The tylenchid (Nematoda) egg shell: formation of the egg shell in Meloidogyne javanica

Oogonia of Meloidogyne javanica are radially arranged around a central rachis to which they are attached by cytoplasmic bridges. As the oocytes mature the rachis disappears and the oocytes pass through the oviduct in tandem. The oviduct-spermatotheca valve is constructed of two rows of tightly packed cells of which there are four per row. The nuclei of these cells are large and contain balloon-shaped cytoplasmic invaginations. The spermatotheca is characterized by microtubules which extend to its lumen and by invaginations of plasmalemma. Cells of the distal uterine region contain large intracytoplasmic spaces bordered by endoplasmic reticulum whereas proximal uterine cells have dense cytoplasm and large areas of compact endoplasmic reticulum. Egg-shell formation begins in the spermatotheca with the modification of the oolemma to form the vitelline layer. The chitinous layer begins in the distal portion of the uterus and appears to originate from the egg. Proline-containing protein is incorporated into the chitinous and lipid layers as the egg passes through the mid-region of the uterus and formation of the lipid layer in this region completes egg development.

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The tylenchid (Nematoda) egg shell: formation of the egg shell in Meloidogyne javanica

Parasitology ◽

10.1017/s003118200004316x ◽

1976 ◽

Vol 72 (1) ◽

pp. 29-39 ◽

Cited By ~ 19

Author(s):

Michael A. McClure ◽

A. F. Bird

Keyword(s):

Endoplasmic Reticulum ◽

Meloidogyne Javanica ◽

Distal Portion ◽

Shell Formation ◽

Lipid Layer ◽

Dense Cytoplasm ◽

Cytoplasmic Bridges ◽

Pass Through ◽

Egg Shell ◽

Lipid Layers

SummaryOogonia of Meloidogyne javanica are radially arranged around a central rachis to which they are attached by cytoplasmic bridges. As the oocytes mature the rachis disappears and the oocytes pass through the oviduct in tandem. The oviduct-spermatotheca valve is constructed of two rows of tightly packed cells of which there are four per row. The nuclei of these cells are large and contain balloon-shaped cytoplasmic invaginations. The spermatotheca is characterized by microtubules which extend to its lumen and by invaginations of plasmalemma. Cells of the distal uterine region contain large intracytoplasmic spaces bordered by endoplasmic reticulum whereas proximal uterine cells have dense cytoplasm and large areas of compact endoplasmic reticulum. Egg-shell formation begins in the spermatotheca with the modification of the oolemma to form the vitelline layer. The chitinous layer begins in the distal portion of the uterus and appears to originate from the egg. Proline-containing protein is incorporated into the chitinous and lipid layers as the egg passes through the mid-region of the uterus and formation of the lipid layer in this region completes egg development.

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Oogenesis and egg-shell formation in Aspiculuris tetraptera Schulz (Nematoda: Oxyuroidea)

Parasitology ◽

10.1017/s0031182000049192 ◽

1979 ◽

Vol 78 (2) ◽

pp. 131-143 ◽

Cited By ~ 18

Author(s):

D. A. Wharton

Keyword(s):

Vitelline Membrane ◽

Shell Formation ◽

Perivitelline Space ◽

Lipid Layer ◽

Cytoplasmic Inclusions ◽

Inner Surface ◽

Egg Shell ◽

Aspiculuris Tetraptera ◽

Lipid Layers

SUMMARYThe ovary of Aspiculuris tetraptera has a prominent terminal cap cell. This is considered to be part of the ovarian epithelium. Oogonia detach from the short rachis and increase in size from 6 to 60 μm; accumulating hyaline granules, shell granules and glycogen. The hyaline granules persist in the egg cytoplasm after shell formation has been completed and are considered to be lipoprotein yolk. The shell granules contribute to the non-chitin fraction of the chitinous layer. A classification of the cytoplasmic inclusions of the nematode oocyte is proposed. Upon fertilization a vitelline membrane is formed which constitutes the vitelline layer of the egg-shell. The chitinous layer is secreted in the perivitelline space, between the vitelline layer and the egg oolemma. Upon completion of chitinous layer synthesis, the egg cytoplasm contracts away from its inner surface. The material of the lipid layer is secreted at the surface of the egg cytoplasm and adheres to the inner surface of the chitinous layer. During secretion of the chitinous and lipid layers by the egg cytoplasm, the uterine cells secrete the unit membrane-like external uterine layer and the crystalline internal uterine layer. A complex system of interconnecting spaces develops in the internal uterine layer. This system is open to the exterior via breaks in the external uterine layer. There is no direct involvement of the uterine cells in the formation of this structure.

