Dissymmetry of the origins of the roots of the spinal cord in the dog

The spinal cord in 25 non-inbred dogs has been studied macro-microscopically. The dissymmetry in the arrangement level in the right and left root bases on the dorsal surface of the spinal cord is much greater than on the ventral surface. The same as in the human being, the dissymmetry is the greatest in the thoracic part (as compared to other spinal parts). On the ventral surface of the spinal cord both along the anterior and posterior margin of the root bases, there is a right-sided dissymmetry (with cranial shift); on the dorsal surface it is present only at the roots along the posterior margin. The dissymmetry of the dog spinal cord is quantitatively estimated along its whole extension.     

Individual variability in the structure of the walls of the principal trunks of the subcutaneous veins of the lower extremities of the human fetus

Certain regional peculiarities are noted in the development process of the human principle trunks of the subcutaneous veins during antenatal period. In the fetuses of all ages the wall thickness of the subcutaneous veins is the greatest in the femur, and the middle tunic is better developed in the shin. The vein structure depends on the type of architectonics: at the magistral type (86%) the walls in the large and minor subcutaneous veins are thick with well developed smooth myocytes and connective tissue fibers; at the reticulate type (14%) the walls are thin, their elements are poorly developed. When there is mentioned varicosity of the lower extremity veins in the parents' anamnesis, in fetuses (57%) all the tunics in the venous wall develop more poorly, there is retardation in formation of smooth myocytes and in maturation of collagen fibers. This results in less amount of contractile structures in the middle tunic and optic density of collagen is less manifected.     

On the nature of the horny scales of the pangolin

The pangolin scale is a horny derivative of the epidermis. It is complex in structure and is divisible into three distinct regions. The dorsal plate forms approximately one-sixth of the scale thickness. It is composed of flattened solid keratinized cells without basophilic nuclear remnants. This region tends to fray easily. The dorsal plate contains bound phospholipids and sulphydryl groups but is weak in disulphide bonds.
The bulk of the scale is made up of the intermediate plate formed of less flattened cells without basophilic nuclei. This region is rich in disulphide bonds but contains no appreciable bound phospholipids or sulphydryl groups.
The ventral plate is only a few cells thick and is rich in bound phospholipids, which also occur in the underlying scale bed epidermis.
These three regions of the scale are formed from separate epidermal germinal areas which do not develop a granular layer. Keratohyalin granules are, however, formed in the epidermis between the scales.
It is suggested on the basis of histological structure and dishribution of chemical constituents that pangolin scales are probably homologous with primate nails.
Evidence against the views that they are homologous with reptilian scales or are derived from compressed hairs is presented.     

Characteristics of the membranes of the pellicle of the ciliatePseudomicrothorax dubius

Summary The membranes of the pellicle of the ciliatePseudomicrothorax dubius are investigated using thin section electron microscopy and freeze-fracture replicas. The plasma membrane is covered by a surface coat and is connected to the outer alveolar membrane by short, sometimes branched, bridges. The inner alveolar membrane is coated on both sides. The epiplasm lies in intimate contact with the cytoplasmic surface of this membrane, and there is a corresponding deposit on the other surface. This deposit is regularly striated.The epiplasmic layer and the alveoli are interrupted at sites of cytotic activity,e.g., the attachment sites of trichocysts, the cytoproct, and the parasomal sacs. The striated deposit ends where the epiplasm ends, indicating a direct relationship between these two epimembranous layers.There is a deposit along the sides of the first part of the tip of the trichocysts, and in this region the trichocyst membrane is free of intramembranous particles.The membrane of the parasomal sacs has a coat on both surfaces. That on the extraplasmic surface is similar to the surface coat of the plasma membrane. The origin of the cytoplasmic coat is unknown. The cytotic activity of these sacs is indicated by their highly irregular profiles.     

