Intracytoplasmic Filaments Research Articles

ULTRASTRUCTURAL STUDIES OF THE MENINX

The menlnx of mature rabbits is constituted of dural, meningothelial and arachnoid layers. The meningothelial layer is composed of meningothelial basal cells and overlying subdural cells with curiously lobulated nuclei. Subdural cells contain numerous intracytoplasmic filaments and desmosome‐like structure, which are lacking in fibrocytes located just beneath the dura. The arachnoid layer shows a framework of the arachnoid cells, collagen bundles and vessels, and cisternae as a channel of cerebro‐spinal fluid are enclosed by the lacunar cell cords. The pia‐glial membrane separating the brain substance from the arachnoid is often complexly swirled together with the processes of marginal astrocytes.Subdural injection of Candida krussei produces suppurative and granulomatous foci, and the Intercellular spaces tend to be dilated by a retention of oedema fluid, blood or exudate. Intraarachnoid injection of the organisms also produces acute and chronic inflammatory changes, and the dissociation of lacunar cell cords at the desmosome‐like attachment may result in a widening and dilatation of the spaces. The meningothelial lining and pia‐glial membrane are considered to be a sort of barrier to protect the underlying tissue from various pathological changes.

Elektronenmikroskopische Untersuchungen an soliden Mammacarcinomen der H�ndin

The electronmicroscopic findings of nine solid mammary carcinomas in bitches are described as well as the observations on tumour cells within lymphatic vessels. In the primary tumours basement membranes surround the cords of tumour cell. In five cases, particularly in two, there are cells with long intracytoplasmic filaments measuring about 65 A thick. The filaments are arranged along the axis of the cells and show focal densities. These cells are presumed to be myoepithelial tumour cells. In eight of the nine tumours there are also carcinoma cells with short single or bundled intracytoplasmic filaments of approximately the same thickness (65 A). These however show no specific order, they are perinuclear or lie in between the organelles. They are called tonofibrillae. Viruses or virus-like particles have not been found.

Skin Vascular Ultrastructure During Thermal Injury, Hypertrophic Scarring and its Resolution

The usual result of deep thermal injury of the skin in children is hypertrophic scarring. The dynamics of revascularization have been implicated as integral to development and resolution of hypertrophic scarring. Thus, special attention is being directed toward examining vessels at different stages after injury.In vessels from normal skin endothelial cells do not contain many organelles; Golgi membranes are sometimes observed, a few mitochondria and occasional profiles of rough endoplasmic reticulum. Pinocytic vesicles are present on both tissue and blood side of the endothelial cells and in the perivascular satellite cells. Infrequently multivesicular bodies are observed. A thin basement membrane underlies endothelial cells and their satellites (Fig. 1).In the post-injury granulation tissue pinocytic vesicles and multivesicular bodies are seldom seen. The endothelial cells contain a marked increase in rough endoplasmic reticulum, often dilated, and intracytoplasmic filaments (Fig. 2).

Ultrastructure of a vaginal myxoma of a rat.

Ultrastructural study of a vaginal myxoma of an adult Wistar rat showed that the stroma consisted mainly of finely granular material with some fibers. The tumor cells contained numerous mitochondria, Golgi complexes, and associated vesicles, and moderate to abundant endoplasmic reticulum. Intracytoplasmic filaments and virus-like particles of about 120 nm were seen.

Specific organization of intracytoplasmic filaments in the dog testicular interstitial cell.

In the dog testicular interstitial cells the cytoplasmic filaments are occasionally arranged in large bundles piled closely in an extensive area adjacent to the Golgi region in the cytoplasm. Some of the large bundles show conspicuous circular or spiral configurations which are composed of elaborate arrangements of both circular and longitudinal filaments and accompany tubules of agranular endoplasmic reticulum running parallel to the longitudinal filaments.

Primary brain and spinal cord tumors induced by human adenovirus type 12 in hamsters.

