The skeletomusculature of siphonostomatoid copepods, with an analysis of adaptive radiation in structure of the oral cone

1990 ◽  
Vol 328 (1246) ◽  
pp. 167-212 ◽  
Keyword(s):  
Proximal Part ◽  
Trunk Muscles ◽  
Pedigerous Somite ◽  
Free Living ◽  
Food Material ◽  
Oral Cone ◽  
Genital Complex ◽  
Adductor Muscles ◽  
Outer Lobe ◽  
Intrinsic Muscles

The skeletomusculature of a primitive siphonostomatoid copepod, Hyalopontius typicus , is described and compared with that of a relatively advanced siphonostomatoid, Lepeophtheirus pectoralis , an ectoparasite of flatfishes. The comparison is used to assess how adaptation to parasitism has affected the morphology and musculature of the appendages. Anatomy has been related to presumed function wherever possible, and functional interpretations are presented for the feeding apparatus of both species and for a range of other siphonostomatoids. The longitudinal trunk muscles of Hyalopontius are arranged in paired dorsal and ventral bundles, as in free-living copepods, but are smaller and less powerful. A further reduction takes place in Lepohtirus , and is presumably correlated with a limited swimming ability. The tagmosis of Hyalopontius is typically podoplean, with the prosome-urosome junction between fourth and fifth pedigerous somites. Hyalopontius possesses a cephalothorax comprising the cephalosome plus the first pedigerous somite. The tagmosis of Lepeophtheirus is modified and the prosomeurosome junction is no longer functional. In adult females the fourth pedigerous somite forms a waist-like region separating anterior cephalothorax from posterior genital complex. The shield-like cephalothorax comprises the cephalosome plus the first three pedigerous somites. The fifth pedigerous, genital and probably the first abdominal somites are fused to form a genital complex. The eudactylinid genus Bariaka is identified as one of the only two siphonostomatoids that possess a free genital somite, not incorporating the first abdominal somite. The structure and musculature of the sternal furca of Lepeophtheirus is described. It is concluded that the furca is an elaboration of the median intersomitic sclerite lying between the maxillipedal and first pedigerous somites. The musculature of the sternal furca is derived from the ventral longitudinal trunk muscles. The musculature of the cephalosomic appendages of siphonostomatoids is reduced compared with that of free-living copepods. The mandibles and maxillules increasingly lose any adduction-abduction movements. In Hyalopontius some adduction of the mandible is possible and extrinsic adductor muscles originating on the anterior cephalic tendon are retained. These are absent from Lepeophtheirus . The maxillules have no ventral extrinsic muscles in Hyalopontius and few dorsal muscles. In Lepeophtheirus there are no maxillulary muscles. The antennae, maxillae and maxillipeds are all basically subchelate and their intrinsic muscles are arranged in antagonistic extensor and flexor groups. These commonly insert on an apophysis that extends proximally from the base of the subchela. A pattern of homologies for the segmental composition of the limbs of the siphonostomatoids is established, based on evidence from their musculature. The inner lobe of the maxillule is homologous with the praecoxal arthrite of other copepods, the outer lobe with the rest of the palp. The proximal segment of the maxilla is the syncoxa. The distal claw represents the basis and its proximal endite, and there is no vestige of the endopod in any siphonostomatoid. The subchela of the maxilliped is derived from the endopod and the endopodal segments are often fused to each other and to the distal claw. The oral cone in a range of siphonostomatoid families is described. Adapdve radiation in feeding mechanisms mainly involves modification of the oral cone and maxillules, rather than of the appendages used for attachm ent to the host. In Hyalopontius , Pontoeciella and Entomopsyllus the oral cone is specialized for fluid feeding. There are efficient seals both around the distal opening of the cone and along the labrum -labium boundary. Suction pressure is produced by labral muscles concentrated in the proximal part of the cone. In Lepeophtheirus the oral cone is specialized for surface grazing and it lacks efficient sealing mechanisms distally and along the labrum -labium boundary. Food material is transported up the oral cone by sequential contraction of labral muscles. In adult Lernaeocera the oral cone acts as an enlarged oral disc forming a feeding seal distally. Suction is generated by oesophageal peristalsis. The musculature of the swimming legs of Lepeophtheirus is described. Several remotor muscles insert on the ventral body wall remote from the basal foramina of the swimming legs. These muscles probably function as a dorsoventral tensors, and assist in creating suction beneath the disc of the cephalothorax. The posterior sinuses on the rear margin of the cephalothorax function as outlet valves during swimming. They are opened and closed by sinus muscles derived from modified promotor muscles of the second swimming legs.