On the origin of the genetic code and the stability of the translation apparatus

An “error theory” is developed which can be applied to determine the stability of a macromolecular translation machinery which reproduces itself. It is shown that the overall effects of a multitude of possible error versions of macromolecules can be treated statistically, and that such a statistical approach is of considerable usefulness in the theoretical treatment of complex macromolecular systems. The theory is developed within the context of a detailed treatment of the “frozen accident” hypothesis for the origin of the genetic code. A model is described which permits some thermodynamic characterization of the components involved in the code nucleation. The model also proves useful in resolving a stability “paradox” described by Orgel, which relates to the translation stability in present-day organisms and mechanisms of ageing. It indicates that any experimentally found decrease in translation accuracy with age is probably not due to an inherent instability in the translation apparatus. Relevant experiments are suggested.     

Tracking in the Wlds--the hunting of the SIRT and the luring of the Draper

Wallerian degeneration of distal axons after nerve injury is significantly delayed in the Wlds mutant mouse. The Wlds protein is a fusion of nicotinamide mononucleotide adenyltransferase-1 (Nmnat1), an essential enzyme in the biosynthesis pathway of nicotinamide adenine dinucleotide (NAD), with the N-terminal 70 amino acids of the Ube4b ubiquitination assembly factor. The mechanism of Wlds action is still enigmatic, although recent efforts suggest that it is indirect and requires sequences flanking or linking the two fused open reading frames. Three papers in this issue of Neuron now show that Wlds action is conserved in Drosophila and that a critical role of Wlds may be the suppression of axonal self-destruct signals that induce Draper-mediated clearance of damaged axons by glial cells.     

Localization of the gene of the glyceraldehyde 3 phosphate dehydrogenase on the distal segment of the short arm of the chromosome 12]

The enzymatic activity of G3PD and LDH-B in erythrocytes has been assayed in three patients carrying a rearrangement of the short arm of chromosome 12. The first patient is trisomic for the whole short arm. The second is trisomic only for the distal part and the third is monosomic for the proximal part. G3PD: Activity increased in patients 1 and 2 and normal in patient 3. LDH-B: Activity increased in patients 1 and 2 and decreased in patient 3. From these observations it is concluded that the erythrocytic G3PD locus is localized on the distal part of 12p, between 12p12.2 and 12 pter, and that LDH-B locus is on the middle third between 12p12.1 and 12p12.2     

Structure of the mammillary bodies of the hypothalamus of the bottlenosed dolphin

In the bottlenosed dolphin (Tursiops truncatus) the hypothalamic corpus mammillaris has been studied using interperpendicular, sagittal, frontal and horizontal serial sections, impregnated in silver and stained with cresil-violet. Comparatively small dimentions of the corpora mammillaria in the bottlenosed dolphin are explained by presence of only two nuclei, medial and lateral. The lateral nucleus is nearly three times as large as the medial one. The size of the neurons in the medial nucleus is on the average two times as large as that of neurons in the lateral nucleus. The density of the neural cells distribution is a little greater in the lateral nucleus. The structure of the bottlenosed dolphin corpora mammillaria is compared with similar structures in other animals and the human being.     

Reflection in the electrical activity of the brain of the activities of the mechanisms regulating the functional state

On the basis of analysis of the results of author's studies and literature data, theoretical notions are developed, according to which spatial-temporal organization of cortical biopotentials is a result of activity of nonspecific different level systems subtly regulating current alertness in conformity with needs of the actual and forthcoming activities. In the hierarchy of regulating systems, in conditions of alertness, nonspecific thalamic and midbrain system is leading. Activity of these regulation levels provides in alertness for formation and destruction of functional neuronal ensembles which realize elementary informational transformations. The role is emphasized of asynchronous processes in the central nervous system activity.     

Characteristics of the structure of the cornea of the reptilian eye]

Submicroscopic structural peculiarities in the cornea are described in some reptiles (grass-snake, lizard, turtle). Certain stages in histogenesis of the grass-snake cornea are presented. Poor differentiation of epithelium and its resemblance to endothelium is demonstrated in the grass-snake cornea. In cytoplasm of cornea cells of lizard and turtle a high content of mitochondria is noted. Great majority of mitochondria compactly arranged in the middle part of cytoplasm provide the appearance of zones. There is a middle zone of mitochondrial arrangement, there are also two zones in cytoplasm (internal-perinuclear and peripheral) without mitochondria but with supporting structures.     

