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Biomedical subjects

M Berry

Publications and source records attributed to M Berry.

At least 361 records · Page 20Linked to original sources
PubMed1976

The growth of the dendritic trees of Purkinje cells in irradiated agranular cerebellar cortex.

The heads of noenatal Wistar rats were irradiated with 200 rads daily from birth to the 10th day post-partum. Ten litters each containing 5 animals were killed at 30 days post-partum and their brains treated by the Golgi-Cox technique. The dendritic trees of 24 Purkinje cells were analysed using the quantitative technique of network analysis, and comparisons made between parameters obtained from 20 normal Purkinje cells. All dendritic trees in agranular irradiated cortex were markedly reduced in size (as indicated by total dendritic length and total number of segments) although mean path lengths were normal. Segment lengths were normal over proximal branches, but uniformly increased over distal branches. Abnormal appendages, called 'giant spines' were observed on many dendrites. They were often some 10 mum in length and their presence effectively reduced segment lengths, increased the frequency of trichotomy and deviated growth from the normal random terminal pattern so that long collateral branching topologies were formed. Nevertheless, trichotomy was uniformly reduced in those trees without 'giant spines' and the distribution of branching patterns suggested that growth had proceeded by random terminal dichotomy. These results demonstrate that the development of dendritic trees is retarded in the agranular irradiated cerebellum, where synaptogenesis is very greatly reduced below normal. The quantitative changes in segment lengths, size of trees, and trichotomy accord with those predicted by the filopodial synaptogenic hypothesis of dendritic growth formulated by Vaughn et al. 99, whilst the results of the topological analysis suggest that branching is established by a degree of non-random interaction between growing dendrites and their substrate. 'Claw-like' dendritic complexes within some Purkinje cell trees may have been induced by aberrent fibre bundles of few surviving granule cells.

Animals↗
PubMed1976

The growth of the dendritic trees of Purkinje cells in the cerebellum of the rat.

The growth of Purkinje cell dendritic trees in the cerebellum of the rat was studied over the first 50 days of life, using the technique of network analysis and the Golgi-Cox impregnation method. Our findings showed that a growth spurt occurred from the 10th to 30th day post partum (pp) and involved the production of a massive number of branches of fairly constant length. Growth of the tree occurred firstly in the lateral domain, so that by 15 days pp most trees were of adult width. Thereafter, increases in height occurred until 30 days pp. Associated with this change in direction of growth, from the mainly transverse to the vertical plane, was a deviation from the normal random pattern of branching of the tree, but this was reestablished when reorientation was complete, and growth in the vertical plane underway. The lengths of proximal segments increased once they had become established, but distal branches probably maintained a constant length. The above results, together with changes in segment length, trichotomy, branching probability, and growth cone morphology during development have been discussed in relation to current concepts of dendritic growth.

Age Factors↗
PubMed1976

The application of network analysis to the study of branching patterns of large dendritic fields.

Network analysis of dendritic fields not only defines the topology and connectivity of segments of an arborescence, but offers a means of discovering how networks grow. An important theory has recently been formulated29 suggesting that dendritic branching patterns may be established by synaptogenic interaction of dendritic growth cones with growing axons. This thesis may be verified through network analysis since the theory predicts that growth at pendant vertices will predominate in dendritic networks, that dendritic growth will be directed into areas of maximal synaptogenic activity and that arc lengths will be inversely related, and the order of branching at vertices directly related, to the magnitude of the synaptogenic activity operating about growing dendritic terminals. The possibility of a preponderance of terminal growth may be detected by comparing the topologies in an observed dendritic network with those of a series of hypothetical growth models. This paper provides the frequency table for models grown by monochotomous, dichotomous and trichotomous branching on random pendant vertices and random arcs for large networks in which 'set theory' contingencies are included. The paper also describes a method of calculating branching probabilities from the measurement of segment lengths, which is a means of testing the last mentioned prediction of the synaptogenic theory of denddritic growth. The method of network analysis is then discussed in relation to probable dendritic growth patterns, the constancy of segment lengths and the interaction of extrinsic and intrinsic factors in determining branching probabilities.

