arrangement of microtubules in embryos derived from mice young, old and reconstructed oocytes

To study the structure and distribution of microtubules in embryos derived from young, old and reconstructed oocytes. Embryos obtained from old [50 embryos], young [50 embryos] and reconstructed oocytes [10 embryos] were studied by immunocytochemistry. The microtubule structures of the embryos were studied by using fluroscent microscopy with FITC-PI filter and polyclonal antibody against alfa tubulin. The spindle structure of MII young oocyte and the obtained embryos were normal with the suitable condensation. There was no contact between chromosome and spindle in old Oocytes as well as the obtained embryos, in addition, the spindle was extended in old group. In reconstructed embryos, thin and scattered filaments were observed. This study reveals that the arrangement of microtubules in reconstructed embryos was caused by repeating of injection and oocyte manipulation. Also, interactions between karyoblast, cytoplasm and microtubuls may not be suitable. This may be caused by low fertilization in these oocytes

Microtubule cytoskeleton distribution using fluorescent taxoid in tetratrichomonas didelphidis

Tetratrichomonas didelphidis is a flagellated protozoan found in the intestine of opossums. The specimens were stained by the Giemsa method and by FLUTAX-2, an active fluorescent derivative of Taxol which binds to the ab-tubulin polimerized of microtubules of cells. Giemsa stain revealed the morphological features of trichomonads such as four anterior flagella, undulating membrane, axostyle and posterior flagellum. An intense fluorescence was observed in living trophozoites of T. didelphidis and Trichomonas vaginalis (used as control), incubated with FLUTAX-2. An analysis of the composition of the cytoskeleton of T. didelphidis will contribute to understanding the cellular morphology of the parasites. Key words: Tetratrichomonas didelphidis, microtubule cytoskeleton, fluorescent taxoid.

Tubular Aggregate Myopathy: A Case Report

We report a first Korean case of presumably dominantly inherited primary tubular aggregate myopathy in a 19-yr-old man, who presented with slowly progressive proximal muscle stiffness and weakness. In hematoxylin and eosin stain, it showed subsarcolemmal, or central pale basophilic granular vacuoles, which stained red with modified Gomori's trichrome and intensive blue with nicotinamide adenonine dinucleotide-tetrazolium reductase, respectively. Ultrastructurally, aggregates of 60 nm-sized hexagonal tubules were found in both type 1 and type 2 fibers. We briefly review the pathologic findings of the previously reported cases of tubular aggregate myopathy and discuss the possible pathogenesis of this disease. We briefly discuss the possible pathogenesis of sarcoplasmic reticulum and review the ultrastructural characteristics.

Behaviour of microtubules in cells infected with Toxoplasma gondii

Toxoplasma gondii proliferates within the parasitophorous vacuole of the host cell. Simultaneously with parasite division and vacuolar development, lipids traffic and change in the spatial distribution of organelles of the host cell cytoplasm occur. Using fluorescence microscopy, and antibodies recognizing tubulin, we showed that microtubules change their distribution during host cell infection by tachyzoites of T. gondii. In addition, transmission electron microscopy of thin sections and replicas of partially extracted cells showed that host cell microtubules concentrate around the parasitophorous vacuole. Such microtubules distribution was evident in early infection times and was more prominent after 24 h of infection, when parasitophorous vacuole was completely surrounded by microtubules. However, the meshwork microtubule filaments became slack or absent after 72 h of infection of host cell. Colchicine and taxol treatment altered the shape of the parasitophorous vacuole containing tachyzoites. These observations suggest a close association between microtubules and intravacuolar development of parasites.

Dysmyelination, demyelination and reactive astrogliosis in the optic nerve of the taiep rat

Taiep is an autosomal recessive mutant rat that shows a highly hypomyelinated central nervous system (CNS). Oligodendrocytes accumulate microtubules (MTs) in association with endoplasmic reticulum (ER) membranes forming MT-ER complexes. The microtubular defect in oligodendrocytes, the abnormal formation of CNS myelin and the astrocytic reaction were characterized by immunocytochemical and ultrastructural methods during the first year of life. Optic nerves of both control and taiep rats were processed by the immunoperoxidase method using antibodies against tubulin, myelin basic protein (MBP) and glial fibrillary acidic protein (GFAP). Taiep oligodendrocytes are strongly immunoreactive against tubulin, indicative of a significant accumulation of microtubules. Early differentiated oligodendrocytes observed with electron microscopy show that MT-ER complexes are mainly present in the cell body. This defect increases during the first year of life; oligodendrocytes show large MT-ER complexes projected within oligodendrocyte processes. Using anti-MBP, there was a progressive reduction of immunolabeling in the myelin sheaths as taiep rats grew older. Ultrastructural analysis revealed severely dysmyelinated axons with a frequently collapsed periaxonal collar. However, through age the myelin sheath became gradually infiltrated by MTs, suggesting their contribution to premature loss of myelin in the taiep rat. Axons of one-year-old taiep rats were severely demyelinated. Modifications in astrocytes revealed by the GFAP antibody showed a strong hypertrophy with increased immunostaining in their processes. As demyelination of axons progressed, taiep rats developed a strong astrogliosis. The present findings suggest that in taiep rats the early abnormal myelination of axons affects the adequate maintenance of myelin, leading to a progressive loss of myelin components and severe astrogliosis, features that should be considered in the pathogenesis of dysmyelinating diseases