Ultrastructure of the kidney of the newt

In the newt [Triturus vulgaris (J.)] kidney a zone of single nephrons is distinguished, where there are ten nephrons, connected with the paramesonephral (Müller's) canal, and another zone of the renal mass; in the latter the main part of nephrons is situated, which are connected with the ureter by means of collecting tubules. In these zones of the kidney ultrastructure of epitheliocytes in the proximal and distal parts is different. The renal corpuscles of the epithelial cell in the cervical and in the intermediate parts are similar in both zones. In the zone of the single nephrons a specific peculiarity of epitheliocytes in the proximal and in the distal parts of the canaliculi is presence of numerous secretory granules in their cytoplasm. The canalicular epitheliocytes in the renal mass zone are different in the terminal and in the initial parts of the canaliculi: the former contains more mitochondria, and the area of the basolateral parts of plasmolemma is greater than those in the latter. These results are in accordance with the level of sodium ions transport in these parts of the canaliculus.     

Theoretical study of the optimal shape of the front profile of the lens in the eye of the scallop,Pecten

The optimal shape of the front profile of the thick lens in the eye of the scallop,Pecten is theoretically, geometric optically investigated as a function of the refractive index of the lens and the retina, as well as of the geometrical parameters of the eye. The shape of the theoretical front surfaces is compared with that of the real, experimentally determined front face of the lens. The degree of correction of the lens for spherical aberration of the reflecting spherical mirror in thePecten eye is examined. The optimal shape of the front profile of the lens depends strongly on a set of parameters, such that a certain fine tuning is required among them to assure a full correction for spherical aberration. The extreme variability of the eye parameters and the shape of the front face of the lens in the scallop is inconsistent with this fine tuning requirement. The degree of correction of thePecten lens for spherical aberration might not be as good as it could be, a possible biooptical reason for which is discussed.     

Evaluation of the role of the adaptive result in the theory of the functional systems

The fundamental of the theory of the functional systems, i.e., the concept of the useful adaptive result as a universal system-forming factor is considered. It is suggested that the adaptive result is not system-forming in behaviors actualized exclusively due to activity of systems developed earlier. It is argued that positive mutations may serve as the system-forming factor for hereditary determined behavioral forms. In all other cases of goal-directed behavior (except conditioning) the aim of performance as a model of the future result plays the decisive role. Only in conditioning the classical concept of the system-forming role of the adaptive result seems to be undeniable. The refined ideas about the mechanisms of formation of the functional systems may be useful in analysis of a number of animal and human functions (learning, emotional stress, neuroses, etc.).     

Contribution of internal layers of the retina to the genesis of the light peak in the electrooculogram in the chicken

We report that in the Chicken retina, Na aspartate which selectively blocks signal transmission between the photoreceptors and second order neurons also largely modifies the EOG. In treated eyes, the standing potential is reduced and the LP which is very transient in the Chicken eye is substituted for by a reactivity to light with much slower rise and delayed culmination time. The data are discussed in terms of interaction between pigment epithelium and neuroretina in the pharmacological determinism of the LP.     

Reversal of the effect of the allosteric ligands of dCMP-aminohydrolase and stabilization of the enzyme in the T form

The 5-mercury derivative of dCMP is a substrate of deoxycytidylate aminohydrolase in the presence of mercaptoethanol. With this substrate a reversal of the effect of the allosteric ligands of the enzyme is observed. dCTP, which is an allosteric activator for aminohydrolysis of dCMP, becomes an inhibitor for the mercury substrate, whilst dTTP, an allosteric inhibitor for dCMP, becomes an activator for the mercury substrate.This observation has been interpreted by assuming that dCMP-Hg-S-CH₂-CH₂-OH is a substrate of the T form of the enzyme. By reacting dCMP-aminohydrolase in the T form (in the presence of dTTP) with glutaraldehyde, an enzyme has been isolated that is no longer active with dCMP, while it is fully active with the mercurated analog. Gel electrophoresis demonstrated that glutaraldehyde does not produce intermolecular crosslinks, but fixes 95% of the enzyme in a stable hexameric form by intramolecular crosslinks. The data are explained by assuming that glutaraldehyde stabilizes the enzyme in the T conformation.     

