Interference microscopy of human dental enamel at various age periods

Investigation of the human tooth enamel by means of interference contrast makes it possible to reveal certain peculiarities of the prismatic structure in various age groups. For example, in children the enamel has specific porosity of the superficial layers, that is peculiar for teeth with a delayed eruption. With age the enamel becomes more "homogeneous", amount and size of the pores decrease, aprismatic areas in the superficial layer are found more often. Erased teeth are characterized with formation of microdefects, destruction of prisms on the enamel surface and at the same time with increased mineralization of the subsuperficial layer. Thus, age changes of the enamel are of adaptive character--consolidation of structural elements promotes increasing resistivity of the teeth to influence of pathological factors.     

Developmental characteristics of the human lumbar spinal column at various periods of ontogeny

Regularities in development and differentiation of vertebrae have been investigated according to ageing. The data concerning the size of the vertebral canal at the level of the lumbar vertebral bodies and intervertebral discs, intensity of increase of these dimensions in various age periods, the character of spatial relations of sizes and form of the canal has been analysed. The transversal section area of the canal and the body in the corresponding segment varies between 1:3 and 1:5.5. By means of x-ray osteophotometry the mineralization degree of the lumbar vertebral bodies has been determined in men of various age. An important fact has been stated on a close connection between mineral saturation in juvenile and first mature ages with induces of general strength.     

Configuration of the cervical part of the spinal column in various age periods

In order to estimate pathological deformities of the spinal column, it is necessary to know its normal configuration during various age periods. For this 240 men and women in age groups from 15 up to 60 years and older, having not any complaints, have been investigated. Each patient is subjected to a standard x-ray examination of the cervical part of the spinal column in 2 projections with a subsequent roentgenography In the roentgenograms (lateral projection) angles between ventral bodies CII and CVII are measured, as well as angles in every segment. Indices of the cervical lordosis for every age group in men and women are estimated. The form of the cervical part of the spinal cord in men and women is not equal and changes in different age periods. During the middle age lordosis decreases both in men and women and again increases in the elderly age.     

Electron microscopic study of the epiphysis in the hen in different age periods

Electron microscopic investigation of the epiphysis in 1 and 2 years old hens revealed that pineocytes are rich in mitochondria, ribosomes, granular endoplasmic network, Golgi apparatus, synapses. In contrast to 1-year hens, large amounts of lipofuscin granules and lysosomes were found in older animals. The data obtained reveal intensive hormone formation and oxidation-reduction processes in the epiphysis of birds.     

The kinetics of the cell population of human liver parenchyma at different periods of life]

Processes of polyploidization in the liver parenchyma were investigated in the course of postnatal organism growth, stabilization of growth and ageing, using cytophotometry on the slides of isolated hepatocytes from normal livers of 140 donors aged from 1 day to 92 years. In addition, livers of human embryos (4, 5, 6 and 7 month old) were investigated. It is concluded that polyploid cells in the human liver appear in individuals aged from 1 to 5 years. However, during the postnatal development their relative number increases insignificantly. At the end of the intensive postnatal growth period the share of polyploid human liver cells is less than 3%. Binuclear cells with diploid nuclei are seen as early as in the embryonic liver. After birth their number increases slowly to reach 7.1% in the 16-20 year age group. The postnatal growth of human liver is due mainly to mitotic divisions of mononuclear diploid hepatocytes whose relative number is more than 90% during the postnatal growth. During the period of maturity (from 21 to 50 years), when the liver practically stops to grow, the levels of hepatocyte ploidy are changed insignificantly: part of 2c-hepatocytes decreases slowly (up to 84.8% by the end of period) and (2c x 2)-hepatocyte number increases slowly too. The number of polyploid cells increases by several times, but is equal only to 6.6% of all the hepatocytes counted. Under ageing, on the background of human liver atrophy, acceleration of hepatocyte polyploidization takes place. In the age group of 86-92 years parts of 2c- and (2c x 2)-hepatocytes reach 60.3 and 14.3%, resp., and the total share of polyploid cells is as much as near 25%, calculated from the cell population of liver parenchyma. The maximum ploidy levels in hepatocytes of normal human liver during ageing is becoming 16c and 8c x 2 for mononuclear and binuclear cells, resp. Transition rates among hepatocytes of different ploidy classes (2c--2c, 2c--2c x 2, 2c x 2--4c, 2c--4c) were calculated in addition to the coefficient of changing of the hepatocyte proliferative activity with the increase in its ploidy and cell death rate in different periods of human life. A rather high hepatocyte proliferative activity in the early postnatal period of human life was seen to lower during the following years of life. In maturity it is the lowermost to make less than 5% of that in newborns. During ageing the hepatocyte DNA-synthesizing activity being almost 1.6-1.7 times as much as in maturity.(ABSTRACT TRUNCATED AT 400 WORDS)     

