Sample records for telophase
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Sample records 1 - 5 shown.



1

Meiose e viabilidade polínica na família Araceae/ Meiosis and pollen viability in Araceae family

Corrêa, Maria Goreti Senna; Viégas, Judith; Silva, João Baptista da; Ávila, Paula Fernanda Vaz de; Busato, Gustavo Rossato; Lemes, Jaqueline Schneider
2005-06-01

Resumo em português O objetivo deste trabalho foi analisar a microsporogênese e a viabilidade dos grãos de pólen em 17 espécies de aráceas coletadas no Rio Grande do Sul, Brasil. Nove espécies foram analisadas quanto à ocorrência de células mãe de pólen (CMP) normais e anormais nas fases de metáfase, anáfase e telófase, tanto da meiose I (M I) como da meiose II (M II); 10 espécies foram estudadas quanto à presença de tétrades com número normal ou anormal de micrósporos e (mais) 17 espécies quanto à viabilidade dos grãos de pólen. As CMP anormais apresentaram, tanto em M I quanto em M II, cromossomos fora da placa metafásica ou cromossomos retardatários em anáfase e/ou telófase. As freqüências de CMP normais/anormais encontradas na microsporogênese salientam a grande variação existente entre as espécies. Ressalta-se a ausência de CMP com anomalias na microsporogênese de Monstera deliciosa Adans., assim como em M I de Anthurium scandens (Aubl) Engl. e em M II de Caladium hortulanum Birdsey. O número observado de CMP anômalas, em M I e M II, nas espécies Syngonium podophyllum Schott e Zantedeschia aethiopica Spreng, foi maior que o esperado. A freqüência média de tétrades normais em dez espécies de aráceas, assim como a de grãos de pólen viáveis em 17 espécies, foi significativamente superior à freqüência média de anormais e de inviáveis, respectivamente. Resumo em inglês The objective of this work was to analyze microsporogenesis and pollen viability in 17 species of the Araceae family collected at Rio Grande do Sul, Brazil. Occurrence of normal and abnormal pollen mother cells (PMC) was analyzed in metaphase, anaphase and telophase, in meiosis I (M I) and meiosis II (M II) of nine species; tetrads with normal or abnormal number of microspores was observed in 10 species, and pollen grain viability, in 17 species. Abnormal PMC presented ch (mais) romosomes outside the metaphasic plate or laggard chromosomes in anaphase and/or telophase in both M I and M II. The frequencies of normal/abnormal PMC found in microsporogenesis point out to the existence of great variation among the species. It should be emphasized the absence of PMC with abnormalities in Monstera deliciosa Adans. microsporogenesis, as well as in Anthurium scandens (Aubl) Engl. M I and in Caladium hortulanum Birdsey M II. The number of anomalous PMC in Syngonium podophyllum Schott and Zantedeschia aethiopica Spreng in M I and M IIwas higher than expected. Average frequency of normal tetrads in ten araceous species and viable pollen grains in 17 species were significantly superior to the average frequency of abnormal tetrads and unviable pollen grains, respectively.

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2

Observações citológicas em Coffea: XV - Microsporogênese em Coffea arabica L.