On the anatomy of the misophrioid copepods, with special reference to Benthomisophria palliata Sars

1982 ◽  
Vol 297 (1086) ◽  
pp. 125-181 ◽  
Keyword(s):  
The Body ◽  
Trunk Muscles ◽  
Gut Contents ◽  
Phylogenetic Position ◽  
Muscle Fibres ◽  
Similar Data ◽  
Pedigerous Somite ◽  
Sequence Of Events ◽  
Organ Systems ◽  
Intrinsic Muscles

The misophrioids are a small but phylogenetically important order of copepods, comprising only three species, which exhibit a mosaic of characters drawn from both gymnoplean and podoplean lineages. The skeletomuscular system of Benthomisophria palliata is described in detail and comparative observations are made on B. cornuta and Misophria pallida . All were found to possess a carapace-like posterior extension of the cephalosome which completely encloses, both dorsally and laterally, the first pedigerous somite beneath. This structure is a posterior outgrowth of the maxilliped-bearing somite and is not derived from the tergite of the pedigerous somite that it encloses. It may represent a modification of the somitic hyaline frill common to many copepods. Its presence is apparently associated with the ability of Benthomisophria to gorge itself until virtually all the free space within the prosome is occupied by the gut. The gut contents of B. palliata reveal that it feeds on relatively large food particles. The probable feeding mechanism is inferred from the ranges of movement possible at each of the joints of the feeding appendages and from their musculature. The probable swimming mechanism is also inferred from similar data for the thoracic limbs. The skeletomusculature of other copepod groups is compared with that of Benthomisophria . The extrinsic muscles of the cephalic appendages and both the extrinsic and intrinsic muscles of the swimming legs were found to be relatively uniform throughout the Copepoda. The longitudinal trunk muscles and intrinsic muscles of the cephalic appendages were found to be more subject to modification during adaptive radiation in habit and feeding strategy respectively. Both species of Benthomisophria exhibit ornamentation of the integument. This is described and a strengthening role is attributed to the intricate system of lamellae and ridges present. Laterally on the cephalosome of Benthomisophria species are areas of funnel-shaped cone organs standing erect from the body surface and bearing a spherical globule of secretion distally. They are positioned so that the long setae of the reflexed antenna and mandibular palp sweep over them. It is concluded that the secretion is spread over the surface of the carapace-like structure by the setae. Its function may be protective. The gross anatomy of the other organ systems is described. The highly distensible gut has large lateral caecae which can expand to accommodate large amounts of food. The musculature of the hindgut is described, as is the postulated sequence of events during defaecation. Adult B. palliata possess paired antennary glands as the functional excretory organs. The maxillary gland is absent. In other copepod groups the maxillary gland is the functional excretory organ of the adult. The central nervous system is described. The complete absence of the nauplius eye throughout the life cycle of misophrioids is noted. The heart is absent from B. palliata . In Misophria pallida it is a barrel-shaped structure about 40 µm long, with weakly muscular walls. It has anterior and posterior ostia only and is suspended from the dorsal body wall by short muscle fibres. The reproductive system is described in both sexes. Male and female have paired gonads, ducts and genital openings. The oviducts open into cavities (genital antra) within the genital somite, which are closed off externally by the plate formed from the fused sixth legs. The male possesses relatively simple vasa deferentia which are poorly differentiated into functional zones. The phylogenetic position of the misophrioids is discussed. They exhibit an unusual combination of ancestral, unique and convergent characters which makes assessment of their affinities difficult. It is tentatively suggested that the Misophrioida, which merits ordinal rank, is more closely related to the Harpacticoida than to any other order.