Dendrites↗
PubMed1976

The effects of reduced climbing and parallel fibre input on Purkinje cell dendritic growth.

The effects of afferent fibre depletion on the development of the dendritic trees of Purkinje cells in the cerbellum were investigated. Parallel fibres were reduced by postnatal administration of a schedule of low level X-irradiation. Climbing fibers were prevented from innervating the cerebellum by lesioning the olivo-cerebellar tract. Network analysis was performed on Purkinje cells in Golgi-Cox preparations of the vermis of 30-day-old animals. tin the irradiated cerebella Purkinje cells with a 'weeping willow' type morphology predominated. Purkinje cells devoid of their climbing fibre contact exhibited large spines on their main dendritic trunks. In both experimental situations the size of the dendritic tree was reduced. This diminution was the result of a decrease in the total number of dendritic segemnts. Individual segment lengths were largely unalteral. Topological type analysis revealed that the trees had arisen in a manner indistinguishable from terminal dichotomous branching and that the 'weep-willow' pattern was produced by a deviation of branching from a purely random form. The interaction of intrinsic and extrinsic factors in the formation of segments and on the nature of branching were discussed.

Animals↗
PubMed1976

Benign lymphoid hyperplasia of the stomach mimicking gastric malignancy.

A case of benign lymphoid hyperplasia of the stomach misdiagnosed as ulcerating gastric carcinoma is presented. The similarities in the clinical, roentgenologic and and gastroscopic features as well as in the gross appearance of the two lesions are described and the features which help differentiation are highlighted. The pathologic picture suggested that the lesion possibly arose as a peptic ulcer and the clinical history further supports such a possibility.

Adult↗
PubMed1975

Network analysis of dendritic fields of pyramidal cells in neocortex and Purkinje cells in the cerebellum of the rat.

The connectivity within the dendritic array of Purkinje cells in the cerebellum and pyramidal cells of the neocortex of the rat, stained by the Golgi-Cox method, has been quantified by the method of network analysis. Connectivity was characterized either by applying the system of Strahler ordering, which assigns a relative order of magnitude to each branch of the arborescence or by the identification of unique topological branching patterns within the tree. The former method has been used to define the entire dendritic array of the Purkinje cell and the apical system of neocortical pyramids. It has been shown that the relation between the numbers of branches of successive Strahler order in Purkinje cells form an inverse geometric series in which the highest order is unity and the ratio between successive orders approximates to 3. On the other hand, the apical dendrites of neocortical pyramids exhibit two bifurcation ratios, i.e. a ratio of 3 between low orders and a ratio of 4 between higher orders. A computer simulation technique was used to generate networks of a size comparable with the Purkinje cell networks and grown according to two hypotheses namely, a 'terminal growth model' in which additional segments were added randomly to the terminal branches only and a 'segmental growth model' in which additional segments were added randomly to any branch within the array including terminal branches. Subsequent ordering of the simulated trees revealed that the relation between the numbers of successive orders for networks generated according to the 'segmental model' tended towards an inverse geometric series with a ratio of 4 and that generated according to the 'terminal model' tended towards a ratio of 3. This result showed that the dendritic tree of Purkinje cells grow in a manner indistinguishable from a system adding branches to random terminal segments and that neocortical apical dendrites add their collateral branches to random segments of the apical shaft but that the collateral branches themselves grow by random terminal branching. The possibility that such conclusions may be influenced by loss of branches incurred by either a failure of impregnation, by sectioning, or by environmental influences was investigated by means of a computer technique...

Animals↗
PubMed1975

Scanning and transmission electron microscope studies of interkinetic nuclear migration in the cerebral vesicles of the rat.

