Fine structure studies of the ocelli of Polyorchis penicillatus (Hydrozoa, Anthomedusae) and their connection with the nerve ring

Zoomorphology ◽  
1982 ◽  
Vol 99 (2) ◽  
pp. 117-129 ◽  
Author(s):  
C. L. Singla ◽  
C. Weber
Keyword(s):  
Fine Structure ◽  
Nerve Ring ◽  
Polyorchis Penicillatus

The fine structure of the esophagus of some trichuroid nematodes. II. The buccal capsule and anterior esophagus of Capillaria hepatica (Bancroft, 1893)

1974 ◽  
Vol 52 (1) ◽  
pp. 47-58 ◽  
Author(s):  
K. A. Wright
Keyword(s):  
Fine Structure ◽  
Body Wall ◽  
Alimentary Tract ◽  
Buccal Capsule ◽  
Nerve Ring ◽  
Cellular Organization ◽  
Marginal Cell ◽  
Capillaria Hepatica ◽  
Marginal Cells ◽  
Muscle Sheath

The anterior alimentary tract of Capillaria hepatica participates in formation of the buccal capsule and shows different cellular organization along its length. The buccal capsule is composed of both invaginated body-wall cuticle (stomodeum) and the expanded anterior esophageal cuticle and contains a small dorsal stylet. Suction action of the buccal capsule is controlled by two sets of buccal dilator muscles and three esophageal suspensor muscles. The anteriormost esophagus consists of three elongate marginal cells and three units of radial tissue. At the level of the nerve ring, radial tissue divides into six units, two between each marginal cell. Posterior to the nerve ring, the esophagus is surrounded by a muscle sheath that continues for the rest of the esophagus. Radial tissue has both longitudinal and radial myofilaments, as does the midregion of marginal cells. Marginal cells terminate some distance posterior to the nerve ring and radial-tissue units fuse to form a single cytoplasmic mass around the cuticle. Posteriorly, myofilaments are reduced from the radial tissue. Peristalsis of the esophagus is probably maintained by the outer muscle sheath. Three nerve cells are located in the wall of the esophagus, posterior to die level of marginal cells, and send processes both anteriorly and posteriorly. Synapses between axons and radial tissue have been identified only in the anterior esophagus. Because of the degree of organization of myofilaments, and the presence of sacroplasmic reticulum diads and synapses, it is suggested that the region of the esophagus just posterior to the nerve ring may serve as a pacemaker region for esophageal activity. Three satellite cells located in the anterior esophagus may represent vestigial stylet retractor muscles.

The ultrastructure of the anterior end of male Onchocerca volvulus: papillae, amphids, nerve ring and first indication of an excretory system in the adult filarial worm

Parasitology ◽  
1996 ◽  
Vol 113 (1) ◽  
pp. 71-85 ◽  
Author(s):  
G. Strote ◽  
I. Bonow ◽  
S. Attah
Keyword(s):  
Fine Structure ◽  
Age Distribution ◽  
Mouth Opening ◽  
Cell Types ◽  
Nerve Ring ◽  
Onchocerca Volvulus ◽  
Head Region ◽  
Filarial Worm ◽  
The Central Nervous System ◽  
Morphological Differences

SUMMARYA detailed morphological investigation of the anterior sensory organs, the nerve ring and a glomerulus-like structure in male Onchocerca volvulus was performed by means of electron microscopy. The 8 head papillae are arranged in the common 4 + 4 pattern of most filarial worms in circles around the mouth opening. The amphidial openings are found between the circles of inner and outer papillae on both sides of the mouth. Inside, several additional nerve axons are seen in the tissue of the anterior tip not related to one of the identified papillar structures. The inner and outer papillae exhibit a remarkably different fine structure, and are part of a complex system of at least 2 different receptor cell types at the anterior tip of the worm. The amphidial channel contains 8 modified cilia; accessory axons are associated with the cytoplasm of the sheath cell. The anterior nerve ring of male worms is located about 150 µm posterior from the outermost tip of the head region. It consists of several fibres coiled around the oesophagus. The comparison of the fine structure of the central nervous system did not show the expected morphological differences associated with the heterogeneous age distribution in the natural worm population. This was in contrast to previous findings with respect to tissues in different parts of the worm. The study also provides the first evidence that suggests the existence of an excretory organ in a filarial worm in the region of the anterior nerve ring. Paired glomerulus-like structures in the lateral chords and a canal formed by a projection of the basal zone of the cuticle were identified.