Twenty-nine (37%) of 78 newborn hamsters developed an autochthonous malignant tumor of the central nervous system within 31 to 204 days after a single intracerebral inoculation of 0.01 ml of virus fluid, containing 103.5-104.5 TCID50 HeLa cells/0.1 ml. Eight solid tumors protruding into the ventricular system developed in the left cervical hemisphere where the virus was inoculated. In one case, entirely separate tumors were found in both hemispheres. Four were small incipient neoplasms located immediately adjacent to the ventricular system. Two appeared to block entirely the IVth ventricle. Three were situated in the medulla oblongata. Sixteen spinal cord tumors were found, mainly in the dorsal half of the column, without extension to the leptomeninges. Histopathological studies of all of these tumors showed a remarkable uniformity. The tumors were designated as the counterpart of human embryonic gliomas derived from the ependymal analge. Electron microscopy clearly revealed a single cilium with a typical concentric pattern of nine pairs of peripheral doublets with no central pair (9 + 0) in the apical processes of many tumor cells. The presence of cilia of neuronal origin suggests that these tumor cells mimic certain developing neurons (chiefly sensory). The presence of numerous intracytoplasmic filaments and microtubules in dysplastic neuronic cells also suggested a neuronal origin. Detection of immunofluorescent T-antigen in frozen sections confirmed the viral origin of the tumor. Subcutaneous transplantation of the tumor gave rise to rapid neoplastic growth in recently weaned hamsters. Control animals inoculated with the culture media developed no tumors.

Ultrastructure of a composite glioma-sarcoma of the brain.

The ultrastructural features of a composite glioma-sarcoma of the brain are described. Glial cells had short cytoplasmic processes, a highly developed rough endoplasmic reticulum and bundles of intracytoplasmic filaments 80–90 A thick. The nucleus contained evenly distributed chromatin and spheroidal bodies up to 5000 A in diameter. Mesenchymal cells had elongated cytoplasm, a rough endoplasmic reticulum with short cisternae, numerous lysosomes and groups of vesicles associated with the plasma membrane. Nuclei were elongated and contained spheroidal bodies similar to those observed in glial cells. The interstitial space contained abundant collagen fibers. The endothelial cells exhibited rows of pinocytotic vesicles and a well developed Golgi complex. The ultrastructural observations are considered confirmatory of the composite nature of these tumors. It is believed that the sarcomatous component originates in the hyperplastic endothelial cells.

The merkel cell in human epidermis: its differentiation from other dendritic cells

Until recently, Merkel cells were not consistently identified as the third dendritic cell in human epidermis, because light microscopy and low power electron microscopy did not readily allow the differentiation of Merkel cells from the other two dendritic cells of the epidermis (e.g. the melanocyte and the Langerhans cell). In an electron microscopic study where special attention was given to dendritic cells in human epidermis by higher power magnification, Merkel cells were characterized by the specific Merkel cell granules and fine intracytoplasmic filaments inserted into an occasional Merkel cell desmosome. Use of these criteria permitted definite differentiation of Merkel cell from melanocytes and Langerhans cells, as the latter have neither the typical Merkel cell granules nor fine filaments and desmosomes. The proximity of an epidermal neurite above the basal lamina or of a dermal neurite close to the basal lamina, further aided the detection and differentiation of Merkel cells in human epidermis. Preliminary evidence suggests that Merkel cell granules may contain catecholamines. Thus, the easy identification of Merkel cells by high power electron microscopy raises interesting questions for the role of this cell and its apparent catecholamine content in pathological states of the skin.

Colorado tick fever virus: an electron microscopic study.

Colorado tick fever (CTF) virus was observed by ultrathin section and negative contrast electron microscopy. In sections of infected cultured cells and of mouse brain, virus particles (75 mμ in diameter) with electron dense cores were associated with intracytoplasmic granular matrices, arrays of intracytoplasmic filaments, and fine kinky threads. Occasionally, virus particles were enveloped by membranes of cytoplasmic organelles. Intranuclear filaments in dense arrays were frequently found in infected cells. In negative contrast preparations the virus was round, 80 mμ in diameter, with regularly spaced surface projections suggestive of cubic symmetry. Partial removal of surface components permitted the observation of an inner capsid 50 mμ in diameter. CTF virus was directly compared with reoviruses, which in several ultrastructural characteristics it resembles.

