Pair Of Ostia Research Articles

The hemolymph vascular system in Cupiennius salei (Araneae: Ctenidae)

In terms of physiology and behavior, Cupiennius salei is one of the best-investigated spider species. However, parts of its anatomy have only been described superficially to date. In the course of a comparative survey of the hemolymph vascular system in Araneae we therefore investigated C. salei using several injection methods in combination with semi-thin sections and micro computer tomography (MicroCT). Like all other Arthropoda, C. salei possesses an open circulatory system. A tubular heart is suspended dorsally in the opisthosoma via a number of ligaments. It is equipped with three pairs of ostia, and three pairs of cardiac arteries. The heart is surrounded by a pericardial sinus in which we were able for the first time to describe an intra-pericardial membrane. Anteriorly, the heart is extended by an anterior aorta which runs through the pedicel and divides into two branches within the prosoma. Arteries emanating from the branches of the aorta supply the prosomal appendages and the central nervous system. The subesophageal ganglion is supplied by numerous fine vessels which emanate from the transganglionic arteries and form tight loops. A network of capillaries, i.e. interconnections between afferent and efferent vessels, is here demonstrated for the first time to exist in the central nervous system of chelicerates. Data are compared with existing literature on the morphology of the circulatory system in Araneae and discussed with regard to the extension of the respiratory system and the varying lifestyles of different spiders.

Drosophilaflies combine periodic heartbeat reversal with a circulation in the anterior body mediated by a newly discovered anterior pair of ostial valves and `venous' channels

Heartbeat activity in tethered adult drosophilids was recorded using a linear optosensor chip and an IR-light beam. Recording from two to five sensor elements within 250 mum along the anterior heart, it was possible to analyze periodic reversals. In intact Drosophila melanogaster and D. hydei, longer anterograde pulse periods with lower pulse rates generally alternated with shorter retrograde pulse periods having higher pulse rates. These differences are dependent on heart anatomy: a newly discovered first pair of ostia is connected to bilateral thoraco-abdominal hemolymph channels. These channels are part of a venous space separated from the abdominal hemocoel by a septum, consisting of a metanotal ridge and the pericardial diaphragm lined by a special form of fat body. The channels are sealed, and their lumen is possibly controlled by the metathoracic tergo-pleural muscle. During retrograde pulses, the heart chamber works like a suction pump, aspiring hemolymph through the first ostia from the venous channels and discharging it through a newly described caudal opening. During forward beating, the anterior chamber receives hemolymph via all inflow ostia from the entire heart and drives it like a pressure pump through the narrow aorta. Also, during forward pulses, a lateral circulation occurs in the thorax as a result of the venous supply. Inhibition of abdominal mobility leads to an irregular heart rate, with pulse-wise alternating heartbeat reversals. The possible involvement of slow abdominal movements in heartbeat periodicity is discussed. The heartbeat periods are superimposed with intermittent bouts of abdominal pumping movements.

Evolutionary derivation of the American lobster cardiovascular system: an hypothesis based on morphological and physiological evidence

