POST-RADIATION EFFECTS

From Big Medical Encyclopedia

POST-RADIATION EFFECTS — the manifestations of effects of radiation of biological objects registered at clinical and special trials ionizing radiation.

Character and P.'s expressiveness e. depend on a dose, power and a type of radiation (see. Doses of ionizing radiation , Ionizing radiation ). Reaction on radiation (see) has the features depending on biol, an object. In cells the delay of division, a mutation of genes or chromosomes are observed; P.'s result e. there can be a death of a cell. Changes of kinetics of cell populations are a basis of reactions to radiation of metaphytes of plants and animals. At P.'s plants e. are shown by disturbances of growth rate, terms of vegetation, productivity, mutational changes, etc. At animals and the person reaction considerably becomes complicated since the developed regulatory systems providing are surprised homeostasis (see).

Item e. subdivide on somatic and genetic. Somatic P. e. — manifestations of effects of radiation directly at the most irradiated organism, and genetic — at posterity.

Reactions biol, objects on radiation depend not only on the size of a dose, but also on time which passed from the moment of formation of the main part of a total exposure dose. Item e. it is possible to subdivide on primary, early, late and remote. Primary P. e. — the changes of molecules of cells, and also body tissues which are implemented during it is insignificant small time terms under the influence of action of ionizing radiation and the including processes of ionization, education of free radicals, emergence of chemical reactions as a result of bond breaking and intramolecular reorganizations. Damage of intracellular structures, irritation of nonspecific receptors, a delay of cellular division or death of cells is a consequence of it.

Disturbances in cells and fabrics of the irradiated organism cause a complex consistently developing patol, changes. Early P. e. depending on distribution of a dose in time, localization and a type of influence are shown acute or chronic radial illness (see), and at local influence of external radiation or selective deposition of radionuclides — beam damages (see) bodies and fabrics with acute, subacute or hron, a current.

Late P. e. arise at partial reduction of the broken structures and functions of an organism. In addition to fabric and organ defects, they are characterized by frustration of a trophicity, disturbances of normal vzaimoreguli-ruyushchy influences of bodies, kompen-satorno-adaptive reactions.

In the bodies and fabrics which are not possessing intensive cellular updating, the remote effects of radiation in the form of defined a wedge, a syndrome or change of function arise sometimes in 2 — 10 and more years after accumulation of the main share of a total dose. The characteristic remote effects consider development of a cataract, developing of leukoses, malignant tumors, endocrine disturbances, etc.

At impact of ionizing radiation changes in various systems of an organism — hemopoietic, lymphatic, cardiovascular, nervous, sexual, immune come to light, in went. - kish. path, etc.

Changes of blood and marrow are most expressed. It was noted already during the carrying out the early studies devoted to influence of ionizing radiation on an organism. At radiation in the doses causing an acute radial illness the early expressed changes of blood and marrow develop. They are characteristic also of effect of radionuclides with selective distribution in the hemopoietic bodies, napr, radium-226, phosphorus-32, etc. At intensive long radiation of all organism defeats of system of a hemopoiesis are observed, expressiveness to-rykh depends on a dose (see. Hemopoiesis, pathology ).

Normal death or disappearance of cellular elements is compensated by formation of new cells of marrow. Under the influence of radiation in the hemopoietic bodies between separate cellular pools there are disturbances of a normal dynamic equilibrium which lead to insufficient reparative regeneration and to a cytopenia. The period of the greatest expressiveness of a cytopenia follows for early the arising temporary termination of cell fission and death of the young people low-differentiated and the sharing cells of the hemopoietic fabric. At the same time changes of duration of process of maturing of cells, and also are expressed to time of life of the majority of mature cells and speed of their inflow to blood unsharply.

Devastation of marrow begins immediately after radiation, at recovery there is its regeneration. Morfol, composition of blood after radiation depends, in addition to intensity of devastation, on time of life of mature cells of various sprouts and speed of their elimination. E.g., small life expectancy of neutrophilic leukocytes and thrombocytes causes bystry decrease in their number in blood. At the same time the quantity of erythrocytes in blood decreases more slowly because duration of their life apprx. 120 days.

