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.

A sense organ in the ventral anterior body wall of the nematode Capillaria hepatica (Bancroft, 1893)

1974 ◽  
Vol 52 (1) ◽  
pp. 21-22 ◽  
Author(s):  
K. A. Wright ◽  
J. Chan
Keyword(s):  
Body Wall ◽  
Sense Organ ◽  
Nerve Ring ◽  
The Body ◽  
Capillaria Hepatica ◽  
Pore Opening ◽  
Anterior Body

A sense organ, located just posterior to the nerve ring in the ventral line of the body wall of Capillaria hepatica, is described. It consists of a pore opening through the cuticle to a cuticle-lined chamber into which four dendritic processes extend. The structure of the organ suggests that it may be chemoreceptive.

scholarly journals Ultrastructure of the buccal capsule in the adult female Anguillicoloides crassus (Nematoda: Anguillicolidae)

2010 ◽  
Vol 47 (3) ◽  
pp. 170-178 ◽  
Author(s):  
M. Bruňanská ◽  
H. Fagerholm ◽  
F. Moravec ◽  
Z. Vasilková
Keyword(s):  
Adult Female ◽  
Cross Sections ◽  
Body Wall ◽  
Buccal Capsule ◽  
The Body ◽  
Transmission Electron ◽  
Junctional Complexes ◽  
Marginal Cells ◽  
First Time ◽  
Anguillicoloides Crassus

Abstract The fine structure of the buccal capsule of the adult female nematode Anguillicoloides crassus (Spirurina) was studied for the first time. Results are based on serial section (longitudinal and transverse) light and transmission electron microscopy. The buccal capsule of A. crassus is a cuticular-lined structure. It can be divided into three main parts: cheilostom, gymnostom and stegostom. The cheilostom is the anterior region of the buccal capsule with the cuticular lining continuous with the body wall cuticle and underlain by epidermal syncytia. The gymnostom is a cuticular region with portions of it very electron dense and underlain by arcade syncytia. A dense circumoral cylinder together with the circumpharyngeal ring represent the prominent characters of the gymnostom. The stegostom is formed by anterior pharyngeal cuticle underlain by muscular radial cells and epithelial marginal cells. The cephalic cuticle of A. crassus makes a direct contact with the pharyngeal cuticle at the base of the circumoral cylinder, within a circumpharyngeal ring containing projections of pharyngeal muscular and marginal cells. The circumoral cylinder, circumpharyngeal ring and pharynx are connected to the body epidermis by junctional complexes. The buccal capsule includes occasionally 3 projections of the pharynx evidently observed in serial cross sections. These ultrastructural characters may provide useful data for comparative, functional as well as evolutionary studies within the Chromadorea.

On the Fine Structure of the Alimentary Tract ofCephalodiscus gracilis(Pterobranchia, Hemichordata)

1986 ◽  
Vol 67 (2) ◽  
pp. 87-95 ◽  
Author(s):  
Peter Noel Dilly ◽  
Ulrich Welsch ◽  
Gerd Rehkämper
Keyword(s):  
Fine Structure ◽  
Alimentary Tract

scholarly journals The Fine Structure of Some Blood Vessels of the Earthworm, Eisenia foetida

1960 ◽  
Vol 7 (4) ◽  
pp. 717-724 ◽  
Author(s):  
Kiyoshi Hama
Keyword(s):  
Fine Structure ◽  
Basement Membrane ◽  
Body Wall ◽  
Circular Muscle ◽  
Muscle Layer ◽  
Eisenia Foetida ◽  
Longitudinal Muscle Layer ◽  
Cell Processes ◽  
Body Wall Musculature ◽  
Blood Pigment

