Showing papers on "Ultrastructure published in 1971"

Host-Parasite Interrelationships Between the Freshwater Pulmonate Biomphalaria Pfeifferi and the Trematode Schistosoma Mansoni

Abstract: The influence of infection with S. mansoni on reproduction, growth, food consumption and survival in B. pfeifferi was studied experimentally (Ch. II). The prepatent period in infected snails was shown to last 22-24 days under the conditions prevailing in the relevant experiment. The number of eggs laid by infected snails as compared with controls was significantly reduced from 7-10 days postinfection onwards. After day 13 postinfection it was completely suppressed in the majority of the infected snails. The increase in shell diameter in infected specimens was larger than that of the controls between 7 and 18 days, that in weight between 11 and 21 days postinfection. Gigantism did not occur. There was no difference in mortality between infected and control snails prior to the 11th week after the beginning of the experiment. After that, the mortality among infected specimens showed a sharp rise. Uninfected and infected snails consumed similar amounts of food (dried lettuce) in the first two weeks of the experiment. After that, infected snails consumed less food than controls. The digestive gland of B. pfeifferi was studied with histological, histochemical and ultrastructural methods (Ch. III). The highly folded epithelium of the ducts connecting the digestive gland with the pyloric part of the stomach, consists of cilia and/or microvilli bearing columnar cells with interspersed mucous cells. In the epithelium of the digestive gland two main cell types are distinguished: the digestive cell and the secretory cell. In addition some mucous cells occur. It is concluded that the main functions of the digestive cell are absorption and endocytosis of predigested food material, followed by intracellular digestion. Indigestible residues are accumulated in a large vacuole, which eventually is excreted. The secretory cell produces and secretes proteinaceous substances, presumably digestive enzymes. It does not store calcium. The so-called excretory cells, which are in fact degenerating secretory cells, have vacuoles containing yellow globules. These yellow globules together with cell debris are finally released into the lumen of the digestive gland. The observations indicate that the digestive gland is not important as a storage organ for reserve material. The lobules of the digestive gland are covered by a thin connective tissue sheath, consisting of ground substance, collagen-like fibrils, smooth muscle cells and cells with the appearance of pigment cells. The connective tissue between the lobules of the digestive gland and the acini of the ovotestis, and between these organs and the mantle, consists mainly of vesicular connective tissue cells. These cells are supposed to play an important metabolic role as storage cells for glycogen. The tegument of the daughter sporocyst of S. mansoni (Ch. IV), consisting of an outer syncytial anucleate layer which is joined by cytoplasmic connections to nucleated cell bodies (tegumental cells), has the same basic architecture as that described for various stages of trematodes and cestodes. Well-developed mitochondria, GER cisternae and tubules, free ribosomes and polysomes, and lipid droplets occur throughout the tegument. The ultrastructural features suggest that the outer layer is involved in uptake of nutrients by absorption and endocytosis. The poorly developed musculature is loosely arranged in two layers beneath the outer tegumental layer. The nucleated portions of the muscle fibres are situated between the tegumental cells. The protonephridial system consists of flame cells with efferent tubules. The bundle of cilia, implanted in the flame cell, beats in the cilia chamber or barrel. The proximal part of the barrel consists of alternating rib-like extensions of the flame cell and of the first tubule cell, respectively. Ultrafiltration probably takes place in the ribbed part of the barrel. The development of cercariae from germinal cells is briefly described. The pathological effects of infection with S. mansoni on the digestive gland epithelium of B. pfeifferi (Ch. V) are limited. From about 12 weeks after infection slight changes occur, but they are difficult to distinguish from changes due to ageing of the cells. The effect of starvation on the digestive gland epithelium is much more marked than the adverse influence of infection. Compression of digestive gland lumina by daughter sporocysts was not observed. Changes in the connective tissue of the digestive gland due to the presence of daughter sporocysts were: development of muscle cells into cells with the appearance of pigment cells and/or degeneration of these muscle cells, and an increase in the number of amoebocytes, which become involved in the elimination of cell debris and in the formation of a loose layer over the parasites.

Ultrastructural evidence of polarized synapses in the nerve net of Hydra.

