Desenvolvimento nuclear de celulas troficas ovarianas de Chrysomys putoria (Diptera, Calliphoridae)

AUTOR(ES)
DATA DE PUBLICAÇÃO

1988

RESUMO

The nuclei of proximal nurse cells of the ovary of Chrysomya putoria in the different stages of ovarian development were examined in preparations submitted to the Feulgen reaction. The objective was to follow the chromatin/chromosomal alterations occurring during the development of those cells involved in the process of egg formation. The most marked alteration encountered was the organizatian of the chromatin in the form of typical polytene chromosomes. In this stage 6 chromosomes could be seen, in which, at a specific point in their process of compactation, the pattern of bands and interbands characteristic of dipteran polytene chromosomes, could be seen. After this stage the chromosomes became increasingly shorter until, when all were practically the same length, their constituent filaments began to separate and scatter throughout the nuclear space. From this point on, up to the end of development, the nucleus exhibited an interphasic appearance, presenting one strongly staining heterochromatic body. The euchromatic region of the X chromosome underwent premature decompactation as compared to the autosomes and to its own heterochromatic segment. If the adult female were maintained on a sugar and water diet, the polytene chromosomes would remain as such for a much longer period than when maintained on a standard diet. Microspectrophotometry showed that the nuclei became highly endopolyploidy during oogenesis, attaining a maximum value of 2048 C, resulting from 10 cycles of DNA duplication. At each stage, lower values were found in the distal nuclei, showing the existence of asynchrony in the endoreplicative cycles of the different nurse cells of the follicle. The volume occupied by the stained chromatin increased 12 or 15 times during development. Neither this Feulgen-DNA values nor the area occupied by the heterochromatic body proportionally followed the growth of the rest of the chromatin. The epithelial cells of the follicle also showed endopolyploidization, passing through up to 4 cycles of replication after the start of vitellogenesis

ASSUNTO(S)

inseto - ovo - implantação mosca - controle - celulas oogenese mosca - ovos - desenvolvimento

ACESSO AO ARTIGO

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