Intracytoplasmic filaments in the cells of adult human articular cartilage.

Intracytoplasmic filaments in the cells of adult human articular cartilage.

THE POSTNATAL DEVELOPMENT AND DIFFERENTIATION OF THE BOUNDARY TISSUE OF THE SEMINIFEROUS TUBULE OF THE RAT.

AbstractThe morphology of the boundary tissue of the seminiferous tubule of the rat has been investigated in testes from animals aged from birth to four months. In the adult, the boundary tissue consists of four layers: (1) an inner non‐cellular layer comprising a network of collagen fibrils sandwiched between two basement membranes (2) an inner cellular layer of flattened cells showing many of the characteristics of smooth muscle, including intracytoplasmic filaments and micropinocytotic vesicles, (3) an outer non‐cellular layer containing scattered colagen fibrils and associated usually with a single basement membrane and (4) an outer cellular layer, component cells of which contain no fine filaments. At birth, the seminiferous tubule rests upon a basement membrane which separates it from a layer of low cuboidal cells. External to this, there is a narrow intercellular zone containing scattered fibrillar material and a region consisting of numerous processes of mesenchyme cells. By ten days postnatal, four definite layers are established due to the differentiation of an outer cellular layer of flattened cells from the mesenchyme, and intracytoplasmic filaments have made their appearance within the inner cellular layer. In subsequent stages there is progressive thinning and specialization of the cellular layers and increased fibril content within the non‐cellular layers. By 22 days postnatal the boundary tissue appears virtually adult in morphology.

Ganglion Cells in the Human Retina

Typically, a neuron has one or more dendrites, a single axon, a cell body (perikaryon), and a nucleus. By electron microscopy¹the cytoplasmic components of a neuronal cell body have been characterized by the presence of aggregates of short segments of granular endoplasmic reticulum (Nissl substance^1,2) surrounded by clusters of similar but unattached granules, the ribonucleoprotein particles (RNP), ("Palade granules," or ribosomes), the presence of an unusually large Golgi apparatus, intracytoplasmic filaments, and, usually, a number of electrondense granules.^1,3-6 The neuronal perikarya present in the innermost layer of retinal cells are similar in appearance to the large neuronal perikarya found in various ganglia and have therefore become known as "ganglion cells." These ganglion cells make up, for the most part, a single layer of neuronal cell bodies lying between the nerve fiber layer (their axons) and the inner plexiform layer (in part, their dendrites). In the macula,

Elektronenmikroskopische Beobachtungen an den Hülsenarteriolen in der Milz des Hundes

The endothelial cells of sheathed arterioles of dog spleen were found to contain an abundance of intracytoplasmic filaments about 80 A in diameter. The endothelium is surrounded by a fenestrated clastin skeleton. The sheath cells show signs of phagocytosis. A possible vasomotor function of the endothelial cells is discussed.

The formation of connective and skeletal tissues.

By the use of the electron microscope and thin sections of connective and skeletal tissues of the fowl embryo, observations have been made on the fine structural detail and the interrelationship between the cells and the developing collagen fibres and ground substance. Submicroscopical filaments have been recorded in the cytoplasm of four types of fibrogenic cells in seven different sites where the rapid formation of collagenous tissues is known to occur. It is clear that the chondrogenic cell is closely associated with the formation of cartilage matrix, which is composed of interwoven fibrils and an amorphous material which may act as a cementing substance. In the development of bone the organic matrix is laid down by the adjacent osteoblasts; intracytoplasmic filaments of these cells seem to be involved with this process, and it appears that the filaments may become extracellular and form part of the bone matrix. In tissue that is growing under tension (cf. osteoblastic layer of the periosteum) the cytoplasmic filaments are predominantly alined in layers within the cells; by sectioning in known planes it is apparent that the structures are of a filamentous nature and are not at present consistent with the form of membranes or tubules. The evidence presented strongly suggests that the intracytoplasmic filaments are concerned with fibrogenesis; various possibilities of the relationship between these filaments and the fully developed tissues are discussed.