Biomedical subjects

Z Swiderski

Publications and source records attributed to Z Swiderski.

At least 19 recordsLinked to original sources

PubMed1997

Ultrastructure of oncospheral hook formation in the nematotaeniid cestode, Nematotaenia dispar (Goeze, 1782).

Ultrastructural characteristics of oncospheral hook morphogenesis in the nematotaeniid cestode, Nematotaenia dispar, are described. The primordia of embryonic hooks appear in the advanced phase of the pre-oncosphere in 6 specialised hook-forming cells or oncoblasts. Each hook primordium, situated near an invaginated part of the nucleus, is surrounded by numerous free ribosomes, mitochondria and extended Golgi regions. Simultaneously with the hook primordium elongation and transformation into a blade, handle and base, the hook material differentiates into an electron-dense cortex and a less dense, inner, crystal-like core. The exit of the blade of the mature hook, protruding from the oncosphere, is surrounded by a circular, septate desmosome and 2 rigid, dense rings on either side. The pattern of oncospheral hook morphogenesis in N. dispar is compared with that of 2 previously examined cyclophyllidean cestodes, Inermicapsifer madagascariensis and Catenotaenia pusilla.

Animals↗

PubMed1997

Differentiation and ultrastructure of the paruterine organs and paruterine capsules, in the nematotaeniid cestode Nematotaenia dispar (Goeze, 1782) Lühe, 1910, a parasite of amphibians.

Three types of egg-protecting envelopes of parenchymatic, uterine and embryonic origin have been distinguished in the cyclophyllidean cestode Nematotaenia dispar (Goeze, 1782) Lühe, 1910, a type species for the genus Nematotaenia and the family Nematotaeniidae. The present paper deals with the parenchymatic envelopes, which originate from the modified medullary parenchyma and are represented in this species by the paruterine organs and paruterine capsules. In pregravid proglottids they are composed of clongated myocytons, myofibrils and membranous anucleate cellular processes, containing a large amount of lipid droplets and some calcareous corpuscle cells. These cellular elements (CE) are separated from each other by abundant extracellular matrix (ECM), which consists primarily of an electron lucent ground substance with fine filaments embedded in it. The paruterine capsules of gravid proglottids are surrounded from the outside by a typical medullary parenchyma and are lined by a layer of the connective tissue. The paruterine organs and paruterine capsules show similar ultrastructure. During their histogenesis, all cellular elements undergo extensive flattening, followed by cellular deterioration, with simultaneous reduction in CE/ECM ratio. In the late gravid segments, paruterine capsule walls are very thick and consist of membranous sheets with large amounts of lipid droplets, which cause the cytoplasmic sheets to bulge. Ultrastructure of various types of parenchymatic envelopes in representatives of different cyclophyllidean families, such as paruterine organs in Nematotaeniidae and Mesocestoididae, uterine and parenchymatic egg capsules in Anoplocephalidae (Linstowiinae and Inermicapsiferinae, respectively), is compared.

Animals↗

PubMed1997

Differentiation and ultrastructure of oncospheral and uterine envelopes in the nematotaeniid cestode, Nematotaenia dispar (Goeze, 1782).

The oncospheral envelopes of infective eggs in Nematotaenia dispar include the outer envelope with 2 sublayers, the inner envelope with a fibrillar embryophore and 2 cytoplasmic sublayers, and the oncospheral membrane. They differentiate from 3 primary embryonic envelopes, capsule, outer and inner envelope. The uterine envelopes are formed around the early embryos by processes of uterine epithelial cells, which surround the capsules. They degenerate rapidly in later stages; however, some structural components of the uterine envelopes were still visible in gravid proglottids as flattened perikarya with pyknotic, lobate nuclei, residual membranous structures and cellular debris situated usually between eggs. The following ultrastructural features of oncospheral envelopes differentiation appear to be characteristic for N. dispar: (1) lack of the outer capsule or shell in the fully mature eggs; (2) bi-layered structure of the outer envelope and tri-layered structure of the inner envelope; (3) absence of hook region membrane resulting probably from its early disintegration; (4) presence of small vesicles or "pits" incorporated into the inner envelope plasma membrane; (5) presence of densely packed microtubules in the external layer of the inner envelope; (6) changes in number of mitochondria and free ribosomes in the external and internal layers of inner envelope during egg maturation; and (7) probable "passage" of mitochondria and free ribosomes through the embryophoral pores in the developing eggs.

Amphibians↗

PubMed1996

[Comparative studies on the ultrastructure, homology and analogy of egg envelopes in trematodes and cestodes].