Optical characteristics of the eye of the flounder

Summary The winter flounder,Pseudopleuronectes americanus, is mildly hyperopic. However, chromatic aberration exists in significant amounts and therefore the eye may be emmetropic (zero refractive error) in natural conditions when light is restricted to shorter wavelengths. Large accommodative lens motion was observed along the direction of the pupil axis. This direction is rare among the teleosts and is the result of the unusual split origin of the retractor lentis muscle. While the lens is spherical, as in other teleosts, the retina is not uniformly distant from the lens. Rather, a vertical asymmetry exists such that dorsal and ventral portions of the retina are further from the lens than the central retina. In view of the existing large accommodative ability, this distortion of the globe is not likely to have an optical function but is probably due to the shape of the cartilagenous scleral cup supporting the eye in its extraorbital location. Further, the lens is overcorrected for spherical aberration so that rays passing through the periphery of the lens are focused further away. The value of a lens of this type is unclear.     

Natural foci of diseases: the development of the concept at the close of the century

E. N. Pavlovski?'s concept of natural focality of diseases and the development of general knowledge about natural foci and their structural (components), functional (mechanisms of pathogen maintenance), and ecosystem-related organization (assortment and interrelations of ecosystems) are reviewed from principal (in authors' opinion) aspects. The 60-year history of this theory includes three stages at which its scope and contents differed. At the first stage, it concerned transmissible zoonoses. It had been assumed that structurally, natural foci necessarily include the pathogen-vector-host triad, and the functioning of the focus is provided for by only pathogen circulation in terrestrial ecosystems. At the second stage, it became clear that vector is not a necessary structural component of any focus (an example of nontransmissible diseases), although the functioning of foci remained to be unequivocally attributed to the continuous pathogen circulation among animals of terrestrial ecosystems. The third stage is characterized by an understanding that, in general, the presence of a warm-blooded host in the focus is also unnecessary for pathogen survival, and natural foci can be represented by soil and aquatic ecosystems. The only necessary and specific component of any natural focus is the pathogen population. In this context, modern views on natural focality of diseases are reviewed, and the essence of the terms "natural focus" and "epizootic process" is defined. It is proposed to distinguish the phases of pathogen reservation and epizootic spread (circulation) in ecosystems of any type. The current state of this concept provides evidence that, in general biological terms, studies on natural focality of diseases belong to one of the fields of symbiotology.     

Development of the mucosa and differentiation of the lymphocytes of the vermiform appendix of the human fetus

One hundred and twenty-two appendices have been obtained from 12-30-week-old human fetuses and studied histologically (90) and immune-morphologically (32). Lymphoid follicles in the organ appear on the 17th week. Character of the epithelial and the reticular tissue structure in the area of the cupola including the lymphoid follicle have been studied. T- and B-lymphocytes have been stated to be present in the appendix of a 17-week-old fetus. As the fetus is further developing, the number of lymphocytes in the appendix increases: the amount of T-lymphocytes is practically constant, and that of B-lymphocytes increases. Direction of the lymphocytes migration out of the follicle is demonstrated. The lymphoid formations of the appendix are necessary for certain local protective reactions and already in the fetus they begin to participate in the general system of the organism's immunogenesis.     

Ultrastructure of the follicular epithelium in the ovary of the domestic duck during the period of slow growth of the oocyte]

The work describes ultrastructural changes in the follicular epithelium and ooplasm in the period of the slow oocyte growth. The morphology of follicular cells (well-developed endoplasmic reticulum, numerous free ribosomes) is considered as evidence of their synaptic activity whereas the morphology of ooplasm indicates to its accumulative function. It is supposed that at this stage nutritive substances enter the oocyte through the intercellular spaces and their absorption is brought about by means of microvilli on the oocyte surface. A specific organelle of the avian egg -- so called transosome, is described. Their structure, transposition and possible function are discussed.