Abstract: Synapses provide pathways of communication between cells throughout the animal kingdom wherever a nervous system is present. The most primitive or elementary nervous system that can be readily recognized is the nerve net of coelenterates . The first synapses described at the ultrastructural level in nerve net animals were symmetrical synapses in marginal ganglia of jellyfish (Horridge and Mackay, 1962) . Later, two types of synapses were reported (Jha and Mackie, 1967) in a hydromedusan, Sarsia : (a) symmetrical synapses with vesicles on both sides of a specialized membrane and (b) asymmetrical synapses with vesicles on only one side of the synaptic junction. Asymmetrical or morphologically polarized synapses have now been demonstrated ultrastructurally in a sea pen (Buisson and Franc, 1969 ; Buisson, 1970), a primitive hydromedusan (Westfall, 1970 a), a sea anemone (Westfall, 1970 b), and various other species of Cnidaria (Westfall et al ., 1970) . The ultrastructural confirmation of neurons in Hydra by Lentz and Barrnett (1965) excited a number of investigators to the possibility of demonstrating synaptic contacts in this elementary nervous system. To date, there have been no reports of morphologically specialized contacts between cells of Hydra that might indicate the precise region of chemical mediation of an impulse (see Lentz, 1968) . In the present study ultrastructural evidence is provided for the presence of polarized interneuronal synapses and neuromuscular and neuronematocyte junctions in two species of Hydra .

Effects of colchicine on axonal transport and ultrastructure of the hypothalamo-neurohypophyseal system of the rat

Abstract: The effect of colchicine on the transport of proteins in the hypothalamo-neurohypophyseal tract of the rat was studied after injection of (35S) cysteine into the supraoptic nucleus (SON) region. Colchicine, dissolved in distilled water and administered subarachnoidally, inhibited the axonal transport of labelled proteins into the neurohypophysis: the radioactivity that was recovered in neurohypophyseal TCA precipitable material was markedly decreased and hardly any radioactivity was found in the neurohypophyseal proteins which were separated by polyacrylamide gel disc electrophoresis. As revealed by electron microscopy the SON cell bodies showed marked changes after treatment with colchicine: a deeply folded nucleolemma; a pronounced, granular nucleolus; a dispersed chromatin; a zonal distribution of cell organelles with mitochondria and lysosomes accumulated at the periphery, crowded ribosomes, often arranged as polyribosomes and richly branching short profiles of endoplasmic reticulum filled with filamentous material forming an inner perinuclear zone separated by enlarged Golgi complexes. The profiles of elongated Herring bodies in the infundibulum were increased. The axon terminals were filled with heavily osmiophilic neurosecretory granules. The neurofilaments were slightly or moderately increased in number. No apparent changes were observed with regard to the neurotubuli in the SON neurons. The glial cells of the supraopticoneurohypophyseal tract showed reactive changes with a proliferation of filamentous elements. The biochemical and ultrastructural findings are discussed especially with respect to the mechanisms of transport and release of neurosecretory granules.

Ultrastructure of the copper-accumulating region of the Drosophila larval midgut.

Abstract: The copper-accumulating region of the midgut is a mosaic of interstitial and cup-shaped, copper-accumulating cells. The cup of each cuprophilic cell is lined with a highly refractile border of long microvilli except in one strain where it is predominantly lamellar. The nucleus lies basally; the basal plasma membrane is fairly extensively infolded. Cytolysomes are abundant and increase in number with increasing copper content of the diet. The interstitial cells bear short, less regular microvilli and have a less electron-dense cytoplasm. The nucleus is apical, the mitochondria-associated basal membrane is very extensively infolded and cytolysomes are less abundant. Virus-like particles present in nuclei of both cell types increase in number with increasing copper concentration.

Ultrastructure of Cryptosporidium wrairi from the guinea pig.

Abstract: SYNOPSIS. The ultrastructure of the known tissue stages of Cryptosporidium wrairi Vetterling, Jervis, Merrill, and Sprinz, 1971 parasitizing the ileum of guinea pigs is described. Young trophozoites are surrounded by 4 unit membranes, the outer 2 of host origin, the inner 2 the pellicle of the parasite. Each trophozoite contains a vesicular nucleus with a large nucleolus. Its cytoplasm contains ribosomes, but eventually fills with cisternae of the rough endoplasmic reticulum. As the trophozoite matures the area of attachment of the parasite to the host cell becomes vacuolated, with vertical membranous folds. It is apparent that the parasite acquires nourishment from the host cell thru this area of attachment. As schizonts develop, (a) multiple nuclei appear, (b) the endoplasmic reticulum enlarges, (c) the attachment zone increases in area, (d) large vacuoles, which develop as endocytotic vesicles in the attachment area, are found in the cytoplasm and (e) the inner unit membrane of the parasite pellicle is resorbed around the sides of the developing schizont. Following nuclear division, merozoites develop from the schizont by budding. Merozoites have an ultrastructure similar to that described for other coccidia except that no mitochondria, micropores, or subpellicular tubules were observed. Merozoites penetrate the epithelial cell causing invagination of the microvillar membrane and lysing it. No unit membrane is formed between the parasite and the host cell. However, the cell produces one or 2 dense bands adjacent to the parasite attachment area. The macrogamete contains a nucleus, endoplasmic reticulum, attachment zone, and large vacuoles. It also contains a variety of granules, some of which are polysaccharide. The immature microgametocyte contains multiple compact nuclei. No mature microgametocytes or zygotes were found.