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The tylenchid (Nematoda) egg shell: structure, composition and permeability

Parasitology ◽

10.1017/s0031182000043158 ◽

1976 ◽

Vol 72 (1) ◽

pp. 19-28 ◽

Cited By ~ 79

Author(s):

Alan F. Bird ◽

M. A. McClure

Keyword(s):

Basic Structure ◽

Vitelline Membrane ◽

Chemical Components ◽

Rotylenchulus Reniformis ◽

Lipid Layer ◽

Tylenchulus Semipenetrans ◽

Different Temperatures ◽

Egg Shells ◽

Egg Shell ◽

Lipid Layers

SummaryThe fine structure of egg shells of four different genera belonging to the order Tylenchida has been examined. The species examined were Meloidogyne javanica, Rotylenchulus reniformis, Tylenchulus semipenetrans and Pratylenchus minyus. They are all similar in their basic structure, being composed of vitelline membrane, chitin and lipid layers, but there is considerable variability in the thickness of these layers.We have retained the conventional nomenclature because of its convenience, but it is clear that these layers have a variety of chemical components. However, they do appear to contain the compounds from which they take their name. Thus chitin occurs in the chitin layer, and lipid in the lipid layer. The latter is removed by the technique used in isolating the shell from the egg. Chemical analysis of the hydrolysis products of these shells has revealed a high (35 %) proline content which appears to be a characteristic of those nematode egg shells which have been examined so far. These analyses and treatment with enzymes indicate that the chitin layer is a chitin–protein complex.Experiments on the permeability of eggs of M. javanica at different temperatures indicate that changes in permeability are not due to the melting of a single lipid with a distinct melting point as had been thought in the past. We have found that Arrhenius activation energies calculated from the two slopes of an Arrhenius plot were 17·8 kcal/mol and 43·0 kcal/mol respectively, the transition from one to the other taking place at 62°C. We think that these changes are due to changes in the properties of lipoprotein membranes in the lipid layer. These membranes appear to be of paramount importance in controlling the permeability of the nematode egg shell.

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Ultrastructural observations on oogenesis and shell formation in Gyrinicola batrachiensis (Walton, 1929) (Nematoda: Oxyurida)

Parasitology ◽

10.1017/s003118200005068x ◽

1983 ◽

Vol 86 (3) ◽

pp. 489-499 ◽

Cited By ~ 6

Author(s):

M. L. Adamson

Keyword(s):

Dorsal Horn ◽

Lipid Droplets ◽

Reproductive Tract ◽

Ventral Horn ◽

Multivesicular Bodies ◽

Shell Formation ◽

Lipid Layer ◽

Protein Coat ◽

Large Numbers ◽

Egg Shell

SUMMARYIndividual females of Gyrinicola batrachiensis produce 2 types of eggs: thin-shelled auto-infective eggs are produced in the ventral horn of the reproductive tract and thick-shelled eggs (transmission agents) are produced in the dorsal horn. Fine structure of oogenesis and egg-shell formation in the 2 horns of the reproductive tract were studied and compared. Early stages of oogenesis were similar in both horns but mature oocytes differed considerably. Those in the dorsal horn were larger than those in the ventral horn; they contained large numbers of lipid droplets, peripheral patches of glycogen and several types of cytoplasmic granules presumably acting as yolk or playing a role in shell formation. Mature oocytes in the ventral horn contained large amounts of glycogen, relatively few lipid droplets and large multivesicular bodies. Four shell layers formed around ova in the dorsal horn: a vitelline layer, a lipid layer, a chitinous layer and an outer protein coat similar to that described in other oxyurids. Only the vitelline layer formed around thin-shelled eggs. Thick-shelled eggs did not embryonate in utero but thin-shelled eggs nearest the vagina contained larvae. The first moult in eggs of G. batrachiensis was described in a previous communication and it is suggested here that the thin fibrous layer loosely applied to the cuticle of infective larvae in thin-shelled eggs is the moulted 2nd-stage cuticle.