Mendes, A. J. T.
1950-03-01

Resumo em português No presente trabalho são apresentadas as observações realizadas sôbre a microsporogênese nas variedades semperflorens e caturra, de Coffea arabica L. Notou-se que, no início da prófase, os cromossômios se colorem muito mal, não permitindo observações sôbre a sua morfologia; em paquitene, os cromossômios se apresentam com várias secções heteropicnóticas separadas por secções muito finas, que se colorem mal; o centrômero é bastante nítido e se acha lad (mais) eado de zonas bem heteropicnóticas; as extremidades dos braços dos cromossômios se colorem mal e se perdem no meio do citoplasma ; o nucléolo é bastante visível e a êle se acham ligados alguns cromossômios. É difícil determinar o número exato de cromossômios ligados ao nucléolo, tendo-se encontrado de 1 a 4. De paquitene a metáfase I, as fases se sucedem rapidamente. Em diplotene, os cromossômios são curtos, não mais se percebendo o centrômero. Em diaquinese os 22 pares de cromossômios se repelem pela sua parte mais colorida, onde se encontra o centrômero, e se unem pela parte clara, onde se notam os quiasmas ; o número de quiasmas, por célula, varia de 29 a 43 ; a média por bivalente é de 1,67, em semperjlorens, e 1,75, em caturra. Em metáfase I, o número médio de quiasmas, por bivalente,. é de 1,69, em semperjlorens, e 1,67, em caturra. Em anáfase I, os 22 pares de cromossômios se separam normalmente. Em telófase I, os cromossômios se colorem mal. Não há, praticamente, intercinese; os cromossômios contraem-se de novo e entram em anáfase II. A formação dos micrósporos é normal. Depois de soltos, ocorre a divisão nuclear, dando origem a dois núcleos com 22 cromossômios. Isto ocorre três a quatro dias antes da abertura das flores; o núcleo vegetativo é grande, esférico e homogêneo, colo-rindo-se mal; o núcleo reprodutivo é menor, reticulado, colore-se bem e se localiza na periferia da célula; ao seu redor se destaca uma porção de citoplasma, de forma lenticular. A divisão do núcleo reprodutivo geralmente se dá no tubo polínico. Tanto o núcleo vegetativo como o reprodutivo pode ser encontrado na extremidade do tubo polínico. Poucas irregularidades foram observadas na distribuição dos cromossômios, tendo, a grande maioria dos gâmetas, n=22 cromossômios. Resumo em inglês This paper presents results of cytological observations on microsporogenesis of the semperflorens and caturra varieties of the species Coffea arabica L. In general meiosis was found to be normal, the gametes having n = 22 chromosomes. Only minor irregularities were observed and these were limited to distribution of the chromosomes. In the early prophase of meiosis the chromosomes did not stain well. In the pachytene stage the chromosomes stained comparatively well and sho (mais) wed several hetero-piknotic regions separated by very fine sections which stained faintly. The centromere was readily seen and was located between two heteropiknotic sections. The extremities of the arms of the chromosomes stained very poorly and were lost to view in the cytoplasm. The nucleolus was easily visible and some of the chromosomes appeared to be attached to it. The exact number of chromosomes that were attached to the nucleolus appear to vary from one to four. From the pachytene stage the chromosomes passed very rapidly to metaphase I. In the diplotene stage the chromosomes were observed to be very short and the centromeres could not be seen. In the diakinesis stage the darkest colored parts of the 22 pairs of chromosomes, especially where the centromeres were located, were well separated indicating that they repelled each other. In contrast the slightly stained regions of the chromosomes were intimately associated and showed chiasmata. The number of chiasmata per cell varied from 29 to 43, the average per bivalents being 1.67 in semperflorens and 1.75 in caturra. In metaphase I the average number of chiasmata per bivalent was determinated as 1.69, in semperflorens and 1.67 in caturra. In anaphase I the 22 pairs of chromosomes were normally separated and in telophase I the chromosomes did not stain well, again making detailed observations difficult. Practically no interkinesis was observed. Following telophase I the chromosomes were observed to contract and entered into anaphase II, that was observed to be normal. The formation of microspores appeared to be normal. After separation of the microspores there occured a division of the nucleus giving origin to two nuclei with 22 chromosomes each. This was observed ot occur three to four days before opening of the flowers. The vegetative nucleus was observed to be large, round, homogeneous, and stain only faintly. The reproductive nucleus was observed to be small, reticulated ; it stained well, and was located at the periphery of the cell. The reproductive nucleus was usually found to be surrounded by a small amount of cytoplasm in a lenticular shape. The division of the reproductive nucleus usually takes place in the pollen tube. Both vegetative and reproductive nuclei were observed to occur in the extremity of pollen tube.

