Growth of intramuscular nerves in man during prenatal ontogenesis

Myelinization of the neural cell processes begins on the third month. At 4-5 months mesaxons appear. Then, together with increasing diameter of the neural fibers, formation of new myelin transmitters is going on.     

Assembly of the glomerular filtration surface. Differentiation of anionic sites in glomerular capillaries of newborn rat kidney

Glomerular development was studied in the newborn rat kidney by electron microscopy and cytochemistry. Glomerular structure at different developmental stages was related to the permeability properties of its components and to the differentiation of anionic sites in the glomerular basement membrane (GBM) and on endothelial and epithelia cell surfaces. Cationic probes (cationized ferritin, ruthenium red, colloidal iron) were used to determine the time of appearance and distribution of anionic sites, and digestion with specific enzymes (neuraminidase, heparinase, chondroitinases, hyaluronidases) was used to determine their nature. Native (anionic) ferritin was used to investigate glomerular permeability. The main findings were: (a) The first endothelial fenestrae (which appear before the GBM is fully assembled) possess transient, negatively charged diaphragms that bind cationized ferritin and are impermeable to native ferritin. (b). Two types of glycosaminoglycan particles can be identified by staining with ruthenium red. Large (30-nm) granules are seen only in the cleft of the S-shaped body at the time of mesenchymal migration into the renal vesicle. They consist of hyaluronic acid and possibly also chondroitin sulfate. Smaller (10-15-nm) particles are seen in the earliest endothelial and epithelial basement membranes (S-shaped body stage), become concentrated in the laminae rarae after fusion of these two membranes to form the GBM, and contain heparan sulfate. They are assumed to be precursors of the heparan sulfate-rich granules present in the mature GBM. (c) Distinctive sialic acid-rich, and sialic acid-poor plasmalemmal domains have been delineated on both the epithelial and endothelial cell surfaces. (d) The appearance of sialoglycoproteins on the epithelial cell surface concides with the development of foot processes and filtration slits. (e) Initially the GBM is loosely organized and quite permeable to native ferritin ;it becomes increasinly impermeable to ferritin as the lamina densa becomes more compact. (f) The number of endothelial fenestrae and open epithelial slits increases as the GBM matures and becomes organized into an effective barrier to the passage of native ferritin.     

Tubular structures associated with the endothelial endoplasmic reticulum in glomerular capillaries of Rhesus monkey and nephritic man

Summary Round bodies, tubular profiles and crystalline images have been studied by electron microscopy in the endothelium of seven normal young Rhesus monkeys and in the renal glomerular endothelium of two nephritic human patients. The crystalline images are most frequently formed by aggregation of round bodies, 200–240 Å in diameter. In Rhesus monkeys a variety of crystalline images are seen. On the contrary, in nephritic patients round bodies and tubular profiles are rare and less organized. In the glomerular endothelium of two normal men they were not found.The results obtained suggest that the round bodies, the tubular profiles and the crystalline images result from sectioning of a system of undulating tubules associated with the smooth endoplasmic reticulum. In nephritic patients the formation of such a tubular system could represent a change taking place within the affected cells as a pathologic response to the disease.This work was supported by U.S. Public Health Service (N.H.I.), Grant AI-04527-03-04, and by the Consiglio Nazionale delle Ricerche (C.N.R.), Contributo 115/0815/0-1365. The Authors are greatly indebted to Miss Hermina Spiele for skilful technical assistance.     

Development of the definitive kidney in the cynomolgus monkey (Macaca fascicularis)

Abstract: Formation of the definitive kidney in Macaca fascicularis embryos was investigated using light and electron microscopy. Appearance of the definitive kidney at stage 14 was indicated by the ureteric bud invading the metanephrogenic blastema. Glomerular capillaries originate from the connective tissue that surrounds the developing renal vesicle. At 46–100 days gestational age the more developed glomeruli show thinning of the capillary endothelium, thickening of the basal membrane, and presence of pedicels, suggesting a capability of renal function.     