The ultrastructure of the salt gland of Spartina foliosa.

Abstract: The salt gland in Spartina foliosa is composed of two cells, a large basal cell and a smaller, dome-shaped cap cell which is located on a neck-like protrusion of the basal cell. There is no cuticular layer separating the salt gland from the mesophyll tissue. The basal cell has dense cytoplasm which contains numerous mitochondria, rod-like wall protuberances, and infoldings of the plasmalemma which extend into the basal cell and partition the basal cell cytoplasm. The protuberances originate on the wall between the basal and the cap cells and are isolated from the basal-cell cytoplasm by the infoldings of the plasmalemma. While the cap cell has no partitioning membrane system or wall protuberances, it resembles the basal cell by having dense cytoplasm and numerous mitochondria.The basal cell seems to be designed for efficient movement of ions toward the cap cell. The long, dead-end extracellular channels in the basal cell of Spartina appear comparable to surface specializations seen in the secreting epithelium of animal cells which carry out solute-linked water transport. The number of mitochondria and their close association with the plasmalemma extensions suggest that they have an important role in the transfer of ions through the basal cell.The accumulated ions would move into the extracellular spaces along an osomotic gradient where the accompanying passive flow of water would move the ions into the cap-cell wall and from there the solution would pass out through the pores in the cuticle.

The ultrastructure of four types of human spermatogonia

Abstract: Electron microscopic examination of normal human testes has revealed the ultrastructure of four types of spermatogonia. These are the dark type A (AD), the pale type A (AP), the type B (B), and a new type A (AL). The subcellular criteria used in distinguishing between these four spermatogonial types include the shape of the nucleus, the density of the nucleoplasm, the type of nucleolus and its placement within the nucleus, the structure of the mitochondrial cristae, the association of the endoplasmic reticulum with the mitochondria, the amount of glycogen present within the cell, and the presence of previously undescribed filamentous structures in the cytoplasm of the AL and AD spermatogonia. Each spermatogonium is in contact with the tubular basal lamina; the amount of contact progressively decreases from the AL, a flat cell lying parallel to the basal lamina, through the AD and AP to the B spermatogonia, the latter being a pear-shaped cell with its long axis perpendicular to the basal lamina.

Light and electron microscopy of the leucocytes of Crassostrea virginica (Mollusca: Pelecypoda).

Abstract: The fine structure of oyster leucocytes resembles to a great extent, that of typical eucaryotic cells. Organelles which have been described for the first time in this report are light granules, dense granules, protocentriole and X structure. Light microscopy reveals two morphological types of oyster leucocytes: agranular and granular. Based upon nuclear morphology and cytoplasmic compositions revealed in electron microscopy, at least three types of agranular and one type of granular cells are recognized.

Ultrastructure of granular cell ameloblastoma.

Abstract: To our knowledge, this is the first description of the ultrastructure of the granular cell ameloblastoma, an odontogenic tumor. The granular cells of this tumor are shown to be epithelial in origin. The organelles resulting in their cytoplasmic eosinophilia, as seen in the light microscope, are mainly pleomorphic, osmiophilic lysosome-like granules. A comparison with granular cell myoblastoma shows a striking morphological similarity between the cytoplasmic granules of these two lesions. We conclude that the granular cell ameloblastoma and the granular cell myoblastoma, probably along with the granular cell ameloblastic fibroma and the congenital epulis, constitute a group of lesions in which the lysosomes are the common denominator as the expression of their cytoplasmic eosinophilia.

An ultrastructural study of the neurosecretory cells of the medial vascular preiasmatic gland, the preoptic recess and the anterior part of the suprachiasmatic area. I. Cytoplasmic inclusions resembling nucleoi.