There is a certain communication between an ionizing radiation dose, a death toll of cells and the beginning of regeneration. It allows to use data of researches morfol, composition of blood as the main criterion for evaluation of weight of the general radiation injury.

At hron, general irradiation the period of intensive accumulation of the main share of total beam loading proceeds with dominance of destructive and necrobiotic processes preferential in the hemopoietic bodies. At the same time the picture of blood in the certain range of doses significantly does not change owing to high fiziol, opportunities of the hemopoietic fabric. Further cumulation of effects of damage or increase in radiation intensity leads to the progressing cytopenia. After the termination of radiation regenerative processes begin to prevail. Datum level of a hemopoiesis is in most cases recovered.

Changes of a hemopoiesis at internal radiation by radionuclides are defined by their nature, quantity and features of distribution in an organism (see. Incorporation of radioactive materials ).

Various functions limf, systems under the influence of impact of ionizing radiation are broken in unequal degree. The most radio sensitive is function of a lymphopoiesis.

Changes in limf, nodes, a spleen and a thymus come to light already at an exposure dose 25 — 50 is glad (0,25 — 0,5 Gr). Radiation in a dose 200 I am glad (2 Gr) leads to the progressing devastation of an adenoid tissue in terms of several days to 1 — 2 week though quite complete regeneration is found further. Radiation in doses 400 — 800 I am glad (4 — 8 Gr) causes heavy damages with slow recovery of a hemopoiesis. Radio sensitivity of separate fractions of lymphoid cells is not identical.

At the general single exposition in the doses causing a radial illness in blood within the first days the absolute and relative lymphopenia is observed. Depth and firmness of a lymphopenia depend on an exposure dose that is the valuable predictive test in definition of weight of defeat. The lymphopenia remains and even progresses in the eclipse period of a disease a little.

At radiation injury there is a number of essential changes in a condition of cardiovascular system. All researchers noted at once after radiation decrease in the ABP with the subsequent recovery to initial level. At a small exercise stress tachycardia and lability of pulse develops. With 10 — the 20th day at severe defeats tachycardia is observed and arrhythmia is more rare; The ABP decreases, especially minimum. On an ECG — lengthening of an interval Q — T, flattening and weakening of a wave S — T and disturbance of intra ventricular conductivity.

At victims the hemorrhagic syndrome develops. There are hemorrhages on head skin, persons, a thorax, a stomach, inner surfaces of extremities, are observed nasal, pulmonary, gastric, intestinal, women have uterine bleedings. Quite often hematencephalons or a myocardium are a cause of death.

Development of a hemorrhagic syndrome is caused by disturbance of process of a blood coagulation, thrombocytopenia, reduction of a prothrombin of blood, increase in permeability and durability of vascular walls.

At radiation in the doses causing a radial illness of heavy degree after influence sharp general weakness, headaches, dizzinesses develops. On 2 — the 5th day the state improves. During this period symptoms are noted unstable nevrol: nystagmus, asymmetry tendinous, decrease in belly reflexes. According to an electroencephalography there is a decrease in reaction to a light irritant.

In hard cases in the period of a heat of a disease the phenomena of an infectious and toxic delirium are possible (see. Delirious syndrome ), all-brain and Meningeal symptoms or phenomena meningism (see). Tendon, periosteal and cutaneous reflexes are usually lowered. Sometimes there are focal nevrol, symptoms — increase in a tone on pyramidal or extrapyramidal type, clonuses of foot, patol, the reflexes, oculomotor frustration which are a consequence of vascular disorders, hypostasis of substance and a cover of a brain, and sometimes and mikronek-robiotichesky processes and hemorrhages in various departments of c. N of the village of Nevrol, symptoms in the period of a heat of a disease in the presence inf. complications are not specific.