The cardiovascular system of the American lobster includes a large muscular heart that pumps blood into seven arteries, each of which ramifies extensively. Portions of the system may be viewed as relatively primitive, while others are highly derived. We have confirmed earlier findings that the sternal artery is not a single vessel, but a paired structure. The sternal artery and its partner closely resemble the medial branches of the segmental lateral vessels from the dorsal abdominal artery in anterior segments of the abdomen, and they may be homologous. We report that the walls of the dorsal abdominal artery contain blocks of striated muscle cells and that the artery can be induced to contract in response to electrical stimulation or perfusion with proctolin. These observations provide the basis for an attempt to trace the evolution of the heart and arteries from that of primitive malacostracans to its state of development in lobsters. Additional key words: Crustacea, Homarus americanus, evolution, heart, dorsal abdominal artery, sternal artery We present here anatomical and physiological evidence supporting the hypothesis that the cardiovascular system in adult decapod crustaceans, as illustrated for Homarus americanus (e.g., McLaughlin 1983), is derived, by migration and regional specialization, from the evolutionarily primitive plan of a dorsal, longitudinal, tubular, muscular heart with a pair of ostia in each segment running from the head to the telson (Siewing 1963; Hessler et al. 1982). It has been postulated, based on the Cephalocarida, that crustacean ancestors displayed strong serial homology in body plan (Sanders 1955), possibly arising from annelid ancestral antecedants such as an extended nauplius-like larva (Hessler et al. 1982). The Cephalocarida and Branchiopoda (Anostraca, fairy shrimps) are closest to this prototype. This primitive plan is still the general plan in stomatopods (Siewing 1963; McLaughlin 1980). In the ancestral plan, the heart tube lies immediately dorsal to the gut and extends the entire length of the body. The heart tube supplies hemolymph to a short non-muscular anterior median artery to the brain, to some form of serially homologous segmental lateral arterial supply in each body segment, and to an unpaired posterior artery to the telson. The segmental a Author with whom to correspond. lateral arteries are short and do not branch extensively. Paired ostia admit returning hemolymph to the heart tube in each segment. In adults of H. americanus, the single-chambered heart is suspended in the pericardial sinus in the dorsal thorax by several pairs of alary ligaments (Lochhead 1950, pp. 428-431; McLaughlin 1980, pp. 138-141). These elastic ligaments are stretched during systole, and they expand the heart during diastole. During diastole, the heart passively fills with hemolymph from the pericardial sinus through three pairs of muscular,

Evolutionary Derivation of the American Lobster Cardiovascular System: An Hypothesis Based on Morphological and Physiological Evidence

The cardiovascular system of the American lobster includes a large muscular heart that pumps blood into seven arteries, each of which ramifies extensively. Portions of the system may be viewed as relatively primitive, while others are highly derived. We have confirmed earlier findings that the sternal artery is not a single vessel, but a paired structure. The sternal artery and its partner closely resemble the medial branches of the segmental lateral vessels from the dorsal abdominal artery in anterior segments of the abdomen, and they may be homologous. We report that the walls of the dorsal abdominal artery contain blocks of striated muscle cells and that the artery can be induced to contract in response to electrical stimulation or perfusion with proctolin. These observations provide the basis for an attempt to trace the evolution of the heart and arteries from that of primitive malacostracans to its state of development in lobsters. Additional key words: Crustacea, Homarus americanus, evolution, heart, dorsal abdominal artery, sternal artery We present here anatomical and physiological evidence supporting the hypothesis that the cardiovascular system in adult decapod crustaceans, as illustrated for Homarus americanus (e.g., McLaughlin 1983), is derived, by migration and regional specialization, from the evolutionarily primitive plan of a dorsal, longitudinal, tubular, muscular heart with a pair of ostia in each segment running from the head to the telson (Siewing 1963; Hessler et al. 1982). It has been postulated, based on the Cephalocarida, that crustacean ancestors displayed strong serial homology in body plan (Sanders 1955), possibly arising from annelid ancestral antecedants such as an extended nauplius-like larva (Hessler et al. 1982). The Cephalocarida and Branchiopoda (Anostraca, fairy shrimps) are closest to this prototype. This primitive plan is still the general plan in stomatopods (Siewing 1963; McLaughlin 1980). In the ancestral plan, the heart tube lies immediately dorsal to the gut and extends the entire length of the body. The heart tube supplies hemolymph to a short non-muscular anterior median artery to the brain, to some form of serially homologous segmental lateral arterial supply in each body segment, and to an unpaired posterior artery to the telson. The segmental a Author with whom to correspond. lateral arteries are short and do not branch extensively. Paired ostia admit returning hemolymph to the heart tube in each segment. In adults of H. americanus, the single-chambered heart is suspended in the pericardial sinus in the dorsal thorax by several pairs of alary ligaments (Lochhead 1950, pp. 428-431; McLaughlin 1980, pp. 138-141). These elastic ligaments are stretched during systole, and they expand the heart during diastole. During diastole, the heart passively fills with hemolymph from the pericardial sinus through three pairs of muscular,

Scanning electron microscopy of the dorsal vessel of Panstrongylus megistus (Burmeister, 1835) (Hemiptera: Reduviidae)