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3

Um estudo citológico comparativo de Thalictrum e Ilex

Jensen, Henry Wilhelm
1943-08-01

Resumo em inglês 1. New chromosome numbers have been determined tor the following species from material collected in various counties of North Carolina, U . S . A. Thalictrum clavatum n = 7 Th. dioicum n = 14 Th. polygamum n = 42 Th. coriaceum n = 70 Ilex decidua n = 20 I. monticola n = 20 I. vomitoria n = 20 I. opaca n = 18 I. verticillata n = 11. New chromosome numbers have been determined tor the following species from material collected in various counties of North Carolina, U.S.A. Th (mais) alictrum clavatum n = 7 Th. dioicum n = 14 Th. polygamum n = 42 Th. coriaceum n = 70 Ilex decidua n = 20 I. monticola n = 20 I. vomitoria n = 20 I. opaca n = 18 I. verticillata n = 18 2. The genus Thalictrum has been rather well investigated cytologically but the genus Ilex has not yet received the attention it merits, and offers cytologists in North, Central, and South America an opportunity ro study an extensive genus which has been, and probably is, undergoing interespecific hybridization while a shift from the hermaphroditic to the unisexual habit is also well established. These two great evolutionary factors, hybridization and the advent of the dioecious condition, appear to stimulate divergent lines of meiotic behavior depending upon whether or not they appear in the phylogeny of a race simultaneously or successively, and in the case of the latter, which came first. The genus Thalictrum was used as a basis for comparison with the situation as found in the eastern North American forms of Hex with the following conclusions. a. The genus Thalictrum is vastly polyploid and meiotically regular. This condition is thought to be the result of previous hybridization of the species before the advent of the dioecious habit. b. The genus Ilex is, as far as research has gone, negatively aneuploid and frequently irregular meiotically. This condition is thought to be the result of previous hybridization of the species after , or no more than simultaneously with, the advent oí the dioecious habit. Heterochromosome Complex Division in first seen Choromatin ejected Other diagnostic hybrid characteristics Species Type of Chromosome I.. decidua Medium Homeotypic One choromatid during second anaphase Laggards anaphase bridges I. monticola. Smallest member of complement Heterotypic One chormatid during first anaphase. Left in cytoplasm Lagging Precocious chorm I. opaca Medium Heterotypic Whole chorm. One chromatid sometimes accepted by complement in second div. Lagging chrom I. verticillata Two types. One tripartite X-- X1Y2 small Other medium Heterotypic Yes. Degenerates during first telophase. Yes Degenerates during first telophase. I. vomitoria Medium sized tripartite complex Heterotypic None found A number of laggards dur-first division 3. Heterochromosomes were found in microsporogenesis of all five species of Ilex, along with other meiotic peculiarities of suggested hybrid origin, but no two were alike. Behavior of the heterochromosomes was not found to be consistent and in approximately 5 0% of the PMCs. meiosis was normal. Findings are summarized in following table.8 4. In view of the generally ¡rabie chromosome number for the five species of Ilex investigated, only such pollen as arises from PMCs. which possess the normal meiosis may produce the gametes which effect fertilization. This presents the problem of explaining how the ability to produce meiotic abnormalities is inherited through cells which dcnot exhibit it or through the female side and its significance on the whole question of the evolution of sex chromosomes from various types of heterochromosomes. 5. A comparison of the cytology or species of Thalictrum and Ilex adds support to the author's earlier contention that so-called sex chromosomes in higher plants have their origin in special types of heterochromosomes which in turn owe their appearance to meiotic disturbances induced by previous hybridization of the species and preserved through the more or less simultaneous advent of the dioecious habit. In the author'- opinion, the genus Ilex offers an opportunity to increase our knowledge of what occur? during the stage intermediate between autosome and the specialized types of sex-linked heterochromosomes.