At a radial illness of average degree initial nevrol, symptoms are expressed more weakly and are shown in later terms. In the period of a heat of a disease there are insignificant frustration intracerebral haemo - and likvorodinamik though the unsharp focal symptoms caused by them are possible. In some cases at radiation in doses 250 — 300 I am glad (2,5 — 3 Gr) it is long increase tendinous and periosteal and decrease in cutaneous reflexes, their asymmetry, and also the easy disturbances of a statics testimonial of the expressed change of a myelin of conduction paths remains. On EEG come to light gradual deepening of brake process in a cerebral cortex, decrease in reaction to a light irritant. Increase in a chronaxia of all muscles is noted. During recovery these phenomena are gradually normalized.

At a radial illness of easy degree after disappearance of weak symptoms of priming reaction since 2 — the 3rd day after radiation the health of victims improves and only on the 5th week after radiation worsens a little. Tendon and periosteal jerks decrease unsharply, noted a moderate hypomyotonia and easy frustration of a statics. With 45 — the 50th day after radiation gradual recovery of all indicators is observed.

At hron, the radial illness caused by general irradiation in small doses, the main a wedge, syndromes of reaction of a nervous system are not specific to radiation. At the same time they are very characteristic both on the sequence of development of symptoms, and on their correlation with other symptoms of a disease.

In process of increase of total doses three consistently develop nevrol, a syndrome hron, a radial illness: a syndrome of disturbance of neurovisceral regulation, an asthenic syndrome and (seldom meeting in the conditions of general irradiation) a syndrome of organic lesion of c. N of page.

Direct injury of c. the N of page defines development patol, process only at a nervous (cerebral) form of the radial illness caused by general irradiation in doses St. 8000 is glad (80 Gr). At doses 2000 — 8000 the c is glad (20 — 80 Gr). the N of page is involved in patol, process generally for the second time as a result of development of heavy metabolic frustration and hemodynamic disturbances. In the range of doses up to 2000 I am glad (20 Gr) to function of c. N of page are broken preferential during the periods of a critical state of an organism (a heat of a disease, the terminal period).

During recovery disturbances of cortical dynamics are normalized. However easily there are failures towards dominance of both exciting, and brake processes. The disturbances of interaction between bark and a subcortex remaining in some cases lead to development of an astenovegetativny syndrome, and at deeper disturbance of functions of subcrustal educations — to development of a diencephalic syndrome (see. Hypothalamic syndrome ).

The most frequent the wedge, manifestations of early reaction from outside went. - kish. a path at an acute radial illness nausea and vomiting, expressiveness are to-rykh depends on an ionizing radiation dose. At doses St. 600 I am glad (6 Gr) in early terms the liquid chair can be observed. These phenomena are caused as direct action of ionizing radiation on intestines, so by its neuroregulatory frustration. In a phase seeming a wedge. wellbeing of the expressed manifestations from outside went. - kish. the path is not observed.

In a phase of a heat of a radial illness at the doses exceeding 600 — 1000 I am glad (6 — 10 Gr), changes in cells of crypts of a small intestine are possible that is shown by symptoms of enteritis: a frequent fetid liquid chair, pains in intestines, disturbances of digestion. Are especially bright a wedge, signs of defeat went. - kish. a path at an intestinal form of the radial illness developing at general irradiation in doses 1000 — 2000 I am glad (10 — 20 Gr). It is characterized early (with the short hidden phase) and the expressed syndrome of heavy beam enteritis. On the 2nd week swelling and morbidity of a stomach are noted a frequent liquid chair with impurity of blood. At distribution of ulcer and necrotic process on all layers of an intestinal wall the peritoneal phenomena and symptoms of dynamic develop impassability of intestines (see).

At peroral receipt of slaborastvorimy products of nuclear division as a result of contact r-radiation symptoms of damage of intestines dominate. At inhalation receipt of both slaborastvorimy, and insoluble products of nuclear division they in a significant amount leave from lungs as a result of operation of the mechanism of clarification with the subsequent swallowing and receipt in went. - kish. path. Thereof intestines are also exposed to intensive radiation.

