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Biomedical subjects

W Witaliński

Publications and source records attributed to W Witaliński.

11 recordsLinked to original sources
PubMed1994

Actin in spermatozoon of a soft tick, Argas (A.) polonicus (Ixodida, Acari).

Distribution of actin in spermatozoa before (prospermia) and after (spermiophores) cell eversion process in a soft tick, Argas (A.) polonicus, was studied by phalloidin-rhodamine fluorescence and immunogold labelling methods. F-actin was mainly localized at the cortical cytoplasm surrounding the vacuole in prospermia and along the periphery of spermiophores. A further localization of actin was in the cytoplasm in the "head" and adjacent region both in prospermium and spermiophore. Immunogold labelling revealed the presence of actin in the cytoplasm of whole spermatozoon with higher concentration in the "head" region. In the peripheral cytoplasm, however, actin was found in the material coating electron-dense fibres. The fibres themselves and cell protrusions were not labelled suggesting that F-actin was localized around dense fibres. Of two distinct pools of F-actin found in the tick spermatozoa, the one located in the subplasmalemmal cytoplasm is supposedly responsible for the gliding movement, whereas that filling the anterior tapered end including "head"--may be involved in contortional movements of that region. The participation of actin-based mechanism in forward gliding of spermiophores was confirmed in experiments with cytochalasin B. The contribution of actin to prospermium vacuole opening and subsequent cell eversion is suggested.

Actins↗
PubMed1990

Anatomy and ultrastructure of the reproductive systems of Acarus siro (Acari: Acaridae).

Anatomy and ultrastructure of the female and male reproductive system in Acarus siro L. were investigated by light and electron microscopy. The female system consists of paired ovaries of nutrimentary type in which oogonia and oocytes are connected by bridges with a large central cell. The oviducts empty into the uterus, which passes into preoviporal duct lined by cuticle, and opening as a longitudinal slit (oviporus). An elongated accessory gland composed of one type of secretory cell is located along each oviduct. The copulatory opening occurs at the posterior margin of the body and leads, via the inseminatory canal, to the receptaculum seminis, consisting of the basal and saccular part. Both inseminatory canal and basal part of receptaculum seminis are lined by cuticle, whereas the wall of the sac is formed by cells covered only by long, numerous microvilli. The basal part of the receptaculum seminis joins the ovaries via two lumenless transitory cones. The male reproductive system contains paired testes, in which spermatogonia tightly surround the central cell. The proximal part of the paired vasa deferentia serves as a sperm reservoir, while the distal one has a glandular character. An unpaired, cuticle-lined ejaculatory duct opens into the apex of the aedeagus. The single accessory gland is located asymmetrically at the level of, or slightly posterior to, coxae IV. The structure of the genital papillae, which are topographically related to the genital opening in both sexes, is also briefly described.

Animals↗
PubMed1982

Unusual structural changes in mitochondria during spermiogenesis in the oribatid mite, Hafenrefferia gilvipes (Acari).

During spermiogenesis in the oribatid mite, Hafenrefferia gilvipes, striking alterations in the structure and location of mitochondria in spermatids were observed. The structural changes include formation of a single, distended annular crista, which subsequently becomes tubular. Initially, the mitochondria are located in central regions of the cytoplasm, they then move first to the plasmalemma and subsequently to the nuclear envelope, and finally are engulfed in the nuclear material.

Animals↗
PubMed1982

Extraocular muscles in the lamprey, Lampetra fluviatilis L. I. Muscle fibres.

Six extraocular muscles of the river lamprey, Lampetra fluviatilis L., were studied with the light and electron microscope. On the basis of morphology and histochemistry three types of muscle fibres were distinguished: thin, thick mitochondria-rich and thick multifibrillar fibres. In the thin fibres, 2.8-22.4 microns in diameter, myofibrils are distributed peripherally and show strong ATPase activity. The mitochondria are located paraxially. In the thick mitochondria-rich fibres, 19.4-31.0 microns in diameter, myofibrils are also located peripherally, whereas the central part of the fibre is densely packed with very numerous mitochondria possessing tubular cristae. Thick multifibrillar fibres, with a diameter similar to that of the former type, contain thin myofibrils scattered over the entire cross-section of the fibre. The activity of myofibrillar ATPase is lower in both types of thick fibres than in the thin ones. The tubules of the T system were observed frequently only in the thick multifibrillar fibres. The extraocular muscles of the lamprey are composed of large quantities of muscle fibres. Thin and thick fibres do not form separate layers, but are more or less uniformly distributed throughout the muscle. Many muscle fibres show structural features suggesting their degeneration.

Adenosine Triphosphatases↗
PubMed1976

Spermatogenesis in free living mite, Pergamasus viator Halaŝ. (Parasitidae, Mesostigmata). II. Spermiogenesis.

The paper presents the results of ultrastructural studies on the spermiogenesis in the mite, Pergamasus viator Halaŝkova. The cysts containing 16 spermatids per cyst, are localized in the anterior part of the saccular gonad. The process of spermatid maturation has been divided into three stages: of the early spermatid, middle spermatid and late spermatid. The modifications of spermatid occuring during the spermiogenesis include: a change of cell shape, modifications of its organelles and formation of new structures like the superficial layer of cellular processes, striated bodies, granular bodies, flattened cisternae and canaliculi, central canaliculi, and stiff bands. Within the nucleus the chromatin condenses to threads or lamellae, to form subsequently several electron-dense granules. The remaining nucleoplasm is filled with an electron-dense material, which appears in the middle spermatid and gradually accumulates. The above modifications occuring in the course of spermiogenesis and their relation to the data available from the literature concerning the spermatogenesis of allied groups of animals are discussed in length.

Animals↗
PubMed1975

Structure of muscle fibres and motor end plates in extraocular muscles of the grass snake, Natrix natrix L.

Six extraocular muscles of the grass snake, Natrix natrix L. together with their motor end plates were examined in the light and electron microscope, and the measurements of the diameter of muscle fibres and the area of their motor end plates were performed. Morphologically, two types of muscle fibres: tonic and red phase ones were distinguished. The former fibres, 2,3 to 14,5 mum in diameter possess single or multiple (up to five on a single fibre) "en grappe" motor end plates, without postsynaptic junctional folds. The latter fibres, 10...40 mum in diameter have single, "en plaque" motor end plates, with numerous postsynaptic junctional infoldings. The morphological features of muscle fibres and motor end plates as well as the correlation between the diameter of muscle fibres and the area of motor end plates are discussed.

Animals↗