Abstract: A distinctive cytoplasmic inclusion, termed nucleolus-resembling body, was identified in the neurons, but not in the glial cells, of the medial vascular prechiasmatic gland, the preoptic recess and the anterior part of the suprachiasmatic area in the rat. This ultrastructure which lacks a limiting membrane is made of an entanglement of tightly packed filaments, 60–70 A in diameter. Each filament consists of smaller units, 15–20 A thick. Usually, only one such ultrastructure is present in a cell, but at time two were identified. It is present in most neurosecretory cells. It is surrounded by polyribosomes in the perikaryon of the nerve cells. Furthermore, it is linked to peripherally located ribosomes by means of filaments, 70 A in diameter. A possible function in protein synthesis of structural components, such as neurofilaments, is hypothesized. Two distinctive fibrillar areas were identified in the nucleolus according to the tightness with which fibrils were packed together. Their significance is discussed. Nucleolar extrusions were never observed in our studies. Paranucleolar and coiled bodies were identified in the nuclear sap. The mechanism of formation and the significance of these bodies are discussed.

The fine structure of the hepatopancreas of the woodlouse, Oniscus ascellus

Abstract: The present ultrastructural study of the hepatopancreas of Oniscus ascellus would seem to indicate that the entire gland functions as a true midgut and is involved in absorption and secretion. Two differentiated cell types, the S and B, are present throughout the gland except for a small area of the posterior or regenerative zone. Ultrastructural features that have been associated with absorption include the presence of a surface enteric coat, regularity of microvillar core filaments, an organelle free region under the microvilli and the uniform distribution of mitochondria below this area. These features are present in both the S and B cell types. Features that are typical of secretory cells include the presence of extensive arrays of parallel rough endoplasmic reticulum, the very active dictyosomes with dilated cisternae and large secretory bodies. These features are present in the B cell. Although occasional arrays of parallel endoplasmic reticulum were noted in the S cell, active dictyosomes with dilated cisternae were not evident. From this ultrastructural study it would appear that the B cell functions in absorption and secretion, while the S cell functions primarily in absorption. A cytochemical study is now in progress.

Scanning electron microscopy of the surface of the rat uterine epithelium during delayed implantation.

Abstract: Observations obtained by scanning electron stereoscopy on the ultrastructure of the surface of the luminal epithelium during the creation of a neutral state in the uterus where the animals were ovariectomized early in pregnancy and treated subsequently with progesterone alone. On the 10th-12th day postcoitum laparotomies were performed and uterine samples were removed and fixed. The samples were found to have sea-anemone-like formations occurring at frequent intervals. The tentacles were formed by an projected from a basal body. Occasionally the tentacles appeared completely flattened forming a circular compact mass with a hollow center. It is thought that these correspond to various stages of development. This organization suggests that such formations as cellular organelles with precise functions the significance of which should be of importance in the composition of the uterine milieu surrounding the dormant blastocyst.

Ultrastructure of cultured fibroblasts in I-cell disease.

Abstract: Cultivated skin fibroblasts from patients with I-cell disease and one patient's parents were investigated by light and electron microscopy Abundant membrane-bound inclusions, apparently within lysosomes, were found in cultured skin fibroblasts obtained from both patients Light and electron microscopy demonstrated that the inclusions were PAS positive, oil red O positive, metachromatic, and osmiophilic The inclusions were comprised of multivesicular and pleomorphic membranes, as well as homogeneous electron dense and electron translucent material Similar morphological abnormalities were noted occasionally in cells from the patient's father These morphologic abnormalities, persisting after many cellular generations in vitro, appear to be characteristic features of the I-cell phenotype

Ultrastructural changes of organelles in coleoptile cells during anaerobic germination of rice seeds

Abstract: Ultrastructural changes of organelles, especially those of mitochondria in rice seedlings germinated under strictly anaerobic conditions were investigated.

Ultrastructural changes in tobacco undergoing the hypersensitive reaction caused by plant pathogenic bacteria

Abstract: The hypersensitive reaction induced by either Erwinia amylovora or Pseudomonas pisi is indicative of widespread damage to membranes of subcellular organelles and particulate cellular components in tobacco leaf tissue. Plasmalemma, tonoplast, as well as the bounding and internal membranes of chloroplasts and mitochondria and the external membrane of microbodies, are profoundly deranged in 7 h. Cytoplasm, groundplasm of chloroplasts, mitochondria and microbodies and membrane-attached and free ribosomes are similarly affected. The damage coincides with and is probably the cause of the observed tissue collapse and rapid loss of electrolyte-laden water. The presence of few bacterial cells (not more than 4 × 106 cells/leaf disk 1 cm in diameter) cause the observed symptoms which appear, at the ultrastructural level, to be unique.