scholarly journals Radial Symmetry and the Organization of Central Neurones in a Hydrozoan Jellyfish

1984 ◽  
Vol 110 (1) ◽  
pp. 69-90 ◽  
Author(s):  
A. N. SPENCER ◽  
S. A. ARKETT
Keyword(s):  
Action Potentials ◽  
Functional Organization ◽  
Lucifer Yellow ◽  
Morphological Characteristics ◽  
Radial Symmetry ◽  
Nerve Ring ◽  
Rapid Reduction ◽  
Potential Oscillations ◽  
Polyorchis Penicillatus ◽  
Motor Neurones

1. Two discrete networks of neurones in the outer nerve-ring of Polyorchis penicillatus can be identified by their physiological and morphological characteristics. 2. The ‘B’ system is characterized by the regular, spontaneous firing pattern that can be recorded intracellularly. Bursts of up to six spikes are produced in response to a rapid reduction in the light intensity. 3. Neurones of the ‘B’ system are electrically coupled to one another. 4. Action potentials in the ‘B’ system produce unitary EPSPs in swimming motor neurones and in epithelial cells overlying the outer nerve-ring. 5. Lucifer Yellow injected into a ‘B’ neurone diffuses rapidly through neighbouring neurones to reveal a condensed network of neurones in the centre of the nerve-ring and a more diffuse network passing up and around each tentacle. 6. The ‘O’ system is characterized by very regular (approx. 1 Hz), spontaneous membrane potential oscillations. Action potentials are never recorded. 7. Neurones of the ‘O’ system are electrically coupled to one another. 8. There is evidence of interaction between the ‘O’ system and swimming motor neurones. 9. Lucifer Yellow injected into an ‘O’ neurone diffuses through member neurones to show an anastomosing network of neurones extending across the width of the outer nerve-ring and tracts of neurones extending up the sides of each tentacle towards the ocelli. 10. The restriction of injected Lucifer Yellow to each of the networks and the blockade of interaction between systems by Mg2+ anaesthesia are evidence that signalling between different central networks is by chemical means. 11. The adaptive advantages of this type of functional organization of central neurones in radially symmetrical animals are discussed. Such an organization is compared with that found in bilateral animals.

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.

The Ultrastructure of Myocardial Cells in Normal and Cardiac Lethal Mutant Mexican Axolotls, (Ambystoma Mexicanum)

1970 ◽  
Vol 28 ◽  
pp. 62-63
Author(s):  
Larry F. Lemanski ◽  
Eldridge M. Bertke ◽  
J. T. Justus
Keyword(s):  
Fine Structure ◽  
Heart Development ◽  
Osmium Tetroxide ◽  
Picric Acid ◽  
Ambystoma Mexicanum ◽  
Recessive Mutation ◽  
Acid Mixture ◽  
Myocardial Cells ◽  
Lethal Mutant ◽  
Mexican Axolotl

A recessive mutation has been recently described in the Mexican Axolotl, Ambystoma mexicanum; in which the heart forms structurally, but does not contract (Humphrey, 1968. Anat. Rec. 160:475). In this study, the fine structure of myocardial cells from normal (+/+; +/c) and cardiac lethal mutant (c/c) embryos at Harrison's stage 40 was compared. The hearts were fixed in a 0.1 M phosphate buffered formaldehyde-glutaraldehyde-picric acid-styphnic acid mixture and were post fixed in 0.1 M s-collidine buffered 1% osmium tetroxide. A detailed study of heart development in normal and mutant embryos from stages 25-46 will be described elsewhere.

Sign in / Sign up

Export Citation Format

Share Document