The fine structure of the main dorsal and ventral circulatory trunks and of the subneural vessels and capillaries of the ventral nerve cord of the earthworm, Eisenia foetida, has been studied with the electron microscope. All of these vessels are lined internally by a continuous extracellular basement membrane varying in thickness (0.03 to 1 µ) with the vessel involved. The dorsal, ventral, and subneural vessels display inside this membrane scattered flattened macrophagic or leucocytic cells called amebocytes. These lie against the inner lining of the basement membrane, covering only a small fraction of its surface. They have long, attenuated branching cell processes. All of these vessels are lined with a continuous layer of unfenestrated endothelial cells displaying myofilaments and hence qualifying for the designation of "myoendothelial cells." The degree of muscular specialization varies over a spectrum, however, ranging from a delicate endowment of thin myofilaments in the capillary myoendothelial cells to highly specialized myoendothelial cells in the main pulsating dorsal blood trunk, which serves as the worm's "heart" or propulsive "aorta." The myoendothelial cells most specialized for contraction display well organized sarcoplasmic reticulum and myofibrils with thick and thin myofilaments resembling those of the earthworm body wall musculature. In the ventral circulatory trunk, circular and longitudinal myofilaments are found in each myoendothelial cell. In the dorsal trunk, the lining myoendothelial cells contain longitudinal myofilaments. Outside these cells are circular muscle cells. The lateral parts of the dorsal vessels have an additional outer longitudinal muscle layer. The blood plasma inside all of the vessels shows scattered particles representing the circulating earthworm blood pigment, erythrocruorin.

The ultrastructure of the cuticle of the nematode Syphacia obvelata (Rudolphi, 1802). II. Modifications of the cuticle in the head end

1973 ◽  
Vol 51 (2) ◽  
pp. 197-202 ◽  
Author(s):  
T. A. Dick ◽  
K. A. Wright
Keyword(s):  
Body Wall ◽  
Buccal Capsule ◽  
The Body ◽  
Head Region ◽  
Limited Region ◽  
Structural Role ◽  
Mouth Cavity ◽  
Median Zone ◽  
Syphacia Obvelata ◽  
Somatic Muscles

The head region of the pinworm Syphacia obvelata (Rudolphi, 1802) has been examined to determine the nature of modification of the cuticle responsible for, or associated with, lips and buccal capsule, cephalic papillae and amphids, cephalic inflations, and cervical alae. The median zone of the cuticle was found to be the most modified and variation in the extent and distribution of striated material is compatible with its proposed structural role. The variations found are probably related to compensation for stresses that may develop in the cuticle during the complex movements of the head end. Lips are only inconspicuous expansions of the body wall cuticle, while esophageal cuticle is strikingly different in appearance. It is proposed to refer to all regions of the mouth cavity bounded by both the lips and esophagus as the buccal capsule while only the limited region bounded by body wall cuticle may be referred to as stoma. A mechanism involving three groups of intrahypodermal cytoskeletal filaments attached to the tips of somatic muscles, esophagus, and cuticle is proposed to move the lips.

Some aspects of the fine structure of the alimentary tract of the infective larva of Breinlia sergenti (Nematoda: Filarioidea)

1975 ◽  
Vol 5 (2) ◽  
pp. 171-176 ◽  
Author(s):  
Mulkit Singh ◽  
R. Kanagasuntheram ◽  
Beng-Chuan Ho ◽  
Eu-Hian Yap ◽  
Heng-Leong Chan
Keyword(s):  
Fine Structure ◽  
Alimentary Tract ◽  
Infective Larva

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.

The identification and estimation of acetylcholine in three parasitic nematodes (Ascaris lumbricoides, Litomosoides carinii, and the microfilariae of Dirofilaria repens)

Parasitology ◽  
1955 ◽  
Vol 45 (3-4) ◽  
pp. 287-294 ◽  
Author(s):  
Helen Mellanby
Keyword(s):  
Ascaris Lumbricoides ◽  
Body Wall ◽  
Nerve Ring ◽  
The Body ◽  
Dirofilaria Repens ◽  
Parasitic Nematodes ◽  
Wet Weight

1. Extracts made from whole nematode worms, Litomosoides carinii, and from Ascaris ‘heads’ and body wall tissue, contain a substance similar to acetylcholine.2. In the case of extracts from Litomosoides whole worms, this substance was shown to be probably acetylcholine itself.3. Tissue from the anterior end of Ascaris (including the nerve ring), contains about 15 times as much acetylcholine as the body wall preparations; i.e. 0·39μg./g. as compared with 0·025μg/g. of wet weight.4. There appeared to be rather more acetylcholine present in the Litomosoides males than in the females; 0·92μg./g. as compared with 0·63μg./g. of wet weight.5. The microfilariae of the filariid nematode of the dog, Dirofilaria repens, contain as much as 2·4;μg./g. of acetylcholine. In this respect it resembles some other motile parasites of the blood, such as trypanosomes.

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