Structural organization of rabbit neocortex in prenatal ontogenesis

In the review on the basis of data of different authors, the development dynamics of the rabbit neocortex in prenatal life is presented. The main points of neurons development, interneuronal contacts, layer-by-layer and areal differentiation as well as neocortex afferental and efferental communications, that are elucidated ambiguously by investigators, are discussed. For the purpose of determination of the neocortex maturation to the birth-date the comparative analysis of the reference morphological data and author's own neurophysiological data is accomplished.     

Development of the seminiferious tubules and rete testis during the prenatal period of human ontogenesis

The sources of origin and the peculiarities of formation of the seminal ducts and rete testis during the prenatal period of ontogenesis in man were studied. It has been established that the seminal duct sand the ducts of the rete testis form from the cellular cords of the coelomic epithelium and the primordial germ cells which appear simultaneously in the septum of the testis and the primordial germ cells which appear simultaneously in the septum of the testis and central part of its parenchyma in the embryos, 13.0--17.0 mm long. By plastic and graphic reconstruction, as well as by methods of subtle preparation under binocular microscope MBC-I control it was revealed that the seminal ducts anastomosed between themselves both within the limits of one and the adjacent lobules. The ducts of the rete testis do not form anastomoses, but superimpose over one another, creating an impression of a rete. Approaching the tunica albuginea they merge, continuing into the cuctuli efferentes testis.     

Ultrastructural changes in the components of the filtration barrier in the glomerular capillaries of a remaining kidney following its temporary ischemia

The components of the filtration barrier of the glomerular capillaries of the rat remaining kidney were studied ultrastructurally 3, 7, 14, 30, 60, 180 and 360 days after exposure to 30 minutes and to 1-2 hours of ischemia. Submicroscopic changes found in the glomerular capillaries and in compensation -adaptive processes occurring in the remaining kidney were ascertained to be dependent on the duration of ischemia and the time elapsed since recirculation in the kidney. After 30-minute ischemia experienced by the remaining kidney the structural alterations in the glomerular capillaries were not remarkable, disappearing 14 days following recirculation, with the emergence by that time of the signs of hyperplasia and hypertrophy of intracellular structures. After raising the time of temporary ischemia of the remaining kidney up to 60 min followed by recirculation, appreciable ultrastructural postischemic disorders were recorded in the components of the filtration barrier of the glomerular capillaries. In addition, the compensation-adaptive processes in the kidney remained suppressed for a longer period of time. All these disorders were particularly demonstrable as a result of 2-hour ischemia. It was also discovered that destructive processes dominated over reparative ones thereby leading to the animals' death at early times of experiment.     

Antioxidant role of autophagy in maintaining the integrity of glomerular capillaries

Autophagy is a lysosomal degradation system by which cytosolic materials and damaged organelles are broken down into basic components. To explore the physiological role of autophagy in glomerular endothelial cells (GEnCs), we compared the autophagic flux among cells in the kidney under starvation. Inhibition of autophagy by chloroquine administration significantly increased the number of autophagosomes or autolysosomes in GEnCs and proximal tubular cells, but not in podocytes, suggesting that the GEnCs exhibit substantial autophagic activity. Next, we analyzed endothelial and hematopoietic cell-specific atg5-deficient mice (atg5-conditional KO [cKO] mice). Glomeruli of 4-wk-old atg5-cKO mice exhibited slightly distended capillary loops accompanied by an accumulation of reactive oxygen species (ROS). Glomeruli of 8-wk-old atg5-cKO mice showed a lobular pattern with thickening of the capillary loops and mesangial matrix expansion; however, the vasculature of other organs was preserved. The atg5-cKO mice died by 12 wk of age, presumably due to pancytopenia resulting from the defect in their hematopoietic lineages. Therefore, we subjected 4-wk atg5-cKO mice to irradiation followed by bone marrow transplantation from normal littermates. Transplanted mice recapitulated the glomerular phenotypes of the atg5-cKO mice with no obvious histological changes in other organs. Twelve-mo-old transplanted mice developed mesangiolysis and glomerulosclerosis with significant deterioration of kidney function. Administration of N-acetyl-l-cysteine, a ROS scavenger, to atg5-cKO mice rescued the glomerular phenotypes. These data suggest that endothelial autophagy protects glomeruli from oxidative stress and maintains the integrity of glomerular capillaries. Enhancing endothelial autophagy may provide a novel therapeutic approach to minimizing glomerular diseases.     