Ultrastructure of the male reproductive system of the free-living marine nematode Paracyatholaimus pugettensis Wieser & Hopper, 1967 (Chromadorida: Cyatholaimidae)

Nematology ◽  
2010 ◽  
Vol 12 (2) ◽  
pp. 255-268 ◽  
Author(s):  
Julia K. Zograf
Keyword(s):  
Epithelial Cells ◽  
Seminal Vesicle ◽  
Reproductive System ◽  
Vas Deferens ◽  
Proximal Part ◽  
Male Reproductive System ◽  
Synthetic Activity ◽  
The Sea Of Japan ◽  
Marine Nematode ◽  
Free Living

AbstractAlthough nematodes are a well studied group of multicellular organisms, until now the only information on the cellular structure of the male reproductive system of marine nematodes is that on the histology of free-living marine nematode from the order Enoplida. The fine structure of the male reproductive system of the free-living marine nematode Paracyatholaimus pugettensis (Chromadorida: Cyatholaimidae) from the Sea of Japan has been studied using TEM. The testis epithelium has a large distal tip cell similar to that described for representatives of the subclass Rhabditia. The epithelial wall of the testis is differentiated along its length. The proximal part of the epithelial tube consists of relatively large cells bearing numerous surface outgrowths that permeate between the developing spermatocytes. The epithelium in the middle region of the testis is formed from extremely flattened cells. The distal part of the testis – the seminal vesicle – is filled with immature spermatozoa and consists of absorptive cells. The seminal vesicle is followed by the vas deferens. The gonoduct is also differentiated along its length, the first third being formed from synthetically active epithelial cells, the two layers of which form a tiled structure. There is no lumen in the gonoduct and it is probable that, due to the tiled structure, the epithelial cells move apart to create space for the spermatozoa during ejaculation. The posterior two-thirds of the duct is surrounded by muscle cells that create the necessary pressure during ejaculation. The enlarged epithelial cells of the vas deferens show vigorous synthetic activity, which is probably involved in the transformation of immature spermatozoa into mature gametes.

Moulting and mating in Lepeophtheirus pectoralis (Copepoda: Caligidae)

1990 ◽  
Vol 70 (2) ◽  
pp. 269-281 ◽  
Author(s):  
Morten Anstensrud
Keyword(s):  
Adult Female ◽  
Anterior Margin ◽  
Ventral Side ◽  
Dorsal Side ◽  
The Body ◽  
Agonistic Behaviour ◽  
Free Living ◽  
Genital Complex ◽  
Frontal Filament ◽  
Receptaculum Seminis

Prior to moulting, the preadult Lepeophtheirus pectoralis produces a temporary frontal filament which attaches the animal to the surface of the host during ecdysis. This filament is extruded from a frontal organ previously thought to have a chemoreceptory function. During ecdysis the exuvium splits at the anterior margin and is shed posteriorly by contractions of the body. After hardening of the exoskeleton the copepod detaches itself from the frontal filament and is free-living on the host during intermoult. Males in precopula position hold on to the dorsal side of the female, with the second antennae grasping the anterior end of the female's genital complex. During the ecdysis of the female, most males release their hold on the female, and are usually found close to her on the host. Copulation occurs between an adult male and an adult female with a hardened exoskeleton. In the copula position the male holds on to the female's genital complex with the second antennae, but now on the ventral side of the female. Two spermatophores are extruded and then transferred simultaneously to the female with the aid of the second pair of swimming legs. Tubes originating from the spermatophores connect them to the orifices of the receptaculum seminis. These tubes seem to grow out of the spermatophores after expulsion. After copulation, the male retains a precopula position before releasing the female. No agonistic behaviour has been observed between a precopulating/copulating male and additional males. However, during the ecdysis of the female, a new male may take over the female, but mating does not seem to be assortative for size in Lepeophtheirus pectoralis.

