Mitotic activity of pial microvascular endothelium rat in postnatal ontogenesis

Mitotic activity of endothelium in pial microvessels has been studied with the aid of intra-vessel autoradiography in 4-, 12- and 30-day old rats using these parameters: number of labeled nuclei per vessel or per 100 mcm of its length, or per 1 mm2 endothelial surface area, as well as number of vessels with labeled endothelium cells. The first parameter was independent of vessel diameter. The other parameters had highest value in the pericapillary vessels in all rats. These values decrease with rat age. The highest rate of brain growth was revealed after reaching the greatest mitotic endothelium activity in pial bed.     

Rhythmical electrical activity in the cat stellate ganglion during postnatal ontogenesis

Electrical activity of the stellate ganglion was studied in newborn, 10-, 20-, 30-day-old, two- and six-month-old kittens using the spectral analysis. The development of sympathetic activity patterns was different during ontogenesis. The amplitude of discharges increased from the period of birth until the second month of kittens' life. In newborn and 10-day-old kittens, synchronous discharges of postganglionic fibers were represented by slow and low frequency impulses with frequencies of breathing and heart rate. ppears in 20-day-old kittens. The formation of the sympathetic discharge patterns ends at the second month of animals life.     

Lectin receptors in the salivary glands of the rat during postnatal ontogenesis

Distribution of lectin-binding sites in rat submandibular and sublingual salivary glands during postnatal development has been investigated. Lectin preparations include con A, lentin lectin, castor beans agglutinin, peanut, soybean and Sophora japonica agglutinins, wheat germ agglutinin and lectin from the bark of Laburnum anagyroides. The direct and indirect peroxidase techniques are used. According to the similarities of histochemical patterns, all lectins are divided into four groups. Besides the general patterns of lectin binding sites, some details are noted. Lectins of peanut and Sophora japonica possess an extremely high affinity to mast cells, con A, lens lectin, castor beans and wheat germ agglutinins--to serous demilunes cells. Laburnum lectin--to salivary ducts epithelia in adult rat salivary glands. Lentin lectin, con A and Laburnum lectin preferentially stain cells with specific granularity in granular ducts at early stages of postnatal development. Considering the character of staining, we propose for further histochemical investigations of the salivary glands lentin lectin, peanut agglutinin, wheat germ agglutinin and Laburum anagyroides lectin.     

Proliferative activity of cells of the intermediate lobe of the rat pituitary during the postnatal period.

Cellular proliferation was studied in the intermediate lobe (IL) of the pituitary gland of developing rats by labelling cells at the S-phase of the cell cycle with bromodeoxyuridine (BrdU). The number of BrdU-labelled cells in the IL decreased from birth until the 14th postnatal day and was low from that day until the end of the first month after birth. Throughout the postnatal period a large proportion of BrdU-labelled cells was found in the marginal layer (ML) of the IL, suggesting for the ML a role as a germinative layer of the IL during postnatal growth. Double immunostaining with anti-BrdU and anti-MSH showed that MSH cells actively proliferate as from the day of birth. Cells doubly immunostained with anti-BrdU and anti-S100 protein were first seen on the 14th postnatal day. From then onwards, most proliferating cells were labelled with either anti MSH or anti S-100 protein. This, together with the high proportion of proliferating cells found in the ML marks a clear difference with the pattern of cellular proliferation previously reported during a similar period in the anterior lobe of the rat pituitary.     

The glomerular apparatus and renal blood flow in rats during postnatal ontogenesis

In anesthetized Wistar rats of the age of 4, 12, 30 and 65 days, the renal blood flow (RBF) with laser-Doppler flowmetry, diameter, number and density of glomeruli, diameter of afferent and efferent arterioles were measured. We found that during rat development the RBF increased 2.8-fold, the diameter of glomeruli--3.6-fold, diameter of afferent arterioles--1.8-fold, and the efferent arterioles--rose 1.3-fold. The number of glomeruli increased 1.3-fold, but their density decreased 16-fold.     

Mitotic activity of the endothelium of different-diameter blood microvessels in the mesentery of Wistar rats

The technique of intravascular autoradiography of 3H-thymidine labeled nuclei of microvessels endothelia was developed. The density difference of labeled cells in microvascular bed of mesentery was estimated. The maximal density of labelled nuclei was found in pre- and postcapillary vessels, and minimal--in capillaries and large arteries and veins of mesenteric bed. The number of labeled nuclei per vessel was found to be relatively constant. The density of labeled cells in 4-months old rats is less than that in 3 weeks-old ones.     

Quantitative changes of the C-cell population in the rat thyroid during postnatal ontogenesis

Summary The number and distribution of C-cells in the rat thyroid gland, have been investigated during postnatal ontogenesis from birth to 120 days of age. The argyrophilic and metachromatic properties of these cells were used to identify them. In the thyroid of newborn rats the C-cells do not exhibit argyrophilia and metachromasia. These reactions appear at 10 days and can be seen at all subsequent ages. The number of C-cells shows a parallel increase with age as demonstrated by the change in the proportion of C-cellsF-cellscolloidstroma during development. A marked increase in C-cells was found at 50 days of age when the proportion of C-cells rose to 27.67% from the value of 16.78% at 30 days. At 70 days a decrease was noted (20.50%) which hardly changed until 120 days of age (22.20%). The numerical increase in C-cells occurs at the expense of the follicular epithelium and stroma.The C-cells occupy elongated islet-like region in the central part of the lobe, decreasing in number towards the periphery where no C-cells are present. The long axis of the C-cells area is parallel with the longitudinal axis of the lobe. The area of C-cells is largest at the centre of the lobe, corresponding to the territory of the peak of the Gaussian curve for the numerical distribution of C-cells.     