The origin, differentiation and functional ultrastructure of egg envelopes surrounding developing and mature miracidia of Schistosoma mansoni and that of developing and mature coracidia of Bothriocephalus clavibothrium have been examined by means of electron microscopy and cytochemistry. Results obtained on these two species were compared with data from our previous studies on the ultrastructure of egg envelopes in different cyclophyllidean (Hymenolepididae, Taeniidae, Anoplocephalidae, Davaineidae) and proteocephalidean cestodes. In the mature infective egg, the three main egg envelopes (the egg-shell, and the outer and inner envelope) that surround the larvae (miracidia of Digenea, coracidia of Pseudophyllidea, and hexacanths of Cyclophyllidea and Proteocephalidea), show evident similarities in their origin, functional ultrastructure and chemical composition. Conclusions of this comparison, concerning analogy and homology in egg envelopes of trematodes and cestodes, are drawn and discussed.

Animals↗

PubMed1995

Transmission electron microscope studies on the oncospheral envelopes of Taenia saginata after niclosamide treatment.

The gravid proglottids of Taenia saginata from human infection before and after treatment of patient with niclosamide (Yomesan) were used for studies on oncosphere envelope ultrastucture. The envelopes examined were intact after drug treatment. The samples from niclosamide-treated and untreated patients were similar with respect to number and kinds of the protective structures surrounding the oncospheres inside gravid proglottids. Their morphology was generally similar to this described earlier for other taeniid species. Details of the ultrastructure of oncospheral envelopes from niclosamide-treated patients are presented in the paper. Contamination of the environment with eggs from treated patients, particularly in poor sanitary conditions, is discussed.

Animals↗

PubMed1992

Schistosoma haematobium: histochemistry of glycogen, glycogen phosphorylase a and glycogen branching enzyme in niridazole-treated females.

The body posterior to the ovary of Schistosoma haematobium females was investigated. Glycogen, glycogen phosphorylase a (EC 2.4.1.1) and glycogen branching enzyme (EC 2.4.1.18) activities were detected in the subtegumental muscle system, parenchyma and mature vitelline cells, whereas no activities were detected in the tegument and immature vitelline cells of the parasite. Administration of a single niridazole dose of 250 mg kg-1 to the pouched mouse (Saccostomus camestris) produced the following changes in S. haematobium females: a relatively rapid depletion of glycogen stores due to disruption of the absorptive surface of the parasite, and to an increase in the activity of glycogen phosphorylase a; a reduction in the phosphorylase a to phosphorylase b-conversion capacity of glycogen phosphorylase phosphatase (EC 3.1.3.17); a decrease in glycogen branching enzyme activity; and a relatively rapid degeneration of parasite cells possibly due to their loss of endogenous energy reserves.

1,4-alpha-Glucan Branching Enzyme↗

PubMed1992

Schistosoma mansoni: the chemical nature of the secretions produced by the Mehlis' gland and ootype as revealed by cytochemical studies.

The 'secretory pathway' of the Mehlis' gland secretion as well as the maturation of the secretory granules are described. The secretions produced by the Mehlis' gland and the distal ootype in Schistosoma mansoni were identified as neutral glycoproteins. They were both periodate reactive, stained with phosphotungstic acid at low pH, and sensitive to the proteolytic action of papain. The secretions did not strain with both the low-iron diamine and the high-iron diamine methods for the presence of acidic glycoconjugates, and they did not contain a detectable level of sulphydryl groups. The possible role of the secretion from the Mehlis' gland in egg-shell formation is discussed.

Animals↗

PubMed1992

Fine structure of spermiogenesis in the coccid insect Aspidiotus perniciosus: late stages of differentiation and structure of the mature sperm bundles.

Spermatids of A. perniciousus are organized into bundles each containing 32 cells. During the process of differentiation, nuclear elongation and chromatin condensation take place. The mature sperm bundles are finally surrounded by the secondary sheath which is composed of a trilaminar membrane. The mature sperm is not differentiated into head, mid piece or tail but has two tapering ends and an electron dense central core. Centrioles, the nuclear membrane, mitochondria and a flagellum appear to be lacking. Microtubules are arranged in a spiral pattern forming the enveloping microtubular sheath.

Animals↗

PubMed1992

A freeze etching study on the distribution of nuclear pores during spermatogenesis in ticks.

In this study the freeze-fracturing and freeze-etching techniques was used to study pore distribution during spermatogenesis in ticks. Three species of Ixodid ticks were studied: Hyalomma dromedarii, H. marginatum and Amblyomma hebraeum. In all three species of the ticks examined, the nuclei of the early stages of male germ cells showed varying degrees of aggregation into pore-rich and pore-poor areas. Spermatocytes demonstrated significant pore clustering in pore-rich areas, leaving areas almost devoid of pores. Spermatids on the other hand displayed a random distribution of nuclear pores. This random distribution was soon modified in the course of nuclear differentiation. Nuclear pores disappeared in the nuclei of mature spermatozoa of the ticks examined.

Animals↗

PubMed1986