GROWTH AND DISTRIBUTION OF MUSCLE IN DOUBLE MUSCLED AND NORMAL CATTLE

1985 ◽  
Vol 65 (2) ◽  
pp. 307-318 ◽  
Author(s):  
KARIMA A. SHAHIN ◽  
R. T. BERG
Keyword(s):  
Distal Part ◽  
Muscle Growth ◽  
Spinal Column ◽  
Proximal Part ◽  
Growth Patterns ◽  
Growth Coefficient ◽  
Maturity Type ◽  
Muscle Groups ◽  
Intrinsic Muscles ◽  
Similar Growth

Eighteen Double Muscled (DM), 18 Beef Synthetic (SY) and 18 Hereford (HE) bulls, serially slaughtered from approximately 250 to 800 kg liveweight, were used to determine the influence of maturity type and "double muscling" upon muscle growth patterns and distribution. The left side of each carcass was dissected into major carcass tissues and the weights of individual muscles were obtained and grouped into nine standard anatomical groups. Relative to total side msucle (TSM), breed types tended to have similar growth coefficients for all muscle groups except muscles surrounding the spinal column where HE tended to have a higher growth coefficient than either DM or SY. As TSM increased, the proportion of muscle found in proximal hindlimb, distal hindlimb and distal forelimb decreased (b < 1; P < 0.05), the proportion of muscle in abdominal wall and proximal forelimb remained relatively constant (b = 1; P > 0.05) and the proportion of muscle in thorax to forelimb, neck to forelimb and intrinsic muscles of neck and thorax increased (b > 1; P < 0.05). At the same TSM, compared with the other breed types, DM tended to have more of their muscle in the hip and stifle region but less in the distal parts of both limbs and in neck and thorax. The hyperdevelopment of the large superficial muscles of the proximal part (thigh) and the hypodevelopment of the distal part in the hindlimb give the DM animal the typical 'bottle thigh' appearance. Key words: Bulls (young), muscle growth, muscle distribution, Double Muscled, cattle

The caecum of articulate Brachiopoda

1969 ◽  
Vol 172 (1028) ◽  
pp. 187-201 ◽  
Keyword(s):  
Proximal Part ◽  
Chemical Components ◽  
Lipid Bodies ◽  
Intercellular Spaces ◽  
The Core ◽  
Outer Lobe ◽  
Protein Membrane ◽  
Histochemical Tests ◽  
Boring Organisms ◽  
Peripheral Cells

Caeca, the tubular outgrowths of the mantle of endopunctate articulate brachiopods, which penetrate the shell to connect with the periostracum by a brush, have been examined under the electron microscope and subjected to standard histochemical tests. The brush consists of many tubes with a protein membrane, which permeate a thin canopy of calcite separating the periostracum from the distal head of a caecum; the tubes and space beneath the canopy are filled with mucopolysaccharide. Elongate core cells surrounded by flattened peripheral cells make up the caecal head. The core cells are usually distended with spheroidal inclusions of muco- and glycoprotein, particulate glycogen and protein, and minor lipid bodies. They hang freely into a lumen occupying the stalk-like proximal part of a caecum , while their distal surfaces beneath the brush are microvillous. The peripheral cells are charged with protein inclusions. The lumen with in the caecal stalk is formed after the differentiation of a caecum on the outer lobe of the mantle, as an adjustment to a thickening exoskeleton. Proximally, it is bounded by outer epithelial cells but it extends medially to the basement membrane overlying the connective tissue of the mantle and is continuous laterally with intercellular spaces. The mucopolysaccharide in the brush and beneath the calcite canopy is derived from the core cells, and although no continuous seepage through the periostracum to the shell exterior can be demonstrated, it probably acts as a cement when the periostracum is broken and also inhibits penetration of the shell by boring organisms. The core cells as the principal features of caeca are considered to be storage centres for chemical components circulating with in the mantle.

Ultrastructure of neuromuscular relationships in the canine heartworm (dirofilaria immitis)

1986 ◽  
Vol 44 ◽  
pp. 278-279
Author(s):  
W. L. Steffens ◽  
Nancy B. Roberts ◽  
J. M. Bowen
Keyword(s):  
Dirofilaria Immitis ◽  
Domestic Dogs ◽  
Structural Description ◽  
Pharmacological Effects ◽  
Free Living ◽  
Canine Heartworm ◽  
The World ◽  
Synaptic Region ◽  
Muscle Innervation ◽  
Insight Into

The canine heartworm is a common and serious nematode parasite of domestic dogs in many parts of the world. Although nematode neuroanatomy is fairly well documented, the emphasis has been on sensory anatomy and primarily in free-living soil species and ascarids. Lee and Miller reported on the muscular anatomy in the heartworm, but provided little insight into the peripheral nervous system or myoneural relationships. The classical fine-structural description of nematode muscle innervation is Rosenbluth's earlier work in Ascaris. Since the pharmacological effects of some nematacides currently being developed are neuromuscular in nature, a better understanding of heartworm myoneural anatomy, particularly in reference to the synaptic region is warranted.

