Fine structure of the egg envelopes inSilo mediterraneus saturniae(Trichoptera, Goeridae)

2000 ◽  
Vol 67 (2) ◽  
pp. 141-146
Author(s):  
Maria Clara Bicchierai ◽  
Elda Gaino
Keyword(s):  
Fine Structure ◽  
Egg Envelopes

Fine structure of egg envelopes in some viviparous goodeid fishes, with comments on the relation of envelope thinness to viviparity

1993 ◽  
Vol 71 (1) ◽  
pp. 91-97 ◽  
Author(s):  
Rüdiger Riehl ◽  
Hartmut Greven
Keyword(s):  
Fine Structure ◽  
Electron Microscope ◽  
Mode Of Reproduction ◽  
Zona Radiata ◽  
Complex Envelope ◽  
Egg Envelope ◽  
Egg Envelopes

The egg envelope (zona radiata) of the full-grown oocytes before fertilization was examined by electron microscope in eight viviparous species of Goodeidae (Cyprinodontiformes) from the Mexican plateau. The egg envelope is composed of a homogeneous electron-dense zona radiata perforated mainly by oocyte microvilli. The thickness of the zona radiata ranged from 0.5 μm (Xenoophorus captivus) to 1.5 μm (Ameca splendens). Egg envelopes of Ataeniobius toweri and Ilyodon xantusi appeared to have two layers, tentatively described as a zona radiata interna and a zona radiata externa. The most complex envelope was observed in Girardinichthys multiradiatus, which showed a small filamentous zona radiata interna and an electron-dense zona radiata externa covered by an additional flocculent layer, which is probably the gelatinous coat found in many eggs. The egg envelope of Ameca splendens, Girardinichthys viviparus, and Xenotoca eiseni displayed short external processes resembling attaching filaments, which are known from eggs of substrate-spawning teleosts. The thickness and differentiation of the zona radiata in other viviparous teleosts are compared and discussed with reference to mode of reproduction.

Fine structure of egg envelopes and the activation changes of cortical alveoli in the river lamprey, Lampetra fluviatilis

Development ◽  
1968 ◽  
Vol 19 (3) ◽  
pp. 311-318
Author(s):  
Björn A. Afzelius ◽  
Lennart Nicander ◽  
Inger Sjödén
Keyword(s):  
Fine Structure ◽  
Chemical Composition ◽  
Present Knowledge ◽  
Egg Cell ◽  
Lampetra Fluviatilis ◽  
Animal Groups ◽  
Zona Radiata ◽  
Egg Envelope ◽  
River Lamprey ◽  
Egg Envelopes

Most eggs are surrounded by several prominent envelopes which have been given names depending on their origin, structure or chemical composition. As our present knowledge of these envelopes is very fragmentary, the results of attempts to homologize the different layers between different animal groups are still open to debate. The nomenclature in this field is quite confusing. According to Raven (1961) the.egg membranes may be divided into ‘primary egg membranes’, formed in the ovary by the egg cell, ‘secondary egg membranes’ formed in the ovary by the follicle epithelium, and ‘tertiary egg membranes’ formed in the genital ducts after ovulation. The egg envelopes in the river lamprey, as in fish, are supposed to be primary egg membranes, although there is no certainty on this point. At least three distinct layers can be distinguished in the egg envelope of this species. Common to two of them is the presence of radial striations, which justifies the name ‘zona radiata’.

