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1
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The ultrastructure and cytochemistry of Mehlis' gland and egg-shell formation in Schistosoma haematobium

100%
Swiderski Z., Moczon T., Eklu-Natey D. T.
Wiadomości Parazytologiczne
|
1998
|
tom 44
|
nr 3
2
Artykuł dostępny w postaci pełnego tekstu - kliknij by otworzyć plik
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Schistosoma japonicum: the chemical nature of the secretion produced by the Mehlis' gland

100%
Moczon T., Swiderski Z.
Wiadomości Parazytologiczne
|
1998
|
tom 44
|
nr 3
3

Ultrastructure of the intrauterine eggs of Didymobothrium rudolphii [Monticelli, 1890] [Cestoda, Spathebothriidea, Acrobothriidae] and its phylogenetic implications

84%
Swiderski Z., Gibson D. I., Santos M. J., Poddubnaya L. G.
Acta Parasitologica
|
2010
|
tom 55
|
nr 3
254-269
The intrauterine polylecithal eggs of the spathebothriidean cestode Didymobothrium rudolphii (Monticelli, 1890) were examined by means of transmission electron microscopy (TEM). Each unembryonated egg is composed of a fertilised oocyte or ovum and several vitelline cells, all surrounded by a newly formed shell. The lumen of the proximal uterus is packed with unutilised vitelline material and eggs at different stages of shell formation. In the proximal region of the uterus, the fertilised oocytes, initially surrounded by dense, discontinuous islands of eggshell material and containing long axonemes of spermatozoa in their cytoplasm, were frequently observed. Sperm axonemes also remain in the oocyte cytoplasm of eggs surrounded by a thick electron-dense shell until the sperm nucleus is transformed into a male pronucleus. Despite the fact that the two-pronuclei stage and cell divisions within the eggs of D. rudolphii were never observed, individual eggs containing several blastomeres of different sizes were seen in the middle and distal regions of the uterus. This provides indirect evidence that at least a few initial cleavage divisions must take place in the intrauterine eggs and direct evidence that the early embryonic development of D. rudolphii starts in utero. The several vitellocytes present in each egg contain nutritive reserves for the developing embryos; these are composed mainly of numerous lipid droplets and a moderate amount of glycogen. In the eggs containing early embryos composed of several blastomeres, the cytoplasm of the degenerating vitellocytes exhibits the presence of so-called ‘foci of cytoplasmic degradation’, which appear to be involved in the autolytic process of the vitellocyte cell components and inclusions, such as a high accumulation of lipids and glycogen. This progressive degeneration of the vitellocytes, considered as an example of programmed cell death or apoptosis, likely contributes towards the resorption of nutritive reserves by the developing embryo. Some of the results of this study are commented upon in relation to the affiliation of the spathebothriideans with other lower cestode groups.
4

Fine structure of egg-forming complex ducts, eggshell formation and supporting neuronal plexus in progenetic Diplocotyle olrikii [Cestoda, Spathebothriidea]

84%
Poddubnaya L. G., Mackiewicz J. S., Swiderski Z., Brunanska M., Scholz T.
Acta Parasitologica
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2005
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tom 50
|
nr 4
Ultrastructural descriptions of the oviduct, fertilization canal, seminal receptacle, ovovitelline duct, vitelline reservoir, ootype, Mehlis' gland, proximal uterus, and neurosecretory elements associated with egg-forming ducts are given for the progenetic spathebothriidean tapeworm, Diplocotyle olrikii from the body cavity of Gammarus oceanicus. The functional significance of cortical granules of the oocyte, as necessary elements for joining vitelline material to an oocyte in the ovovitelline duct, is established. The proximal ootype has a vesicular epithelium and is the site of initial, nascent eggshell formation. Precursors of nascent eggshell are vesicles, synthesized in both the proximal ootype wall and vitelline cytoplasm that become associated with the newly formed shell. Major shell structure comes from subsequent deposition of shell globules from a disintegration of vitelline clusters. Mehlis' gland has a single secretory cell type. Secretory granules from Mehlis' gland become associated with the developing egg that passes through to the distal ootype and proximal uterus where egg-formation is completed. It is not known, however, whether Mehlis' gland secretion promotes breakdown of free vitelline cells, liberation of shell globules, confluence of shell globules on the developing eggshell or provides further structural components for the shell. Despite some differences in ootype morphology, the basic process of eggshell formation in D. olrikii may share much in common with the Pseudophyllidea and Caryophyllidea. Small vesicles and dense-core vesicles are in nerve terminals near duct musculature. Nerve terminals with large dense vesicles are described near, in, and within the seminal receptacle, fertilization canal and distal ootype. The possible physiological effects of exocrine neurosecretions are discussed.
5

Zmiany stezenia estradiolu i progesteronu w plynie macicznym kury podczas tworzenia skorupy jaja

67%
Rzasa J., Mika M.
Acta Agraria et Silvestria. Series Zootechnica
|
1995
|
tom 33
97-101
6

Diversification of the follicular cells in the panoistic ovary of the stone fly Perlodes intricata [Pictet, 1841] [Plecoptera: Perlodidae] during choriogenesis

67%
Rosciszewska E.
Zoologica Poloniae
|
1996
|
tom 41
|
nr 1-4
7

Zmiany stezenia sodu, potasu, chloru i glukozy w plynie macicznym kury podczas tworzenia skorupy jaja

51%
Sobstel P., Rzasa J., Luszczynski J.
Acta Agraria et Silvestria. Series Zootechnica
|
1993
|
tom 31
89-98
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