Full-text resources of PSJD and other databases are now available in the new Library of Science.
Visit https://bibliotekanauki.pl
Preferences help
Polish version English version Language
enabled [disable] Abstract
Number of results

Results found: 3

Number of results on page
first rewind previous Page / 1 next fast forward last

Search results

help Sort By:

help Limit search:
first rewind previous Page / 1 next fast forward last
1

Intercellular cytoplasm transport during oogenesis of the moth midge, Tinearia alternata Say (Diptera: Psychodidae)

100%
Mazurkiewicz M., Kubrakiewicz J.
Folia Biologica
|
2001
|
vol. 49
|
issue 3-4
205-213
EN
Polytrophic ovaries of the nematocerous dipteran, Tinearia alternata Say consists of several developmentally synchronized ovarioles each housing only one functional egg chamber with 15 nurse cells and an oocyte. At the early stages of previtellogenesis the nurse cells become polyploid and synthetically active. Their nuclei contain polytene chromosomes and prominent nucleoli. With the advance of previtellogenic growth the nurse cell cytoplasm is loaded with the growing number of ribosomes and contain perinuclear nuage material, mitochondria, electron dense bodies and aggregations of endoplasmic reticulum. All these organelles are transported into the oocyte thanks to the massive and rapid flow of the nurse cell cytoplasmic contents. Nurse cell?oocyte transport is mediated by actin cytoskeleton. Prior to the rapid cytoplasm transfer, F-actin network is associated with the nurse cell membranes while tiny bundles of microfilaments form actin baskets connected with ring canals. Nurse cells in Tinearia lack an extensive scaffold of radially oriented, F-actin bundles (cables) that would tether their nuclei in place, thus preventing ring canals from plugging. The way the nuclei are anchored to their central positions within the cells remains unclear. Towards the final stages of oogenesis nurse cells are almost devoid of cytoplasm and degenerate. Although their nuclei undergo dramatic morphological transformations, typical hallmarks of apoptotic pathway could not be clearly observed. Rapid ooplasmic streaming does not occur.
2

Ovariole development in telotrophic ovaries of snake flies (Raphidioptera)

100%
Jedrzejowska I., Kubrakiewicz J.
Folia Biologica
|
2004
|
vol. 52
|
issue 3-4
175-184
EN
Snake flies (Raphidioptera), alder flies (Megaloptera: Sialidae) and also some myxophagan coleopterans share the same, peculiar telotrophic organization of their ovarioles usually referred to as ovarioles of the Sialis-type. Ovariole ontogenesis in Raphidia sp. is described and the basic events that lead to the formation of germ cell clusters and their subsequent transformations are reported. It was found that the major cellular events during ovariole formation in Raphidia and Sialis are essentially the same. Discrepancies concern details of germ cell cluster formation, differentiation of cystocytes within clusters and their location within the developing tropharium. Based on these results the hypothetical model of the Sialis-type ovariole formation, previously presented by KING and BNING (1985) is verified. A hypothesis on the mechanisms of oocyte determination in telotrophic ovaries is also presented.
3

Structure of ovaries and oogenesis in Corydalidae and Chauliodidae (Insecta, Megaloptera). I. Architecture of adult ovarioles and previtellogenesis

81%
Szymanska B., Kubrakiewicz J., Jankowska W., Bilinski S. M.
Folia Biologica
|
2001
|
vol. 49
|
issue 1-2
91-97
EN
The results of histological and EM studies on the ovaries of three representatives of Megaloptera: Chauliodes pectinicornis, Nigronia fasciata (Chauliodidae), and Corydalus peruvianus Corydalidae) are presented. It is shown that the ovaries of all 3 investigated species are panoistic (secondary panoistic, = neopanoistic) and consist of numerous (more than a hundred) ovarioles that are differentiated into 3 well-defined regions: the terminal filament, the germarium, and the vitellarium. The germaria of adult females are apparently non-functional and contain germ and somatic cells in various stages of degeneration. The vitellaria are composed of 12 ? 15 developing ovarian follicles (= oocytes surrounded by follicular cells) in a linear arrangement. In adult females these follicles can be classified into early previtellogenic, late previtellogenic, vitellogenic, and choriogenic. During early previtellogenesis oocyte nuclei (= germinal vesicles) contain single nucleolar masses. Histochemical analyses indicate that within the masses DNA as well as AgNOR proteins are present. During subsequent stages of the previtellogenic growth nucleolar masses gradually break down into smaller aggregations of coarse granular material, i.e. multiple nucleoli. In chauliodids the nucleoli are distributed evenly throughout the nucleoplasm while in the corydalid, C. peruvianus, they form a characteristic ring. The presented results are discussed in a phylogenetic context.
first rewind previous Page / 1 next fast forward last
JavaScript is turned off in your web browser. Turn it on to take full advantage of this site, then refresh the page.