The ontogeny of fluctuating asymmetry

We tested seven hypotheses regarding the mechanisms by which fluctuating asymmetry (FA) originates. We did this by analyzing data on four bilateral characters measured repeatedly during the development of individual domestic fowl. Immediately posthatching, there was substantial directional asymmetry, which rapidly decreased. We detected FA at significant levels in all characters in the majority of our measurements over the remainder of development. We also examined the effects of known environmental stressors (food and density stress) on levels of FA. At the levels we examined, changes in these stressors did not alter the degree of asymmetry we found in fowl. Time series of asymmetry for individuals did not exhibit regular oscillations, as much of the relevant literature predicts. Asymmetry levels reflected the combined effects of developmental noise, which was random in degree and direction, and feedback processes, which decreased asymmetry by altering growth rates on both sides of the body. Our findings best fit the predictions of the residual asymmetry and compensatory growth hypotheses, which suggest that levels of asymmetry reflect only recent growth history.     

The role of individual characteristics and learning in the manifestation of motor asymmetry in rats

Relative role was studied of the initial preference (caused by animals individual properties) and learning in real preference of one limb in rats. After a short-time learning to get food from a narrow horizontal pipe only by the left paw a retrograde amnesia was evoked in rats. At preference determination after three weeks, in conditions which allowed to get food by any paw, in the group of animals without amnesia the number of the left-handed rats was 5.7 times more than of the right-handed ones. In the group of animals with amnesia the numbers of the left-handed, right-handed and ambidextrous were approximately equal. Correlation was revealed between the speed of learning to get food by the left paw and the number of attempts to use the right paw. It has been shown that the initial preference may be stably changed even by a short-time learning (3 food seizures). By the degree of manifestation of the initial preference the rats form a continuum with a gradual transition from pronounced right-handed animals to pronounced left-handed ones. The weaker is the initial preference, the greater the role of learning in the real preference of one of the paws.     

The formation of interhemispheric asymmetry in human ontogeny during the perception of emotions in normal speech and in stuttering]

Age peculiarities of functional brain asymmetry in perception of emotional information of speech have been revealed. It was shown that the age of 4-7 years is most important for formation of this asymmetry in emotional perception. It is in this age that functional reorganization of perception in stuttering children is observed. These data indicate that correction of emotional activity in stutterers should be made at early periods of their life.     

Morphometric and histochemical characteristics of the frog sartorius muscle in ontogeny]

Morphometric and histochemical investigation of musculus sartorius was performed in ontogenesis in Rana ridibunda and Rana temporaria. Muscular composition was characterized according to the type of muscular fibres. Spectrum of lactatdehydrogenase isoenzymes was studied at different developmental stages. As the studies demonstrated, musculus sartorius underwent some essential changes in ontogenesis which manifested themselves in increasing number of muscular fibres and their areas, in changing LDG isoenzymic spectrum. Differentiation of the muscular fibres three types takes place at the 30th stage after P. V. Terentiev and depends on the nerve system maturation.     

The characteristics of motor asymmetry in rats with genetic epilepsy (the WAG/Rij strain)]

Motor asymmetry was studied in two groups of WAG/Rij rats with genetic absence epilepsy. A rat had to get food from the horizontal tube with preferable forelimb. The asymmetry coefficient Cas was calculated for the first 10, 50, and 100 trials. In the first group ("pure" absence epilepsy, n = 34) the percent of "left-handers", "right-handers", and ambidextrous calculated for the first 10 trials, was 56, 26, and 18, respectively. In the second group (mixed form of epilepsy, n = 27) this ratio was 19, 40, and 41%, respectively. The percent of ambidextrous, calculated for 50 and 100 trials, substantially decreased in both groups, and the above mentioned ratio became 62, 32, and 6% in the first group and 30, 63, and 7% in the second one. A possible association of pathogenesis of different forms of epilepsy with forelimb preference is discussed.     

The organizational characteristics of the APUD system in mammalian lungs at different stages of ontogeny]

The organization peculiarities of APUD-system in the lungs of rabbits, rats and guinea pigs has been studied. The endocrine system in the lungs of rabbits in pre- and postnatal ontogenesis is presented by the adipocytes and neuroepithelial bodies (NEB) containing a considerable number of monoamines. The number of argyrophil adipocytes and NEBs in the lungs of 21 and more day-old adult rats seem to be less than in fetuses and newborns. Monoamines are not revealed in the endocrine rat lung structures by means of the glyoxylic acid. In the lungs of guinea pigs the single argyrophil adipocytes and NEBs are determined in the gestation period.     

Lack of limb motor asymmetry in the neonate

Neonates were examined for evidence of lateralization of motor function. The stepping test was done and the foot that moved first was recorded. The reaction of both arms to avoid an obstacle was also tested. No evidence for lateralization was found. Previous studies in the neonate have shown asymmetry of anatomical structures subserving language, and functional asymmetry of auditory functions and head position. However, the development of limb handedness occurs only at a later age.     

The major proteins of the human myocardium in ontogeny]

Two-dimensional electrophoresis according to O'Farrell was used for studying changes in the content of major proteins of human myocardium at various stages of pre- and postnatal development. On the basis of the protein pattern specific of certain stages of myocardium differentiation the degree of development of the human cardiac muscle can be determined. The most pronounced changes in myocardium protein spectra are characteristic of the first half of pregnancy.     

On the ontogeny of the motor circadian rhythm in crayfish

In this paper we attack the problem of understanding the localization of the main structures involved in the motor circadian rhythm of crayfish by analysing its ontogeny. We present experimental results giving the properties of this rhythm in young and adult crayfish. Then we construct a mathematical model (based on a previous one for the electroretinogram circadian rhythm in the same species) simulating those properties. In the process of constructing the model we clarified and made precise various hypotheses about the biological structures involved in them and about the characteristics of the oscillators present in those structures. We also formulate some hypotheses about the general properties of circadian rhythms. Finally, we propose some experiments suggested by the mathematical model.     

