Electron microscopic study of the cytoskeleton of human podocytes

The ultrastructural study of man's cytoskeleton of podocytes is carried out. Populations of podocytes with two different types of structure of the cytoskeleton in dependence on age (2, 4, 6, 37 and 65 years) is revealed in kidneys. The first type of cytoskeleton of the podocyte is peculiar for children's age and is characterized by branched, high density microfilament network, expressed by system of microtubules and single myofilaments. The intermediate filaments here are either utterly absent or present so feebly they find themselves "disguised" by other strongly developed components of cytoskeleton and revealing them with the help of technique of electron microscope is impossible. In kidneys of adults, and especially of old aged persons podocytes with other type of organization of the cytoskeleton are mainly identified. The distinctive signs of the last are bundle arrangement of microfilaments, plural bundles of intermediate filaments and individual microtubules. This study permits to make a conclusion that during individual development and growing old in kidneys of high animals and man, probably, physiological changes causing morphological reconstruction of cytoskeleton which is accompanied by intensive development of intermediate filaments' system with simultaneous "involution" of microtubules and microfilaments' systems take place.     

Analysis of ring-shaped nucleoli in serially sectioned human lymphocytes

Summary Serial section analysis has demonstrated that ring-shaped nucleoli of mature human lymphocytes are spherical structures consisting of a peripheral ribonucleoprotein shell that surrounds one large fibrillar center. The shell exhibits usually one or, less frequently, two openings. The fibrillar center is in contact with the nucleoplasm and perinucleolar condensed chromatin, which frequently appears as a pedicle-like structure. Several chromocenters are associated with the ring-shaped nucleolus.     

Electron microscopic localization of hydrolytic enzymes in osteoclasts

Synopsis Acid glycerophosphatase activity (pH optimum, 5.0) has been found within osteoclasts by numerous workers but relatively few studies have been concerned with the neutral hydrolytic enzymes that have pH optima around 7.2. Evidence is presented in this paper to show that neutral enzyme activity can be demonstrated withp-nitrophenyl phosphate, ATP andp-chloranilidophosphonate as substrates. Activity against -glycerophosphate, inorganic trimetaphosphate orp-nitrocatachol sulphate as substrates was found to be limited to an acid pH range.Electron microscopic evidence indicated that many of the hydrolytic enzymes were present within single membrane-bound bodies, vacuoles, Golgi elements, and the agranular endoplasmic reticulum of the osteoclast. This reticulum was dilated to form large lysosomes. Such activity was distingly different from the function of the Golgi membrane in its formation of primary lysosomes.The relationships between lysosomes, cytoplasmic vacuoles, and extracellular release of enzyme through the specialized ruffled border are shown and discussed.     

Electron microscopic morphometric analysis of human T and B peripheral blood lymphocytes

Using the system of morphometric analysis described in this paper, human peripheral blood T and B lymphocytes, labeled with specific surface markers, can be compared on different analytical levels. They show differences in their surface and the eccentricity of cells, in the relative surfaces occupied by peripheral and central condensed chromatin, in the average surface of the central chromatin clumps and in the number of perichromatin granules per nuclear surface. The morphometric analysis reveals the importance of examining the nuclear and the surface parameters in the characterization of lymphocytes, confirming that a detailed analysis of the nuclear characteristics can contribute to the identification of T and B lymphocytes by transmission electron microscopy.     

Electron microscopic localization of cholinesterases in the rat myoneural junction

Summary The distribution of acetylcholinesterase (E.C. 3.1.1.7.) and other cholinesterases (E.C. 3.1.1.8.) in the fine structure of the myoneural junction of the rat diaphragma was studied, using acetylthiocholine and butyrylthiocholine as substrates. p]Acetylcholinesterase was located in the muscle sarcoplasm closely related to the postsynaptic membrane. Other cholinesterases are observed in the primary and secondary synaptic clefts and between the axon and the teloglial cells.     

Electron microscopic localization of monoamine oxidase in the rat liver

Summary Two methods have been employed to localize monoamine oxidase activity in the cells of rat liver, using either 2-(2′-benzothiazolyl)-5-stryl-3-(4′-phtalhydrazidyl) tetrazolium chloride (BSPT) or ferricyanide as electron acceptor. With both methods monoamine oxidase activity was found both in the inner and the outer mitochondral membrane, although the outer membrane appeared the most probable location. In addition the BSPT method but not the ferricyanide method, revealed monoamine oxidase activity in the endoplasmatic reticulum. The results obtained by the two methods have been compared and are discussed in view of available biochemical data on monoamine oxidase. Supported by research grants from the National Research Council of Canada (A 3651), The Swedish Medical Research Council (4145) and M. Bergwall's Foundation, Stockholm.     

Electron microscopic study of the localization of penicillin acylase in E. coli cells]

The paper describes the studies on definition of penicillinacylase localizations in the cells of E. coli with the help of ferritin labeled immune sera and electron microscopy. Both the intact cells and the cells treated with the substances affecting the cell wall intactness were used. The study showed relation between penicillinacylase and the surface structures of the cell, i.e. the cell wall and the periplasmic areas. It was found that penicillinacylase got into the environmental medium with the splitted cell fragments which corresponded to the general mechanism of excretion of large high molecular compounds by gramnegative organisms.     

A further contribution on nucleoli of human lymphocytes.

Cultured human lymphocytes were investigated by means of light as well as electron microscopic procedures to provide more information on the structural organization of their nucleoli. The transformation of ring shaped nucleoli to nucleoli with less or more distinct nucleolonemata in PHA stimulated cells was characterized by a marked increase of granular RNP components in number indicating the activation of their production. This phenomenon seems to be related not only to the activation of the ribosomal RNA synthesis but also to its processing. The appearance of fibrillar RNP components in the central area of the ring shaped nucleoli apparently represents the first sign of the nucleolar RNA synthesis in these cells. The proportion of fibrillar and granular nucleolar RNP comonents in PHA inresponsive lymphocytes was similar to that in lymphocytes from patients with the usual type of lymphocytic leukemia. The intranucleolar chromatin areas appeared to be larger in PHA stimulated lymphocytes but the proportion of these areas to the nucleolar body did not show substantial difference as compared to the resting cells.