466 resultados para ovule ontogeny


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Brosimum gaudichaudii Trécul, popularmente conhecida como mama-cadela, é uma espécie arbórea comum nos cerrados brasileiros, de grande importância na alimentação e na medicina popular. A polpa amarela dos frutos é muito apreciada pelas crianças por ser semelhante à goma de mascar. Neste trabalho é apresentada a caracterização morfoanatômica e histoquímica da inflorescência, fruto e semente de B. gaudichaudii. O material foi processado segundo técnicas usuais para estudos anatômicos e ultra-estruturais. As inflorescências são captadas, globosas, pedunculadas, pendentes, predominantemente aos pares nas axilas foliares e recobertas por brácteas peltadas densamente pilosas. Cada inflorescência é composta por várias flores masculinas e uma flor feminina. As flores masculinas são constituídas por um estame envolvido por bractéolas. A flor feminina é constituída por um pistilo com ovário ínfero penta-carpelar, entretanto um só lóculo se desenvolve. É comum a presença de dois óvulos no lóculo desenvolvido; entretanto somente um óvulo se desenvolve em semente. O óvulo é pêndulo, hemianátropo e bitegumentado apenas na região micropilar. No fruto maduro, identificam-se: a polpa, correspondente a parte comestível, e endocarpo; na semente, o tegumento é membranáceo e o embrião não apresenta endosperma secundário. O tecido parenquimático da polpa apresenta muitos espaços intercelulares, repletos de conteúdo aquoso. O endocarpo é esclerificado e encontra-se bem diferenciado no fruto maduro. Os laticíferos são do tipo não-articulado ramificado, com paredes espessas e ocorrem no receptáculo da inflorescência, são abundantes no pedúnculo e na polpa do fruto maduro e no embrião. Os idioblastos fenólicos estão distribuídos na inflorescência e no fruto.

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O hipotireoidismo congênito (HC) ocorre, mundialmente, em 1/3000-4000 neonatos e pode ser classificado em permanente ou transitório. O HC primário é responsável pela maioria dos afetados, enquanto o secundário e terciário são raros. Nos países iodo-suficientes, a disgenesia tireóidea (DT) é a causa mais freqüente de HC. Os defeitos hereditários da síntese hormonal ocorrem em minoria de crianças portadoras de HC. Fatores ambientais, genéticos e auto-imunes concorrem na etiologia do HC, mas na maioria dos casos de DT a causa é obscura. Atribui-se aos genes envolvidos na ontogenia da glândula tireóidea, como os fatores de transcrição TITF1, TITF2, PAX-8 e receptor de TSH (TSHR), função patogenética na DT. Até o momento não foi descrita anormalidade no gene TITF1 como causa de HC, enquanto foram identificadas mutações no PAX-8 em cinco recém-nascidos com DT. Embora não envolvidas na DT, mutações inativadoras do TSHR podem produzir espectro de defeitos congênitos oscilando entre hipertirotropinemia com eutireoidismo e hipotireoidismo com hipoplasia glandular. A clonagem dos genes envolvidos na biossíntese dos hormônios tireóideos, como o da tireoperoxidase (TPO) e tireoglobulina (Tg), permitiu a identificação de mutações responsáveis por alguns casos de bócio e hipotireoidismo decorrente de defeito de incorporação de iodeto ou anormalidades na síntese de Tg. Recentemente, foi demonstrada a base molecular do defeito de transporte ativo de iodeto e da síndrome de Pendred, respectivamente, devidas a mutações no gene NIS (simportador de sódio e iodeto) e no gene PDS (pendrina). em conclusão, grande parte dos pacientes com HC e DT não tem esclarecida, ainda, a causa molecular desta síndrome.

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The purpose of this study was to estimate the repeatability of transferable embryos in Holstein cows and to evaluate the effects of the year, season and order of the superovulation on the number of total structures, transferable embryos, non-transferable embryos and ovules. Four hundred and eighty-six superovulations were used in the analysis. The year of superovulation affected significantly all traits (P<0.01); however, we did not find effects of the season of the year. Superovulation order affected the total structures (P<0.01) and non-transferable embryos (P<0.05). The repeatability of the transferable embryo was 0.28 +/- 0.05. Positive correlations were found among total structures and transferable embryos (0.73) and total structure and ovule (0.51).

