarchitectonic heterogeneity of the structure tends to confirm the conception of a mixed origin (striatum and paleopallium). 4) Claustrum there is a real chronoarchitectonic incongruity between this structure and the isocortex. On one hand the sequence of the anterior part of the claustrum is of the paleostriate type. The posterior part is more probably archistriate. These findings suggest that the formation of the claustrum is of hybrid origin. 5) Septum The characteristic gradient of this formation is caudorostral. This gradient is practically common to all the structures except the telencephalon. We also find a centrifugal gradient related to the presence of a recent "cortex" which could be the counterpart of the cortical septal nuclei in superior mammals.

Amygdala↗

PubMed1975

[Macrophagic and neuroglial reactions during axonic degeneration following transection of corpus callosum: a radioautographic and ultrastructural study].

The macrophagic and neuroglial reactions occurring in the corpus callosum following transection were studied by radioautography and electron microscopy in adult rats. The animals were killed at intervals ranging from two days to three months after operation. In the lesion itself and the immediately surrounding tissues an important proliferation of hematogenous macrophages was observed. Further away from the point of severance no significant numerical increase in the neuroglia could be noted. However the accumulation of glial filaments, lipid droplets and fragments of myelin sheath in the astrocytes seems to indicate that this type of cell plays a phagocytic role. As for the oligodendrocytes, there is no evidence of their participation in phagocytosis, whereas the microglia plays an important part. In the removal of the tissue debris the role and the origin of the macrophages and the microglia are discussed, as is the share of each type of cell in the phagocytic response depending on the extent of the lesion and the degree of axonal degeneration.

Animals↗

PubMed1975

Comparison of 85Sr, 87mSr, 18F, and 99mTc-labeled phosphates for bone scanning.

The observation by Subramanian and his co-workers that a 99mTc-labeled polyphosphate had excellent affinity for bone has led to widespread use of 99mTc-labeled phosphates as bone scanning agents. Initially, only polyphosphate was employed, but because of somewhat inconstant results and difficulty in preparation of this product, other phosphate compounds were sought. We soon discovered that an inorganic compound, pyrophosphate, appeared to have certain advantages over polyphosphate. Other workers formulated diphosphonates (organic phosphates) which also demonstrated advantages over polyphosphates. Comparison studies in rabbits utilizing 85Sr, 87mSr, 18F, and several phosphates (inorganic and organic) proved the 99mTc-labeled phosphates to be clearly superior in delineating normal skeletal anatomy. Studies in humans confirmed that excellent visualization of bone was obtained with 99mTc-labeled phosphates using either a gamma camera or a rectilinear scanner. What was not known, however, was just how reliable this class of agents would prove to be in detecting bone disease when compared to bone-seeking radiopharmaceuticals such as 85Sr, 87mSr, and 18F. Further comparative analyses have clearly demonstrated that both inorganic and organic 99mTc phosphate complexes are extremely sensitive in revealing more bone disease than the older bone scanning agents.

Adult↗

PubMed1974