Peripheral nerve sheath tumours: an ultrastructural study of 30 cases.

This report deals with the ultrastructural observations of 30 peripheral nerve sheath tumours [PNST], which include 25 schwannomas of acoustic nerve, one schwannoma of cauda equina, one neurofibroma from a case of Von Recklinghausen's disease, one pigmented neurofibroma of spinal nerve root and a malignant schwannoma of frontal region. Interdigitating slender cytoplasmic processes covered with a continuous layer of basal lamina constitute the single most important ultrastructural attribute of Schwann cells. Myelin formation was encountered in the cell processes of four out of 25 acoustic schwannomas. In four cases Microtubular arrays identical to that in an axon were seen in Schwann cells. These two observations require further support by additional cases of PNST studies by electron microscopy. The neurofibroma consisted only of Schwann cells and no ultrastructurally identifiable perineurial cells or fibroblasts were detected. The cells in the pigmented neurofibroma revealed submicroscopic features of both Schwann cell and melanocyte, indicating their common ancestry. A unique case of malignant schwannoma arising from frontal meninges is illustrated and it is emphasized that electron microscopy is mandatory for a correct histogenetic diagnosis of malignant tumours which occur at unexpected anatomical sites.

Post-metaphase mitotic events in cells treated with dinitrophenol.

The sequence of post-metaphase mitotic events, such as anaphase movement A and B, chromosome decondensation, nuclear envelope reformation and cytokinesis, has been studied in 2,4-initrophenol (DNP)-treated HeLa cells. The effects of DNP were found to be dose dependent and at concentrations higher than 3 mM, both anaphase A and B movements were totally and nearly instantaneously arrested. It could be shown that cytokinesis did not depend on the completion of anaphase movements. This was also true for nuclear envelope reformation which could take place even around condensed chromosomes arrested in anaphase. The post-metaphase mitotic events do not follow a strict causal sequence, but they can be dissociated from each other in anaphase-arrested cells.

Effect of low body temperature of the microtubles of toad brain and testes studied with a morphometric and a biochemical method

El análisis morfométrico aplicado a fibras preterminales de cerebro y a células de Sertoli de testículo del sapo Bufo arenarum mostraron que los microtúbos desaparecen en un 75% y 92% respectivamente cuando los animales son enfriados a 1-2-C por 90 minuots. Las estimaciones hechas en cuerpos neuronales de cerebro y en otras células del testículo mostraron los mismos resultados. Trabajos previos de los autores (López y Bertini, 1982) mostraron que el grado de polimerización de tubulina (porcentaje de tubulina insoluble) en sapos enfriados, solo decreció en un 40%. Se postula que el elevado porcentaje de tubulina insolubre en animales enfriados es decreció en un 40%. Se postula que el elevado porcentaje de tubulina insoluble en animales enfriados es debido a la existencia de un pool de tubulina no estructurada en microtúbulos, unida a estructuras membranosas en sitios de alta afinidad y/o a oligómeros de tubulina no reconocible como microtúbulos por microscopía electrónica

Effect of ADH on the toad efferent ducts

La ADH produce la reabsorción de fluidos en el aparato renal y en el tracto reproductor masculino de los mamíferos. Los conductos eferentes tienen origen mesonéfrico y están relacionados con ambos sistemas. Se estudió el efecto de la ADH, sobre los conductos eferentes del sapo y los cambios ultraestructurales. Las áreas citoplásmicas y nucleares de las células epiteliales aumentaron. Los núcleos se hicieron más claros, con disminución de la heterocromatina y profundos pliegues de sus envolturas. Es evidente un aumento del número de vesículas citoplásmicas, muchas de las cuales se abren a los espacios intercelulares y están asociadas con microfilamentos y microtúbulos. Estos hallazgos podrían indicar un aumento en el transporte de agua y sodio. Existe un probable efecto directo de la ADH en los conductos eferentes del sapo