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The pattern of change in shape during postnatal development in skulls of punare (Thrichomys apereoides) skulls, was studied by geometric morphometric techniques. Skull shape observed in T. apereoides varied both with size and age, but variation in size explains most of the overall change in shape. Differences in shape observed among the eight age categories showed that main changes in shape occurred principally between the first and second age categories. Among the other age classes, changes became less pronounced leading to elongation of the snout and the mid-face and narrowing of the basicranium. The change in global shape resulted in lateral compression of the skull. Despite the high level of integration observed, localized transformations dominated the ontogenetic changes in shape indicating the presence of two large scale cranium components-the orofacial and the basicranial region. The ontogenetic pattern in this species seems to follow the same trends observed in the initial phases of development.

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The scaling of oxygen uptake was measured along the ontogeny, in the neotropical pitviper Bothrops moojeni. Allometric relationship between oxygen uptake and body mass, quantified for juveniles, sub-adults and adults, showed the same mass coefficient and exponent. The uniformity of mass constants along ontogeny suggests that B. moojeni is energetically homomorphic. Variation in mass seem to be the sole determinant of oxygen uptake, and structural modifications have no effect on the metabolic rate. Applications of the homomorphism principle to assess variations in mass coefficient and exponent for intraspecific analysis of metabolism in reptiles are discussed. B. moojeni had an oxygen consumption in the range reported for viperids, but lower than that for colubrid snakes of similar size. Possible causative reasons for this pattern is discussed.

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The Pleistocene Chui Formation at Osorio (Rio Grande do Sul, Brazil) consists of coastal marine and eolian sands, the former containing abundant and well-preserved Ophiomorpha nodosa burrow systems. Detailed ichnological study has revealed interesting features associated with them. Small-sized Ophiomorpha, here assigned to a new ichnospecies, O. puerilis, are interpreted as possible burrows of juvenile thalassinidean crustaceans probably belonging to the same species as the producers of larger O. nodosa. Additionally, helicoidal burrows with thick, concentrically laminated linings are associated with the walls of O. nodosa. They are assigned to the new ichnospecies Cylindrichnus helix, and they are interpreted as dwellings of commensal annelid worms. The association of these three icbnospecies constitutes a fossil example of the role of thalassinideans as ecosystem engineers able to modify their environment and to create new space and resources usable by other organisms. (c) 2005 Elsevier B.V. All rights reserved.

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is a predominant characteristic, conditioned by the presence of castes with different morphology, ontogeny, and development. The soldier caste is unique among social insects and it is responsible for colony defense. Soldiers belonging to the Nasutitermitinae subfamily are very peculiar, since they may be polymorphic and present a nasus in addition to either developed or vestigial mandibles. The defensive secretions of soldiers of the neotropical Nasutitermitinae have been the aim of several chemical studies, but few data exist concerning the anatomy and histology of the exocrine glands. This article presents a comparative study on the anatomy of the frontal gland of soldiers of several Nasutitermitinae species: Syntermes dirus (Burmeister), Syntermes nanus (Constantino), Constrictotermes cyphergaster (Silvestri), Nasutitermes corniger (Motschulsky) and Velocitermes heteropterus (Silvestri), with emphasis on the ultramorphology and ultrastructure of the frontal tube.

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Four. male Wistar rats were housed in pairs of siblings, on LD 12:12h and 22 degrees C + 2 degrees C. Food and water were provided ad libitum. Behavior was videotaped from the 1st to the 3rd month of life. In each age-bracket the spectral composition of rhythmic expressions of the following behavioral categories was analyzed: rest, eat, drink, cage exploration, self-grooming, and social interaction. Rats maintained a stable rank order of time engaged in different behaviors through development, despite modification of time spent in grooming, drinking and social interaction as they got older. Spectral composition of behaviors followed a general ontogenetic pattern: ultradian frequencies of 12-h and 8-h were the strongest in the 1st month and circadian periodicity was predominant in the 3rd month. The increase of circadian power compared with ultradian power components agrees with literature findings. To our knowledge, self-grooming and social interaction have not been investigated before in this context. The similarities between siblings suggest the mutual influence of partners and/ or the existence of genetic factors. Ongoing studies are examining the importance of the social surroundings in which animals develop to the acquisition of adult rhythmic pattern.

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The embryology and seed structure of Paepalanthus sect. Actinocephalus species were studied. The embryological and structural seed characters fit well with those of the other commelinaceous families. Within the Commelinales sensu Dahlgren, Eriocaulaceae and Xyridaceae represent two embryologically close families. In Paepalanthus sect. Actinocephalus the ovule is orthotropus, bitegmic, and tenuicellate with a micropyle formed by the inner integument. The seeds are endotestal. The outer cell layer of the testa and the outer periclinal wall of the endotesta disintegrate during development. The endotegmen is tanniniferous. The outer layer of the tegmen becomes compressed and is no longer recognizable in the mature seed. The seeds are operculate.