In this study we analyzed the microanatomy of the dorsal vessel of the triatomine Panstrongylus megistus. The organ is a tubule anatomically divided into an anterior aorta and a posterior heart, connected to the body wall through 8 pairs of alary muscles. The heart is divided in 3 chambers by means of 2 pairs of cardiac valves. A pair of ostia can be observed in the lateral wall of each chamber. A bundle of nerve fibers was found outside the organ, running dorsally along its major axis. A group of longitudinal muscular fibers was found in the ventral portion of the vessel. The vessel was found to be lined both internally and externally by pericardial cells covered by a thin laminar membrane. Inside the vessel the pericardial cells were disposed in layers and on the outside they formed clusters or rows.

Anatomy and histology of Embolyntha batesi MacLahlan, 1877 (Embiidina)

The Embioptera are rather generalized insects whose internal anatomy is simple and not subject to great modifications. For this reason these insects form an ideal group for elementary anatomical and histological studies (fig. 2). The digestive tract is a long, simple tube without convolutions or diverticulae from the buccal cavity to the rectum. The buccal structures are of the chewing type. The oesophagus and ingluvia are differentiated only by slight dilation of their walls. In nymphs and females the proventriculus is very distinct due to folds which flatten as the structure becomes packed with food. The enteron is the largest in such forms and in both sexes limited caudally by the Malpighian tubules. The proctodeus has six large rectal papillae. The nervous system is complete with only the fifth abdominal segment lacking a ganglion in the metathorax includes the ganglion of the first abdominal segment. The brain exhibits very clear structure in histological sections. The tracheal system includes two pairs of thoracic spiracles and eight abdominal pairs. Only th metathoracic spiracle has an air expiration function; all others serve for inspiration. Various structures in the spiracles protect the atrium. The circulatory system includes a long, simple dorsal vessel which extends forward from the ninth abdominal segment into the cranium. It opens anteriorly near the circumoesophageal connectives. The dorsal vessel has a pair of ostia and valves corresponding to each abdominal and thoracic segment. It lacks the diverticulae or folds commonly found in more highly evolved insects. The excretory system is represented by Malphighian tubules, pericardial cells, and fat-body. The number and disposition of Malpighian tubules is variable within the order. The pericardial cells are localized around the entire dorsal vessel up to the opening of the aorta in the head. The fat-bodies form compact layers in the dorsal and ventral regions of the body. In males they are more developed in the abdominal region. The mandibles, maxillae, and salivary glands are of a simple type with very few cytological modifications. Only the salivary glands which extend into the mesothoracic region show appreciable specialization. The reproductive system is bi-sixual and shows considerable sexual dimorphism. Males have five pair of testes with a metameric disposition, two distinct ducts, two epidymis, and the ejaculatory organs. The accessory glands vary in number and size and open in the anterior portion of the ejaculatory duct. The female reproductive organs are of the panoistic type. The system includes five pairs of ovarioles, two long paired oviducts a small, unpaired oviduct and the spermatheca which opens in the vagina. Reproduction usually involves a union of male and female gametes, and eggs are usually laid in clusters attached to a substrate.

II.—The Circulatory System of the Crustacean Euphausid, Meganyctiphanes norvegica (M. Sars)

SynopsisIn Meganyctiphanes the blood is pumped from the heart to the various regions of the body by way of a well-developed arterial system. It passes out of the open ends of the final sub-branches of the arteries into the various sinuses, finally collecting in the posterior ventral region of the thorax. From there, by the action of the pericardium and the muscles associated with the afferent branchial channels, it enters the afferent branchial channels whence it circulates through the branchial veins in the branchiæ, to the efferent branchial channels. The beating of the heart draws the blood into the pericardium whence it reaches the heart cavity by way of two pairs of ostia.