Ultrastructure of functioning beta cell tumors of the pancreatic islets

Abstract: Eight cases of functioning beta cell tumors with recurrent hypoglycemia, including 3 with metastases, were studied by electron microscopy. Based on their ultrastructure, the tumors were classified into 2 types. Type 1 was composed of cells with abundant typical beta granules which showed a close resemblance to the non-neoplastic beta cells of the pancreatic islets. Type 2 consisted mainly of cells without the typical granules, intermingling with a small number of cells which revealed a few, immature beta granules. Numerous dense granules resembling lysosomes were found in the majority of the cells. The cells of this type possessed extensive interdigitation of the cell membrane forming the intercellular spaces. Sometimes intracellular canaliculi were also found. Thus, it was demonstrated that the cells of type 2 tumors had morphological similarities to the cells of the terminal ductules of the pancreas. These results tend to suggest that the ultrastructure, including the formation of the secretory granules, reflects the stages of differentiation of the tumor cells.

Ultrastructure of a cloned astrocytoma in tissue culture.

Abstract: The ultrastructure of a cloned astrocytoma line which produces a protein unique to the nervous system (S-100 protein) is described. The cells have features that are consistent with an origin from neoplastic astrocytes. They are characterized by a sparsity of organelles and the presence of many fine filaments in their cytoplasm. Two classes of filaments are present. One type is 90 to 100 A in diameter filaments that frequently appear hollow, are gently curved, can be followed for long distances in thin sections, and are arranged in loose fascicles. These filaments are similar to the cytoplasmic filaments in normal and neoplastic astrocytes in vivo but are more loosely arrayed in TC-158 cells than in normal astrocytes. The other type is 70 to 75 A filaments that are uniformly electron dense, straight, can only be followed for short distances in sections, and are arranged in compact bundles. These filaments are without counterpart in normal or neoplastic astrocytes in vivo although they are frequently seen in cultured cells from diverse origins (so-called “stress fibers”). In TC-158 cells examined with the light microscope, PTAH-stainable fibrils are present that mimic the distribution of the fine bundles of 70 to 75 A filaments seen in the electron microscope. We suggest that the PTAH-stainable fibrils and bundles of 70 to 75 A filaments share a common identity in TC-158 astrocytes. Although PTAH-staining fibrils in cultured astrocytes have been called “gliofibrils” in the literature, our results indicate that they are analogous to the “stress fibers” which are a nonspecific finding when present in cultured cells.

On the histochemistry and ultrastructure of the redia of Neophasis lageniformis (Lebour, 1910) (Trematoda, Acanthocolpidae)

Abstract: The redia of Neophasis lageniformis within the first intermediate host, the carnivorous prosobranch Buccinum undatum, has been studied by means of light microscope and scanning and transmission electron microscopes. The tegument of the redia is provided with irregular cytoplasmic projections or microvilli-like structures and knobs. Short cilia occur around the mouth and long cilia on the lateral surface. Numerous pinocytotic vesicles in the intestinal cells and in the tegument show that absorption of nutrients takes place through both the intestinal caecum and the external surface. The fine structure of the body wall of the redia is discussed and compared with previous investigations of the ultrastructure of germinal sacs. Histochemical tests showed that the tegument and subtegumentary layer contain acid and alkaline phosphatases, non-specific esterase, and aminopeptidase. The intestinal lumen contains a high concentration of acid phosphatase, and the pharynx is highly non-specific esterase-posit...

Ultrastructure of the differentiated cell colony derived from a singly isolated chondrocyte in in vitro culture.

Abstract: The ultrastructure of differentiated colonies developed in vitro from singly isolated chondrocytes of the sterna of chicken embryos were studied by an improved method for cutting ultra-thin sections for electron microscopy in a plane normal to the plastic substrate. The differentiated colony consisted of a central refractile portion with a metachromatic matrix and a peripheral monolayered ring. Electron microscopic observation of thin sections showed a large central lumen which seems to be filled with cartilaginous matrix and collagen. Its roof is a thin layer of cells, in which the cells come together rather compactly, while the floor of the lumen consists of a monolayer, in which conical cells adhering to the substrate were loosely distributed. Most cells in the central portion are rich in granular endoplasmic reticulum with prominent saccular cisternae and large vacuoles presumably derived from Golgi complexes. The cells adhering to the substrate are actually in contact with it at only a few points across a gap of 40–200 A. The rest of the cell surface is free of the substrate.

Ultrastructure of Harpochytrium Hedinii

Abstract: An ultrastructural study of growth and reproduction of Harpochytrium hedinii Wille is presented. The fine structure of the zoospore and its subsequent development to a mature thallus reveals a rema...