Lead and lead toxicity in domestic and free living birds

2003 ◽  
Vol 32 (1) ◽  
pp. 3-13 ◽  
Author(s):  
N. De Francisco ◽  
N. De Francisco ◽  
N. De Francisco
Keyword(s):  
Lead Toxicity ◽  
Free Living

Estimation of EMG activity of trunk muscles in manual lifting tasks based on trunk dynamics using the fuzzy relational rule network

2003 ◽  
Author(s):  
Waldemar Karwowski ◽  
Adam Gaweda ◽  
William S. Marras ◽  
Kermit Davis ◽  
Jacek Zurada
Keyword(s):  
Trunk Muscles ◽  
Emg Activity ◽  
Manual Lifting

Platelet Aggregation in Finnish Men and Its Relation to Fatty Acids in Platelets, Plasma and Adipose Tissue

1985 ◽  
Vol 54 (03) ◽  
pp. 563-569 ◽  
Author(s):  
M K Salo ◽  
E Vartiainen ◽  
P Puska ◽  
T Nikkari
Keyword(s):  
Fatty Acids ◽  
Adipose Tissue ◽  
Fatty Acid Composition ◽  
Fatty Acid ◽  
Platelet Aggregation ◽  
Acid Composition ◽  
Saturated Fatty Acids ◽  
Free Living ◽  
Ω3 Fatty Acids ◽  
Induced Aggregation

SummaryPlatelet aggregation and its relation to fatty acid composition of platelets, plasma and adipose tissue was determined in 196 randomly selected, free-living, 40-49-year-old men in two regions of Finland (east and southwest) with a nearly twofold difference in the IHD rate.There were no significant east-southwest differences in platelet aggregation induced with ADP, thrombin or epinephrine. ADP-induced platelet secondary aggregation showed significant negative associations with all C20-C22 ω3-fatty acids in platelets (r = -0.26 - -0.40) and with the platelet 20: 5ω3/20: 4ω 6 and ω3/ ω6 ratios, but significant positive correlations with the contents of 18:2 in adipose tissue (r = 0.20) and plasma triglycerides (TG) (r = 0.29). Epinephrine-induced aggregation correlated negatively with 20: 5ω 3 in plasma cholesteryl esters (CE) (r = -0.23) and TG (r = -0.29), and positively with the total percentage of saturated fatty acids in platelets (r = 0.33), but had no significant correlations with any of the ω6-fatty acids. Thrombin-induced aggregation correlated negatively with the ω3/6ω ratio in adipose tissue (r = -0.25) and the 20: 3ω6/20: 4ω 6 ratio in plasma CE (r = -0.27) and free fatty acids (FFA) (r = -0.23), and positively with adipose tissue 18:2 (r = 0.23) and 20:4ω6 (r = 0.22) in plasma phospholipids (PL).The percentages of prostanoid precursors in platelet lipids, i. e. 20: 3ω 6, 20: 4ω 6 and 20 :5ω 3, correlated best with the same fatty acids in plasma CE (r = 0.32 - 0.77) and PL (r = 0.28 - 0.74). Platelet 20: 5ω 3 had highly significant negative correlations with the percentage of 18:2 in adipose tissue and all plasma lipid fractions (r = -0.35 - -0.44).These results suggest that, among a free-living population, relatively small changes in the fatty acid composition of plasma and platelets may be reflected in significant differences in platelet aggregation, and that an increase in linoleate-rich vegetable fat in the diet may not affect platelet function favourably unless it is accompanied by an adequate supply of ω3 fatty acids.

Sign in / Sign up

Export Citation Format

Share Document