Age and sex characteristics of phospholipid composition of Wistar rat erythrocytes during postnatal ontogenesis

The composition of phospholipids and fatty acids of erythrocyte lipids of intact mature Wistar rats and their progeny in the age of 10, 15, 20, 30, 40, 60, 90 and 110 days was studied with the methods of micro-thin-layer and gas-liquid chromatography. Sex features and age mechanism of erythrocyte lipids composition forming in physiologically standard conditions were established. The fact that the composition of erythrocyte lipids of the untreated grown-up male rats in comparison with the female species is characterised with a lower concentration of phosphatidylinositol, a higher level of phosphatidylcholine and sphingomyelin, a higher saturation level of molecular types of phospholipids, was described. Three age periods of homeostasis of the erythrocyte lipids of the intact rats were distinguished. The postembryonic period (30-40 days after birth) is characterised with forming of the basic pool of erythrocyte lipids: getting to the stability in levels of the basic components of phospholipids and their fatty acids, coming out of phosphatidylinositol by the 40th day after birth. The period of sex-growing (60 days) is accompanied by spasmodic changes in the levels of fatty acids which is most common for female species: rapid increase in saturated and omega 3 polyunsaturated fatty acids, decrease in monoene and omega 6 polyene fatty acids. The period of maturity (110 days) is characterised by a slow metabolism of structural lipids and a stabilisation of their composition.     

Various characteristics of the activity of skeletal muscles in humans and dogs during postnatal ontogenesis

At normal ambient temperatures, in absence of stress, in babies during first months of life (in contrast to less maturely born mammals), the respiratory activity of skeletal muscles is not realized, being observed only under stress conditions. In 1-1 1/2 months old puppies, after deafferentation of the hindlimb, the frequency of movements of a jerk type increases approximating the level observed in newborn animals. At normal ambient temperatures, these puppies exhibit respiratory activity of skeletal muscles which is not observed at this age in control animals.     

Change of composition of intermediate filaments in rat telencephalon during early postnatal period of ontogenesis

The goal of the present work was to study composition and spatial-temporal distribution of cells containing various proteins of intermediate filaments (nestin, vimentin, GFAP) in various brain areas at the early postnatal period of rat ontogenesis. By using methods of immunohistochemical determination of proteins of intermediate filaments, it has been found that at the early postnatal period of development, in the course of maturation of the nervous tissue, in the cells of cortex, hippocampus, and subventricular area, there occurred changes of immunohistochemical profile of intermediate filaments (ratio of immunopositive (+) and immunonegative (?) cells): nestin⁺/vimentin⁺/GFAP^? cells become nestin^?/vimentin^?/GFAP⁺.     

Dynamics of organ blood flow in rats in postnatal ontogenesis

In the 4-, 13-, 30-, and 65–90-day old anestetized Wistar rats (8–15 rats in each group) the voluminous blood flow rate was measured in liver, kidney, small intestine wall, and in the predominantly white gracilis muscle of femur. A LAKK-01 laser-Doppler flowmeter and its cutaneous (for kidney) and needle (for other organs) probes were used; they provided estimation of blood flow to the tissue depth of about 1 mm. It has been found that the blood flow rates (per organ mass unit) fall in liver, intestine, and even more in muscle, whereas increase in kidney, particularly for the first month of life. Calculations show that in adult rats as compared with the 4-day old pups (with their mass exceeding 22 times) the blood flow to muscle, liver, intestine, and kidney should rise (with taking into account the increase of mass of the organs) 14, 17, 18, and 43 times, respectively.     

Functional activity of leucocytes in postnatal ontogenesis of dogs]

Studies have been made on motile and phagocytic activity, osmotic fragility of neutrophilic leucocytes, as well as on their glycogen content in dogs of various age groups. Within the first 3 months of postnatal life of animals (especially during the 1st month), functional activity of leucocytes is lower than in adult dogs. With respect to functional activity of leucocytes, 6-month puppies stand closer to adult dogs, although exhibit some differences from the latter.     

Quantitative relationship of renal blood flow with size and density of glomeruli in rat postnatal ontogenesis

The aim of the study was to find the quantitative relationship of postnatal changes in the glomeruli anatomic structure with the blood flow in kidneys. Kidney development was studied in 4-, 12-, 30-, and 65-day-old Wistar rats. Diameters of glomerulus (Dgl, microm), afferent and efferent arterioles (Daf and Def), and the glomeruli density (Ngl, mm(-3)) were measured posthumously. Volumes of one ((see text of symbol))V gl, microm3) and all glomeruli (see text for symbol)(sigma(see text for symbol)Vgl, mm3/cm3) and the glomeruli arterioles lumen (Saf and Sef, microm2) were calculated. The renal specific blood flow (SBF per unit of kidney weight, KW) was measured by the laser-Doppler flowmeter (in perfusion units, p.u.) under sodium barbamyl narcosis. We have found that, during postnatal growth, glomeruli morphological parameters vary according to the equations: Dgl = 7.1 (see text for symbol) KW0.41, (see text for symbol)V gl = 187 (see text for symbol) KW1.23, Ngl = 5309 (see text for symbol) KW-0.63 (KW, mg and for one kidney), Saf = 1.1 (see text for symbol)V gl 0.35, and Sef = 6.3 (see text for symbol) V gl 0.14. The renal SBF in 4-, 12-, and 65-day-old rats increases according to SBF = 6.7 (see text for symbol) (sigma( see text for symbol)V gl)0.98. The renal SBF calculated per unit of glomeruli volume varies a little with age.