The soaking-up radionuclides it is long are late in crypts of intestines and mesenteric limf, nodes that leads to formation of high local doses. The intestinal syndrome develops: beam enteritis, balance upset of liquids and electrolytes, intoxication and bacteremia, are broken secretory and zymoplastic functions of a stomach and intestines.

At the first stage endocrine shifts at an acute radial illness have a number of common features about a stress reaction (see. Stress ), edges it is shown generally by excitement gi - potalamo - pituitary nadpochechniko-howl systems with the corresponding reaction of an adenoid tissue and blood. The shifts in endocrine correlations which are poorly shown during the first period of a radial illness considerably progress later. The second period matching a heat of a radial illness is characterized by more expressed endocrine dysfunction which is a consequence of a functional overstrain, dystrophy and destruction of neurosecretory kernels of a front hypothalamus.

Phase changes in adrenal glands are noted: increase in free 17 oxycorticosteroids in a blood plasma in the first days after influence and in the period of heavy a wedge, displays of a disease. Similar data are obtained in experiments on animals.

The general external irradiation causes in the first days the increase in function of a thyroid gland and strengthening of a resorption of a colloid which is replaced then the long oppression of function of gland which is slowed down by accumulation of a colloid in it. The thyroid gland is the most struck body at hit in an organism of products of nuclear division, especially at children. In it about 30% of the radioiodine which came to an organism concentrate. Absorbed doses in iron are 2 — 3 orders higher, than in other bodies. As a result of intensive radiation of a thyroid gland already during the next period its hormonal activity decreases, and in the subsequent the parenchyma is replaced with coarse-fibered connecting fabric. At smaller doses increase in function of a thyroid gland with the subsequent its decrease is observed. Damage of a thyroid gland is caused by disturbance of functions of a hypophysis, and then involvement in patol, process of other closed glands.

Radiation of seed plants in doses 600 — 700 I am glad (6 — 7 Gr) leads to the termination of a spermatogenesis, and at doses St. 900 I am glad (9 Gr) there comes full sterility. Radiation of ovaries causes destruction of ova and follicles at preservation of cells of a yellow body and stroma. The first signs of damage of follicles arise at a dose 50 is glad (0,5 Gr), temporary sterility for 1 — 3 years comes at radiation of ovaries in a dose 250 — 350 is glad (2,5 — 3,5 Gr). Higher doses result in irreversible sterility.

As a result of radiation of pregnant women at explosions of atomic bombs in Japan in the subsequent various malformations at children were observed. Were most often noted nanocephalia (see), hydrocephaly (see) and heart diseases (see. Heart diseases inborn ). High sensitivity of an organism to radiation in the pre-natal period is caused by intensive processes of division and differentiation of cells which during this period are most vulnerable. Depending on time of a bookmark, formation and a differentiation of these or those fabrics, bodies or systems they are during a certain period radio sensitive in much bigger degree, than the same bodies or systems of an adult organism. Radiation before implantation and at the beginning of an organogenesis, as a rule, comes to an end with pre-natal death. At radiation in the period of an organogenesis death of the newborn is possible, but diverse uglinesses are more characteristic. Radiation of a fruit in certain doses causes a radial illness in the newborn.

The greatest radio sensitivity of an embryo of the person is noted in the first trimester of pregnancy, especially after implantation. A critical period for a nervous system of a fruit is 3 — the 5th month of pre-natal development. The threshold dose for approach of changes in a nervous system in these terms does not exceed several tens is glad. Doses of radiation 50 — 200 I am glad (0,5 — 2 Gr) cause clear changes in the structural and functional organization of a nervous system of a fruit and the child of early age.