Effect of nociceptive stimulation on the mitotic activity of cutaneous epithelial cells surrounding a wound at different age periods

Wounds, 1 cm in length, reaching the cutaneous muscle were inflicted to rats, aged 11 days, 2 and 2 1/2 months, under the right scapula. In 48 hours the animals were subjected to pain irritation with electric current. Mitotic activity was determined in the cells of the basal layer of cutaneous epithelium. Pain stimulation decreased the mitotic index of the cutaneous epithelium cells in animals of all the age groups under study considerably (several times). There was an increase of mitotic index from the early to later periods of postnatal ontogenesis.     

Functional morphology of the bronchovascular barrier of the human lungs during various age periods

Cellular components of the bronchovascular barrier have been studied in human lungs obtained after death of some patients with acute and chronic lung inflammatory diseases, hypertonic disease, atherosclerosis and chronic glomerulonephritis. Certain oxidative-reductive and hydrolytic enzymes, including NAD-, NADP- diaphorases, lactic dehydrogenase, acid and alkaline monophosphoesterase, ATP-ase, adenylate cyclase and nonspecific esterase were evaluated quantitatively after the histochemical processing of the specimens for the above reactions. Correlation analysis was performed for the bronchial epithelium, endotheliocytes, lymphocytes, plasma and mast cells, as well as macrophages and polymorphonuclear leucocytes. The results showed that there was a significant shift in some of the measured enzymic activities. Moreover, the correlations between different quantitative data were noted and these correlations changed with age. The increase in "rigidity" of the correlations in the elements of the bronchovascular barrier has been demonstrated during the process of ageing.     

Peculiarities of human lung prenatal morphogenesis at the first trimester of pregnancy in different periods after Chernobyl accident

The comparative histological and morphometric analysis of the bronchial structures of human fetal lungs was performed. Fetal lungs were taken from pregnant women living in radionuclide polluted zones (Novozibcov, Bryansk region) or in control regions (Moscow) in different periods after Chernobyl accident. Relative areas of the bronchial epithelial tubes and mesenchyme, quantity of bronchial branches and buds (end sections) of epithelial tubes on cut area unit were determined. The dates received in 1992-1993 showed the delay of fetal bronchial growth and branching in comparison with control. It can be estimated as tissue dysplasia of lungs from fetuses of mothers living in Novozibcov. The material received in 1995 showed the more intensive growth of bronchial branches in human fetal lungs than the material from Novozibcov and of the Moscow control, taken in 1992-1993. These date suggest the heterogenous character of lung prenatal morphogenesis reactions of offspring from pregnant women lived in different periods on controllable territories of Bryansk region.     

三种白及属植物不同生长发育时期的菌根显微结构

采用石蜡切片技术对白及Bletilla striata、黄花白及B. ochracea和小白及B. formosana的栽培种在生长期、花期、果期和休眠期的菌根解剖结构特征、菌根真菌入侵方式和菌丝特征等进行观察研究,以进一步了解菌根真菌与白及属植物的共生关系。结果表明,3种白及属植物的菌根真菌均是通过通道细胞侵入根皮层薄壁细胞,侵入后菌丝靠近皮层细胞的细胞核分布,最终在皮层细胞形成菌丝团;真菌侵染率和菌丝形态随着植物生长发育变化而变化,3种白及属植物均表现为花期和生长期的真菌侵染率较高,以丝状菌丝团为主,而果期和休眠期较低,以团块状菌丝团居多;同一时期不同植物类型的菌根特征无显著差异。     

禁食不同时段下丘脑穹窿周区orexin-A的表达

目的探讨禁食不同时段大鼠下丘脑穹窿周区orexin—A的表达及是否与摄食有关。方法观察禁食前后大鼠体重变化,采用免疫组织化学染色法观察禁食不同时段下丘脑穹窿周区orexin-A的表达变化,灰度值测量观察各组orexin—A的染色强度。结果大鼠体重随禁食时间的延长而逐渐降低,各组大鼠禁食前后体重变化有统计学差异（P〈O．01）;Orexin-A主要分布于下丘脑穹窿周区,禁食组orexin—A阳性神经元计数明显多于对照组（P〈O．05）,但不同禁食组间orexin-A阳性神经元计数比较没有统计学差异（P〉O．05）;禁食48h组染色强度最深,与对照组和禁食24h、72h组有明显统计学差异（P〈0．05）。结论禁食可以促进orexin-A的表达,禁食48h应该是一种理想的促进orexin-A活化的刺激方式,orexin-A系统可能参与摄食及能量代谢的调节。