The characteristics of the hormonal profile of the central links in the regulation of adrenocortical function in rat postnatal ontogeny]

Radioimmune assay has been made of the ACTH content of the blood and adenohypophysis, as well as the content of vasopressin in the blood, median eminence, the posterior and intermediate hypophysis in 1, 3, 5, 7, and 20 days old rats and adult male rats. Comparison of the hormonal level in neurohaemal areas with that in the blood plasma suggests that transadenohypophyseal path of hypothalamic neurohormonal control of the adrenocortical function becomes essentially important only after formation of capillary plexus in the external zone of the median eminence.     

The anatomicohistological characteristics of the formation of the mucosa of the human small intestine in the prenatal period of ontogeny]

The time, when the first villi appear, is defined. Quantitative composition, percent content, height of the villi of the mucous membrane in all parts of the small intestine during various periods of the intrauterine development are presented. In 17-week-old embryos at the level of the duodenum the first villi are noted and their formation in the middle part of the intestinal tube is revealed. By the 8th-9th weeks of development they appear at the level of the caudal part of the intestine. This demonstrates asynchronism of their formation in the cranio-caudal direction. The periods of their intensive growth in height in the first part of the intestine correspond to 8-10, 12-16, 24 weeks of the fetus age, in the second part--to 8-10, 18-20 weeks, in the third--to 10-12, 16-18, 26-28 weeks. These periods alternate with an abatement in growth intensity, which is connected with an increasing width of the villi themselves, with amount of newly formed villi and with changes of the intestinal tube diameter. The form of the villi is rather variable.     

The developmental patterns of the cartilaginous elements in vertebrate ontogeny]

Comparative embryological data presented in the paper support an idea that chondrification of the mesenchyme does not begin until the latter becomes condensated. Size and density of the skeletogenous rudiments are not the same in different vertebrates. As a rule, in animals with much of the mesenchyme (chondrichthyans, amniotes), the prochondral condensations contain more cells and have both greater mass and density. The distribution pattern of the mesenchyme is also significant for the future development of the cartilaginous elements which at the earlier stages grow largely by the recruitment of surrounding mesenchymal cells. Such kind of the growth mode is probably most similar to the cartilage fusion mode: both processed take place in the absence of the perichondrium. The non-skeletal dense structures influence on the development of the cartilaginous skeleton primarily by determining distribution pattern of the mesenchyme, particularly the condensation of skeletogenous cells. THe growing cartilages themselves can influence mechanically on the surrounding organs.     

Rotational stimulation-related changes of the motor asymmetry in the goldfish

We studied changes in the motor asymmetry of the goldfish induced by single-session long-lasting vestibular stimulations (clockwise and counter clockwise rotations around the rostro-caudal body axis) and repetitive everyday short sessions of such stimulation (training); the latter mode led to the development of adaptation (resistance to fatigue). Rotational stimulation of different durations and directions elicited effects of different patterns and intensities. Such stimulation enhanced or, vice versa, smoothed the motor asymmetry in “dextral” and “ sinistral” fishes, up to full symmetry or even a change of the preferred turning direction. Adaptation to unilateral rotational stimulation allows an experimenter to selectively and gradually induce the resistivity of the left-or right-ward asymmetry to fatigue effects. Earlier, we found that the motor asymmetry in the goldfish, which is determined by the functional asymmetry of the brain, correlates with the morphological asymmetry of Mauthner neurons localized in the medulla in a mirror manner and playing a crucial role in the control of turnings in the course of locomotion (swimming). Experimental rotational stimulation-induced gradual modification of the motor asymmetry in the goldfish can serve as a physiological model for more detailed studies of the structural base of the functional brain asymmetry and some mechanisms of adaptation on the level of single neurons. Neirofiziologiya/Neurophysiology, Vol. 37, Nos. 5/6, pp. 432–442, September–December, 2005.     

Interhemispheric motor asymmetry of conditioned feedback

The interhemispheric asymmetry and lateralization of motor functions, as applied to backward conditioning, was studied in two dogs that afterwards turned to be a right-hander and a left-hander. In the process of food-procuring instrumental conditioning it was revealed that one of the dogs predominantly used the right paw (with the dominance of the left hemisphere) and the second animal used the left paw (the right brain hemisphere dominated). The earliest signs of lateralization of the motor functions were observed in the backward conditioned connections (which had been formed earlier than the direct connections or direct conditioned reflexes). Consequently, the presence and sign of asymmetry can be predicted on the basis of manifestation of the backward connections observed at the early stages of acquisition of food-procuring behavior. The backward connections are strictly specific and have the same lateralization as the direct ones.     

The morphochemical characteristics of the brain in Wistar rats that differ by open-field motor activity]

By cytochemical and biochemical methods it is established that in rats with low motor activity the increased content of proteins of cytoplasma and nuclei of neurones of the sensorimotor cortex, caudate nucleus and n. accumbens, the increased activity of a number enzymes of oxidizing and protein metabolism in them are combined with a low activity of enzymes of mediator exchange. In the studied formations in rats with high motor activity an increased activity of synaptic and membrane forms of acetylcholinesterase appears at the same level of activity of cholineacetyltransferase in these subcortical formations and at high monoamineoxidase activity in cellular structures of the cortex and in subcortical formations. It is shown that in animals of the same line but differing by the behaviour in the open field, brain formations such as the sensorimotor cortex, caudate nucleus and n. accumbens have their own biochemical properties of the studied characteristics.