Damage of system of immunity — one of real effects of action of ionizing radiation on an organism (see. Immunology radiation ). At the same time nonspecific defense reactions and factors of specific immunity suffer, allergic reactions change, develops autoallergy (see). A consequence of oppression immunol, reactivity is the endogenous and exogenous infection, edges can be one of the main reasons for death at an acute radial illness.

Changes in lens — one of characteristic effects of local action of ionizing radiation (see. Cataract, beam ). Radiation damages of skin on terms of development and the nature of changes are close a century to reaction to radiation of other sites of face skin of the person (see. Beam damages , Radioepidermitis ). The phenomena of conjunctivitis are noted at single local exposition in doses 700 — 800 is glad (7 — 8 Gr).

Changes in a cornea after radiation arise during the first hours and days after radiation. All cycle of defeat and recovery comes to an end during 3 — 6 weeks. At doses of radiation in several thousands I am glad permanent damages of certain sites of a cornea develop.

The earliest reactions at radiation of an eye are the changes of electric potential of a retina and threshold size of phosphene revealed already at a dose of radiation 1 is glad (10 Gr), and also changes of dark adaptation of a threshold of visual irritation. Structural injuries of a retina develop at doses of radiation more than 3000 — 5000 is glad (30 — 50 Gr).

Morfol, and functional changes of sound, flavoring, olfactory and vestibular analyzers are noted generally only after local radiation in high doses.

The changes happening in an organism under the influence of radiation cause shifts of a metabolism. Biochemical, processes in the organism subjected to radiation by ionizing radiation can be subdivided into two stages: biochemical, changes in result of primary action of ionizing radiation and biochemical, the changes happening in an organism during the formation of a radial illness and its remote effects. The most general and typical changes of a metabolism happen at the height of a radial illness (see. the Nitrogen metabolism, in the irradiated organism , the Lipometabolism, at radiation injury , Carbohydrate metabolism, in the irradiated organism ).

Experimental post-radiation effects

At animals are revealed certain specific differences in reaction of various systems, including a hemopoiesis, on actions of ionizing radiation. Defeats of the hemopoietic system in earlier terms are shown at mice and rats. Disturbances of a hemopoiesis at Guinea pigs, dogs, pigs, monkeys are characterized by slower development. In 1 hour after radiation in lethal and sublethal doses in limf, nodes, hl. obr. in the centers of follicles, signs of disintegration of small lymphocytes and lymphoblasts which extends further to all limf are found. node. Total quantity of lymphocytes in limf, a node is sharply reduced due to disintegration and washing away in a lymph and blood. In limf, nodes a lymphopoiesis it is long it is not recovered.

In a spleen after a possible initial short-term phase of increase in its sizes owing to an excess krovenapolneniye there comes sharp suppression of a lymphopoiesis. During the first hours and days after radiation note obvious signs of disintegration limf, elements and the progressing reduction of follicles. In the next days follicles are not distinguishable any more, the pulp of a spleen takes a homogeneous form, is poor in cellular elements. The spleen decreases in the volume and weight.

During recovery in a spleen and limf, nodes former structural ratios are recovered.

At rabbits and dogs in the period of a heat of a radial illness the expressed increase in permeability of capillaries is revealed. Owing to change under the influence of radiation of intercellular substance in a wall of a capillary there is an exit of proteins of a blood plasma in the intercapillary fabric environment. Also sharp disturbance of durability of capillaries comes to light. Essential changes of small vessels take place. After nek-ry swelling of vascular walls with the phenomena of their homogenization clear signs develop plasmorrhagias (see), the vascular wall becomes impregnated with plasma, is homogenized, and the endothelium is exfoliated.

In heart at dogs and rabbits the long plethora of vessels of a myocardium, resistant vasodilatation, hl is observed. obr. arterioles, precapillaries and capillaries. In muscle fibers there are dystrophic changes and hypostasis. There is a swelling and fusion of collagenic fibers, disintegration of argyrophil fibers, mucoid hypostasis of the main interstitial substance.