Fine Structure of Platelet Interaction with a New Microcrystalline Collagen Preparation

1974 ◽  
Vol 32 ◽  
pp. 58-59
Author(s):  
W. H. Zucker ◽  
R. G. Mason
Keyword(s):  
Fine Structure ◽  
Platelet Aggregation ◽  
Hydrochloric Acid ◽  
Whole Blood ◽  
Platelet Adhesion ◽  
Hemostatic Agent ◽  
Native Collagen ◽  
Fibrillar Morphology ◽  
Clinical Interest ◽  
New Form

Platelet adhesion initiates platelet aggregation and is an important component of the hemostatic process. Since the development of a new form of collagen as a topical hemostatic agent is of both basic and clinical interest, an ultrastructural and hematologic study of the interaction of platelets with the microcrystalline collagen preparation was undertaken.In this study, whole blood anticoagulated with EDTA was used in order to inhibit aggregation and permit study of platelet adhesion to collagen as an isolated event. The microcrystalline collagen was prepared from bovine dermal corium; milling was with sharp blades. The preparation consists of partial hydrochloric acid amine collagen salts and retains much of the fibrillar morphology of native collagen.

Pituitary Follicular Cells: Their Origin, Possible Function and Fate

1974 ◽  
Vol 32 ◽  
pp. 34-35
Author(s):  
E. Horvath ◽  
K. Kovacs ◽  
G. Penz ◽  
C. Ezrin
Keyword(s):  
Fine Structure ◽  
Secretory Granules ◽  
Follicular Cells ◽  
Human Pituitary ◽  
Rat Pituitary ◽  
Pituitary Glands ◽  
Junctional Complexes

Follicular structures, in the rat pituitary, composed of cells joined by junctional complexes and possessing few organelles and few, if any, secretory granules, were first described by Farquhar in 1957. Cells of the same description have since been observed in several species including man. The importance of these cells, however, remains obscure. While studying human pituitary glands, we have observed wide variations in the fine structure of follicular cells which may lead to a better understanding of their morphogenesis and significance.

Ultrastructure and Staining of Developing Elastic Tissue

1971 ◽  
Vol 29 ◽  
pp. 244-245
Author(s):  
E. N. Albert
Keyword(s):  
Fine Structure ◽  
Phosphotungstic Acid ◽  
Staining Method ◽  
Rat Aorta ◽  
Uranyl Acetate ◽  
The Other ◽  
Elastic Fibers ◽  
Elastic Tissue ◽  
Lead Citrate ◽  
New Born

Silver tetraphenylporphine sulfonate (Ag-TPPS) was synthesized in this laboratory and used as an electron dense stain for elastic tissue (Fig 1). The procedures for the synthesis of tetraphenylporphine sulfonate and the staining method for mature elastic tissue have been described previously.The fine structure of developing elastic tissue was observed in fetal and new born rat aorta using tetraphenylporphine sulfonate, phosphotungstic acid, uranyl acetate and lead citrate. The newly forming elastica consisted of two morphologically distinct components. These were a central amorphous and a peripheral fibrous. The ratio of the central amorphous and the peripheral fibrillar portion changed in favor of the former with increasing age.It was also observed that the staining properties of the two components were entirely different. The peripheral fibrous component stained with uranyl acetate and/or lead citrate while the central amorphous portion demonstrated no affinity for these stains. On the other hand, the central amorphous portion of developing elastic fibers stained vigorously with silver tetraphenylporphine sulfonate, while the fibrillar part did not (compare figs 2, 3, 4). Based upon the above observations it is proposed that developing elastica consists of two components that are morphologically and chemically different.

The Dermal Glands of Rhodnius Prolixus

1969 ◽  
Vol 27 ◽  
pp. 258-259
Author(s):  
J. E. Lai-Fook
Keyword(s):  
Fine Structure ◽  
Secretory Activity ◽  
Rhodnius Prolixus ◽  
Outermost Layer ◽  
Cement Layer ◽  
Dermal Glands

Dermal glands are epidermal derivatives which are reported to secrete either the cement layer, which is the outermost layer of the epicuticle or some component of the moulting fluid which digests the endocuticle. The secretions do not show well-defined staining reactions and therefore they have not been positively identified. This has contributed to another difficulty, namely, that of determining the time of secretory activity. This description of the fine structure of the developing glands in Rhodnius was undertaken to determine the time of activity, with a view to investigating their function.

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