A scanning electron microscope (SEM) was used to examine the morphology and surface texture of neuroepithelial cells during interkinetic nuclear migration in the cerebral vesicles of the rat at 12, 13 and 14 days of gestation. Serial sections of embryonic material of the same age were also prepared for the transmission electron microscope (TEM). Particular attention was paid to the SEM and TEM appearance of mitotic neuroepithelial cells which occur exclusively along the ventricular border of the neural epithelium. Three distinctly-shaped classes of mitotic cells were recognised in scanning micrographs. (1) Pyriform cells. This type of mitotic cell was characterised by the presence of very long, fine processes radiating from the tip and shoulders of a short external (basal) process. These fine processes were termed "intramitotic filopodia." Microvilli were found on the surface of most pyriform cells. (2) Conical cells. These lacked an external process but there were large numbers of intramitotic filopodia at the basal pole of the cell body, and the perikaryal surface was rich in microvilli. (3) Globular cells. It was possible to subdivide this class of cell into large and small sizes, but usually a few short intramitotic filopdia were present at the basal pole. The perikaryal surfaces of the globular population were raised in coarse lumps and bubble-like protrusions. By pooling TEM and SEM information we were able to deduce that pyriform cells probably possess a prophase or prometaphase chromosome morphology, while conical cells exhibit a chromosome morphology somewhere between prometaphase and early anaphase. Large globular mitotic cells were found to be between metaphase and late anaphase and small globular cells were identified as early telophase cells. On the basis of these findings we have proposed that as a bipolar neuroepithelial cell rounds up for mitosis it passes first through a pyriform stage during which the external process is retracted or broken down, and then through a conical stage when the cell consolidates its position on the ventricular surface. Finally, the cell enters a large globular stage before dividing into two small globular telophase cells. It is not known what part, if any, the intramitotic filopodia play in this process of rounding up.

Animals↗
PubMed1975

Incidence of suxamethonium apnoea in patients undergoing E.C.T.

Plasma cholinesterase variants have been examined in blood samples obtained from 23 patients who, after an intravenous injection of suxamethonium 30 mg before e.c.t., had prolonged apnoea. Attempts have been made to screen the relatives of all patients shown to have an unusual plasma cholinesterase. The present study indicates an increased frequency of the fluoride-resistant variants in those psychiatric patients sensitive to suxamethonium.

Apnea↗
PubMed1975

Application of network analysis to the study of the branching patterns of dendritic fields.

The technique of network analysis has been used to define the connectivity and growth of networks generated by monochotomous, dichotomous, and trichotomous branching. The number of distinct topologic branching patterns exhibited by networks with a given number of pendant arcs is defined mathematically; when all types are represented, a complete pendant arc series is formed. The frequency of occurrence of topologic types in these series is unique for a given hypothesis of growth. The growth of the small dendritic arrays such as the basal dendritic fields of neocortical pyramids may be studied by comparing the actual frequency of topologic types with those computed according to given hypotheses. For larger dendritic networks such as those of Purkinje cells in the cerebellum it is only practicable to use the topologic types formed by the peripheral parts of the tree as a basis for comparison. Individual dendritic segments can be ordered sequentially to define their hierarchical arrangement; the frequency of orders in a given network always forms an inverse geometric series. The ratio between orders is called the "bifurcation ratio," and the relationship in a given large series between adjacent orders becomes stabilized to a fixed or "established" bifurcation ratio at the periphery of the tree only. This "established ratio" characterizes the pattern of growth of the network. In the proximal part of the tree the ratio between adjacent orders is unstable and accounts for the variability of the overall bifurcation ratio exhibited by different networks with the same fundamental growth pattern and for the deviation of the overall from the established bifurcation ratio. For a given size of network the overall bifurcation ratio may be similar regardless of the mode of growth. It is concluded that the precise definition of branching structures afforded by network analysis makes this technique well suited for the study of the connectivity, growth, and morphology of dendritic trees.

Computers↗