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The tylenchid (Nematoda) egg shell: structure, composition and permeability

Parasitology ◽

10.1017/s0031182000058431 ◽

1976 ◽

Vol 72 (1) ◽

pp. 19-28 ◽

Cited By ~ 4

Author(s):

Alan F. Bird ◽

M. A. McClure

Keyword(s):

Basic Structure ◽

Vitelline Membrane ◽

Chemical Components ◽

Rotylenchulus Reniformis ◽

Lipid Layer ◽

Tylenchulus Semipenetrans ◽

Different Temperatures ◽

Egg Shells ◽

Egg Shell ◽

Lipid Layers

The fine structure of egg shells of four different genera belonging to the order Tylenchida has been examined. The species examined were Meloido-gyne javanica, Rotylenchulus reniformis, Tylenchulus semipenetrans and Pratylenchus minyus. They are all similar in their basic structure, being composed of vitelline membrane, chitin and lipid layers, but there is considerable variability in the thickness of these layers.We have retained the conventional nomenclature because of its convenience, but it is clear that these layers have a variety of chemical components. However, they do appear to contain the compounds from which they take their name. Thus chitin occurs in the chitin layer, and lipid in the lipid layer. The latter is removed by the technique used in isolating the shell from the egg. Chemical analysis of the hydrolysis products of these shells has revealed a high (35 %) proline content which appears to be a characteristic of those nematode egg shells which have been examined so far. These analyses and treatment with enzymes indicate that the chitin layer is a chitin-protein complex.Experiments on the permeability of eggs of M. javanica at different temperatures indicate that changes in permeability are not due to the melting of a single lipid with a distinct melting point as had been thought in the past. We have found that Arrhenius activation energies calculated from the two slopes of an Arrhenius plot were 17·8 kcal/mol and 43·0 kcal/mol respectively, the transition from one to the other taking place at 62°C. We think that these changes are due to changes in the properties of lipoprotein membranes in the lipid layer. These membranes appear to be of paramount importance in controlling the permeability of the nematode egg shell.

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Ultrastructural and cytochemical studies of GER-bodies in the intrauterine eggs of Wenyonia virilis Woodland, 1923 (Cestoda, Caryophyllidea)

Acta Parasitologica ◽

10.2478/s11686-011-0011-4 ◽

2011 ◽

Vol 56 (1) ◽

Cited By ~ 11

Author(s):

Daniel Młocicki ◽

Zdzisław Świderski ◽

John Mackiewicz ◽

Mohammed Ibraheem

Keyword(s):

Endoplasmic Reticulum ◽

Positive Reaction ◽

Granular Endoplasmic Reticulum ◽

Cytochemical Analysis ◽

Dense Cytoplasm ◽

Egg Shell ◽

Glycogen Particles

AbstractUltrastructural and cytochemical characteristics of GER-bodies observed in the vitellocyte cytoplasm of the intrauterine eggs of the caryophyllidean cestode Wenyonia virilis are described. In this species GER-bodies were observed only in the cytoplasm of vitellocytes, surrounded by a newly formed egg-shell. They are composed of spherical areas of condensed, electron-dense cytoplasm which contains concentrically arranged parallel lamellae of granular endoplasmic reticulum (GER), forming characteristic balls of different sizes. Each GER-body is surrounded by numerous free ribosomes, polyribosomes, α-glycogen rosettes and large mitochondria. Results of cytochemical analysis by means of PATSC-SP test for polysaccharides indicated that glycogen is absent within the GER-bodies, however, a strongly positive reaction was observed only in large aggregations of α-glycogen rosettes and β-glycogen particles, localised usually near GER-bodies.

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Trichuris muris: structure and formation of the egg-shell

Parasitology ◽

10.1017/s0031182000001293 ◽

1984 ◽

Vol 89 (2) ◽

pp. 263-274 ◽

Cited By ~ 6

Author(s):

C. M. Preston ◽

T. Jenkins

Keyword(s):

Female Worm ◽

Light And Electron Microscopy ◽

Particulate Material ◽

Variable Number ◽

Shell Formation ◽

Lipid Layer ◽

Trichuris Muris ◽

Protein Coat ◽

Sperm Entry ◽

Egg Shell

SummaryThe development of the egg-shell of the trichuroid nematode, Trichuris muris, was observed by light and electron microscopy. Initial stages of shell formation occurred immediately following sperm entry into the oocyte in the spermatheca of the female worm. The external vitelline layer separated from the oolemma, reticulate oocyte granules were discharged into the resultant perivitelline space and stored glycogen contributed to the formation of the chitinous shell. A lipid layer developed between the inner surface of the chitinous layer and the oolemma. The fully formed egg-shell thus comprised an external vitelline layer, a middle chitinous layer and an inner lipid layer. The outer vitelline layer resembled a unit membrane with strands of particulate material attached to its outer surface. The middle chitinous layer was composed of chitin microfibrils encased in a protein coat; the sheets of microfibrils were arranged as parallel lamellae forming a helicoidal architecture. The inner lipid layer contained a variable number of loosely arranged strands of electron-opaque and less-opaque material.

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