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4

Sôbre a meiose de Dysdercus mendesi bloete (1937) - Hemiptera, pyrrhocoridæ

Mendes, Luiz O. T.
1947-01-01

Resumo em inglês 1 - The spermatogonia of Dysdercus mendesi Bloete have 16 chromosomes : 7 pairs of autosomes and 2 sex-chromosomes. 2 - After the last spermatogonia! division, the chromatin of the autosomes diffuses and the nucleoplasm assumes an uniform granulai- aspect ; each sex-chromosome is involved by a vesicle and stands well colored. 3 - While the chromatin of the autosomes starts to condense again, to form the long threads (that finnally are seen in a paired condition) the cycle (mais) of the sex-chromosomes is as follows : a) yet contained in the vesicles, they grow in size and become long rods ; b) the vesicles disappear, the sex-chromosomes move inside the nucleoplasm and come to be disposed longitudinally, close together. c) they touch each other, become fissured, and a tetradlike chromatic element is formed, which contracts itself, remaining always well colored. 4 - The hetero-pycnosis of the sex-chromosomes is observed through the whole grow phase of the spermatocyte I. 5 - The separation of the sex-chromosome tetrad, originating two independent sex-chromosomes, is observed in the early grow phase of the spermatocyte as well as during any other period of this phase. The latest separation is observed during the diffuse stage of the nucleus. 6 - When the autosomes are in diakinesis, the sex-chromosomes assume the aspect of chromosomes in pachytene. 7 - In metaphase I the autosomic tetrads are in a more condensed and colored condition than the sex-chromosomes. The sex-chromosomes move to the center of the autosome-forming circle, but there is no contact between them. 8 - In anaphase I it is observed 2 interzonal connections between each autosomic dyad ; some exceptions are observed. Only one interzonal connection is observed between the separating sex-chromosomes. Moving to the poles the sex-chromosomes also approximate one to the other. 9 - In telophase I the sex-chromosome touch each other, and fuse side-by-side, forming only one chromatic element. The line of fusion is well visible through the subsequent stages of meiosis. 10 - In metaphase II the autosomes are disposed at the equator. The sex-chromosome, dyad is also disposed at the equator, as well as at any other position. 11 - In anaphase II the separation of the auto.somes is normal, and it is seen only one interzonal connection between its halves. The sex-chromosome dyad do not separate and moves to one pole, always in precession. 12 - There are two classes of spermatids : a) with 7 autosomes ; b) with 7 autosomes plus the sex-chromosome dyad. 13 - During the first phases of the spermatogeneses the 7-autosomc containing nucleus presents a reticulated aspect ; the sex-chromosome-dyad containing nucleus shows this chromatic element well colored inside the reticulated nucleoplasm. 14 - The male of Dysdercus mendesi Bloete has 7 AA + XX chromosomes. NOTE - A discussion on the movements of the sex-chromosome and its cycle. as well as on some aspects of the pairing of the autosomes, is being prepared. It will be published in the near future. The female of Dysdercus mendesi Bloete has 2n = 14A+4X.

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5

Anomalias meióticas de oócitos de pacientes com endometriose submetidas à estimulação ovariana/ Meiotic abnormalities of oocytes from patients with endometriosis submitted to ovarian stimulation

Barcelos, Ionara Diniz Evangelista Santos; Vieira, Rodolpho Cruz; Ferreira, Elisa Melo; Araújo, Maria Cristina Picinato Medeiros de; Martins, Wellington de Paula; Ferriani, Rui Alberto; Navarro, Paula Andrea de Albuquerque Salles
2008-08-01

Resumo em português OBJETIVO: avaliar o fuso meiótico e a distribuição cromossômica de oócitos maturados in vitro, obtidos de ciclos estimulados de mulheres inférteis com endometriose e fatores masculino e/ou tubário de infertilidade (Grupo Controle), comparando as taxas de maturação in vitro (MIV) entre os dois grupos avaliados. MÉTODOS: quatorze pacientes com endometriose e oito com fator tubário ou masculino, submetidas à estimulação ovariana para injeção intracitoplasmát (mais) ica de espermatozóide, foram selecionadas, prospectiva e consecutivamente, e constituíram os Grupos de Estudo e Controle, respectivamente. Oócitos imaturos (46 e 22, respectivamente, dos Grupos Endometriose e Controle) foram submetidos à MIV. Oócitos que apresentaram a extrusão do primeiro corpúsculo polar foram fixados e corados para avaliação dos microtúbulos e cromatina por técnica de imunofluorescência. A análise estatística foi realizada utilizando o teste exato de Fisher, com significância estatística quando p Resumo em inglês PURPOSE: to evaluate the meiotic spindle and the chromosome distribution of in vitro mature oocytes from stimulated cycles of infertile women with endometriosis, and with male and/or tubal infertility factors (Control Group), comparing the rates of in vitro maturation (IVM) between the two groups evaluated. METHODS: fourteen patients with endometriosis and eight with male and/or tubal infertility factors, submitted to ovarian stimulation for intracytoplasmatic sperm injec (mais) tion have been prospectively and consecutively selected, and formed a Study and Control Group, respectively. Immature oocytes (46 and 22, respectively, from the Endometriosis and Control Groups) were submitted to IVM. Oocytes presenting extrusion of the first polar corpuscle were fixed and stained for microtubules and chromatin evaluation through immunofluorescence technique. Statistical analysis has been done by the Fisher's exact test, with statistical significance at p

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