Already in early terms after radiation the processes of oxidation and phosphorylation interfaced normal are broken. The condition of the centers of a sympathetic innervation, a vasomotor center and adrenoreaktivny biochemical, systems in peripheral vessels and heart changes. Change of pressor effect of adrenaline up to its full perversion testifies to it. The slowed-down recovery of function of a myocardium, bystry exhaustion of compensatory mechanisms at the raised loads of heart is noted.

At hron, a radial illness of change of cardiovascular system at dogs are generally a consequence of regulatory disturbances. In early terms and at rather small total doses of radiation the shift of regulation has preferential adaptive character. Becomes later than clearer insufficiency of regulation and there are signs of microstructural changes. The last, however, are not heavy and do not affect the general hemodynamics and function of bodies with the changed blood circulation.

Internal radiation in the doses causing a radial illness or breaking function of a respiratory organs causes increase of pulse, its weak filling, weakening of a cardiac impulse, dullness of tones and decrease in the ABP in animals; on an ECG — change of the QRS complex, a negative tooth of T. V vessels comes to light exfoliating of an endothelium, swelling, a razvolokneniye and plasmatic treatment of walls.

Some features a wedge, кар^ oozes of a cerebral form of an acute radial illness are found in different types of animals. So, at monkeys in a few minutes after radiation in doses 4000 — 6000 I am glad (40 — 60 Gr) there comes short-term acute weakness, the immobilization lasting several minutes and only after nek-ry improvement there are typical symptoms of priming reaction (vomiting, etc.), the atactic movements, convulsive attacks, an opisthotonos. At smaller doses of radiation into the forefront changes of other systems of an organism, however act and in these cases a number of dysfunctions of c is noted. N of page. So, directly after radiation at rabbits are observed increase in excitability and reactivity of a cerebral cortex as result of weakening of internal inhibition, disturbance of steadiness of processes of excitement and braking. On EEG strengthening of biocurrents of a brain is noted. Then in the next few hours there is a decrease in functional activity of a cerebral cortex. Excitability of bark decreases and its reactivity falls, the central periferi-chesky relations in a nervous system are broken, excitability of interoretseptor and analyzers changes. In c. the N of page arrives an excessive afferent impulsation from the damaged fabrics. It is excessive for the highest departments of c. N of page. In a cerebral cortex leveling and paradoxical reactions with the subsequent long braking develop.

Considerable decrease in operability of nervous cells and falling of their reactivity promote development of ultraboundary braking. So, e.g., the dose of caffeine leading before radiation to strengthening of bioelectric activity after radiation causes a deep depression of electric activity in a cerebral cortex.

The condition of permanent ultraboundary braking can not only irradiate on all cerebral cortex, but at a certain stage of a course of a disease extends to subcrustal educations. Relationship between bark and a subcortex is broken, the regulating influence of bark on a subcortex is weakened.

The behavior of the irradiated animals changes, however behavioural reactions at radiation injury suffer less, than separate simpler reflex reactions (oppression of conditioned and instinctive reflexes). Behavioural reactions can change at local radiation of the head in high doses.

Changes of c. the N of page arising at smaller exposure doses it is preferential in the period of a heat of a disease, can be revealed at morfol, a research. The most essential damages are found in kernels intermediate, a mesencephalon and dorsal kernels of a myelencephalon. As well as in other bodies, in a brain the circulatory disturbance in the form of plasmorrhagias, perivascular hypostases and hemorrhages in substance and covers of a brain is noted.

Defeats went. - kish. a path at animals in connection with shorter cellular cycle develop in earlier terms. Radio sensitivity of a small intestine is especially big, in Krom there is devastation of fibers and crypts (the kinetics of cells is similar to system of renewal of cells of marrow, but has other quantitative characteristics). Changes of cell populations in intestines are connected with a phenomenon of vertical elimination (exfoliating in a gleam of intestines of the died cells of an intestinal epithelium). Devastation of crypts is observed at mice on 1 — the 2nd day, and cells of an epithelium of fibers — in 3 — 8 days after radiation. In this time there is generally a death of animals at the expressed phenomena went. - kish. syndrome. At smaller doses of radiation at survivors of a zooblast of an intestinal epithelium are intensively recovered.