Rebuilding of rat intestinal mucous epithelium in prenatal ontogenesis

Morphological differentiation of the intestinal epithelium in the laboratory rat occurs between the 16th and 21st day of prenatal development. The pseudostratified epithelium is rebuilt into simple epithelium of the future lining. A characteristic sign of this rebuilding is formation of primitive folds, villi and intraepithelial vacuoles corresponding in submicroscopic picture with a secondary luminization. On the tips of folds and villi groups of cells released from the epithelium are observed. In these cells expression of activated caspase-3 confirms the presence of apoptosis in the process of cell death during epithelium rebuilding.     

Development of the paravascular bed of the vessels of the human heart during the prenatal period of ontogenesis

The paravascular bed of the cardiac vessels has been studied in 128 human fetuses at the age of 3-9 lunar months. Anatomical and histological techniques have been used, morphometrical analysis has been carried out. The paravascular bed of the cardiac wall vessels begins to form from the vascular epicardial network and from the paraneural vessels in 5-month-old fetuses. The paravasal longitudinal tracts are the first to form (the venous ones preceed the arterial). During the seventh month the nutritive vessels and the intramural networks of the main cardiac arteries and veins develop. The formation of the paraarterial bed is connected with the vascular diameter and with thickness of the arterial walls. Certain regularities in development of the venous paravascular bed are defined. By the beginning of the 8th month there are all main components of the paravascular bed of the cardiac vessels.     

Structure of the glomerular capillaries of the domestic chicken and desert quail

The glomerular capillary architecture of nephrons that include a loop of Henle (looped) and those that lack the loop (loopless) nephrons was examined qualitatively and quantitatively by electron microscopy in Gallus gallus and Callipepla gambelii. The glomerular capillaries of looped nephrons form a dichotomously branched network, while those of loopless nephrons are arranged loosely, and the majority are unbranched. There was no significant difference in the diameter of the glomerular capillaries between looped and loopless nephrons; however, in all cases the diameter of the afferent arteriole was significantly larger than that of the efferent arteriole. Based on size alone, the predicted blood flow rate in the efferent arteriole in 20% that of the afferent arteriole in G. gallus and 7% that of the afferent arteriole in C. gambelii. There was no significant difference in the volume density (Vv) of the glomerular capillaries between looped and loopless nephrons. However, the surface area density (Sv) of the glomerular capillaries in loopless nephrons of C. gambelii was significantly larger than for the looped nephrons, and for the loopless nephrons in G. gallus. This suggests that there may be a decrease in blood flow rate along the glomerular capillaries of the loopless nephrons in C. gambelii. Overall, the results indicate that the avian glomerular capillaries are less complex than those of mammals. Reasons may be that either avian blood is more viscous than that of mammals or that avian erythrocytes may be unable to fit physically through a tight intertwining network of capillaries due to the presence of a nucleus, which limits the tank-treading ability of avian erythrocytes. © 1995 Wiley-Liss, Inc.     

Functional maturation of the cat visual cortex during prenatal ontogenesis]

Development of the perceiving function of the visual cortex was studied on the foeti of cats in the second stage of antenatal development with intact placental blood circulation. It has been found that functional maturing of the cortical end of the visual analyser starts at the beginning of the second half of antenatal life. At this period EPs to stimulation of the optic nerve are recorded throughout the dorsal cortex of the contralateral hemisphere. At first they appear as slow three-phase (positive-negative-positive) oscillations of a small amplitude. As the foetus develops, the EP amplitude increases, and the EP configuration in the striate zone of the cortex becomes complex. Two weaks before birth, a short-latency negative wave appears against the background of the primary positive oscillation. In the last week of antenatal development of the foeti and in the first few days of the kittens life, EPs are represented in the specific zone of the visual cortex (g. lateralis) as two negative oscillations, and in the so-called associative zone (the middle part of the suprasylvian gyrus) by one long-latency high-amplitude negative oscillation which corresponds by latency to the second negative EP component in the striate cortex.