After radiation also some changes of functions of a stomach are noted. Researches of secretion of a gastric juice at dogs after radiation in doses 150 — 900 I am glad (1,5 — 9 Gr) showed the periodic changes of gastric secretion which are characterized by increase or its reduction. The period of increase in secretion is, as a rule, short. The permanent oppression of secretion which is characterized by reduction of the total and free acid is most expressed. At high doses of radiation the digesting ability of a gastric juice decreases. Also changes of motive function of a stomach and intestines are noted, in particular delay of motive function of all went. - kish. path. During the first period after radiation there are spastic phenomena in intestines, its permeability for foreign proteins and microorganisms increases. Researches of the microorganisms allocated from blood and tissues of the irradiated animals showed that they are typical representatives of intestinal microflora.

At morfol, a research went. - kish. a path of the irradiated animals in the period of a heat of a disease the expressed plethora and swelling of a submucosa is noted, in a cut hemorrhages develop later. In hard cases of hemorrhage can be followed by intestinal bleeding. Microscopic examinations allow to find profound changes of a mucous membrane of intestines. Hemorrhages in the depth of a mucous membrane, and also in the thickness of fibers of a small intestine are observed; in the subsequent necrobiotic changes develop. Lack of cellular reaction on border of a necrosis, accumulation in zones of a necrosis of a large number of microorganisms is characteristic.

On morfol, to indicators the liver is considered radio resistant body. However in it there are certain functional changes affecting a metabolism. At the irradiated animals changes of activity of fermental systems of a liver — cholinesterase and a catalase, disturbance of glikogenoobrazuyushchy function of a liver, increase in cholesterol, nonprotein nitrogen, reduction of content of chlorides are noted. In the period of a heat of a radial illness frustration krovo-and lymphokineses, and also dege-nerativno-necrobiotic changes of a parenchyma and stroma of a liver come to light.

The liver is one of the main bodies of deposition of products of nuclear division; in it about 15% of the soaked-up radionuclides collect. Also the radionuclides passing through intestines, circulating in blood and which are brought out of an organism with bile are a source of radiation of a liver. Dystrophic and necrobiotic injuries of a liver to these cases have focal character with sufficient compensation of function. Along with the centers of defeat there are sites without visible damages that is connected with accumulation of radioactive materials in the cells englobing colloid particles.

In a hypophysis in the first days after general irradiation increase in functional activity is found. In the period of a heat of a disease signs of destruction of organoids in ferruterous cells of a hypophysis come to light. In early terms of radiation injury there is an increase in content of thyritropic hormone in a hypophysis. In late terms thyritropic activity decreases owing to damage of the mechanism of removal of hormone from gland.

Electronic microscopic examinations of a hypothalamus at rats at a dose of radiation 900 I am glad (9 Gr) showed that the initial phenomena of destruction of neurosecretory cells are noted by the end of the eclipse period of a radial illness. Histochemical in neurons falloff of activity of a succinatedehydrogenase is defined. In the period of a heat of a disease at microscopic examination considerable vacuolation of cytoplasm of neurons, a reduction of substance of Nissl, the phenomenon of a karyopyknosis and a karyolysis comes to light.

Gonads are one of the most radio sensitive fabrics and bodies. In seed plants radiation causes the termination of division and destruction of a spermatogenic epithelium. First of all spermatogones, then spermatids and spermatocytes are surprised; mature spermatozoa are quite radiation-resistant. Radio sensitivity of a spermatogenic epithelium has specific features. The effect of defeat depends on a direct radiation effect as showed experiments with shielding of seed plants. According to morfol, radiation resistance of cells of Sertoli and intersticial cells radiation does not exert the essential and inhibiting impact on secretion of sex hormones at experimental animals.



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I. F. Zhiltsov.

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