On the Life History and Structure of the Early Stages of Simuliidae (Diptera, Nematocera). Part II

(A) Life History.(1)Simulium larvaeare found in streams where the current is very fast. They are sedentary in habit and fix themselves to some support by means of their posterior sucker and sticky salivary secretion.(2) Progression is achieved by looping movements which have been described in detail.(3) Larvae feed on all kinds of fresh water animalcules, and algae.(4) Two species were reared from eggs to the adult flies for the first time in the laboratory. Abundance of food and aeration of water are two very important factors governing the rearing of these larvae.(5) There are six larval stages, each stage lasting 4–7 days. The gradual changes in the successive stages are described inS. erythrocephalumandS. aureum.(6) The sixth-stage larva, having woven its cocoon, changes into a pupa, the whole process, weaving of cocoon and pupation (described in detail), takes 75–90 minutes. Pupal life lasts 5–15 days, depending on temperature.(7) The eggs are sub-triangular in form and are laid in large patches on aquatic plants below the surface of water.(8) The first-stage larva is characterised by the presence of an egg-burster situated dorsally upon the head.(B) Morphology.(9) The larvae are eucephalous, with eleven faintly marked body-segments, three thoracic and eight abdominal, the eighth abdominal being apparently divided into two parts, the posterior carrying the anus and posterior sucker. There is a median uniramous thoracic proleg which like the posterior sucker is provided with a number of cuticular hooks.(10) The head has a number of markings which are of great taxonomic importance.(11) The head-appendages are: A pair of jointed antennae, a rounded labrum, a pair of lateral fan-shaped appendages (the premandibular organs), a pair of mandibles, a pair of maxillae each with a single-jointed palp, a hypopharynx, and a labium. These appendages have been described in detail in this paper for the first time.(12) The alimentary canal, malpighian tubules, salivary glands, muscular system and gonads are dealt with in detail.(13) The oesophageal valve has no blood sinus as has been erroneously described by previous writers.(14) A pair of dorsal glands are present above the pharynx. Their walls consist of large uninuclear cells. Dorsal glands have so far been found only inSciaraamong Dipterous larvae.(15) There is a well-developed central as well as visceral nervous system. The bilobed brain lies in the head and a chain of eleven ganglia in the body. Both the supra-intestinal and the infra-intestinal visceral systems are fully worked out for the first time.(16) There is a well-developed tracheal system with ten closed spiracles, one prothoracic, one metathoracic and eight abdominal.(17) The flattened dorsal vessel stretches from the seventh abdominal segment to the head where it ends just behind the brain. It is dilated in the seventh segment to form the heart which is provided with two pairs of ostia.(18) Nephrocytes or excretory cells (pericardial, and peri-oesophageal) are described for the first time and compared to similar structures in other Dipterous larvae.(19) A detailed description of the early stages of all the known (seventeen)1British species is given, with remarks about eleven of them, as they occur in Sweden, Norway and France.(20) The characters used for determining the species are as follows:Larva. Head markings; antennae; mandibles; submentum; anal gills; ventral papillae; and posterior sucker.Pupa. Chaetotaxy, Respiratory filaments, and Cocoon.

On the Life History and the Anatomy of the Early Stages ofForcipomyia(Diptera, Nemat., Ceratopogoninae)

(1)Forcipomyiais one of the few genera of the Ceratopogoninae (Chironomidae) whose larvae are not aquatic. They retain, however, the apneustic condition typical of the entire family, and are therefore compelled to live in moist places such as beneath the rotting bark of fallen trees, in the hollow tap roots of dead plants, in wounds and rot holes in trees, in drying horse and cow manure, in decaying fungi, and in the nests of ants. The immature forms are strongly gregarious.(2) The larvae pass through four stages, each lasting about a week; the successive changes in chaetotaxy at each moult is recorded in the discussion ofF. picea. All known European species of this genus hibernate as third or fourth stage larvae. The duration of the pupal stage is about one week; the length of life of the adult has not been determined. There are usually three generations per annum. The adults are known to suck the blood of other insects.(3) The larvae are eucephalous, more or less cylindrical, 3–6 mm. long, with eleven clearly denned segments (three thoracic and eight abdominal, the eighth divided into two apparent segments). Progression is achieved by means of a retractable, biramous,prothoracic pseudopod, and a ventral hook-studded ridge on the ultimate abdominal segment, with the occasional aid of the mandibles.(4) The head and body bear numerous lanceolate and simple hairs of great specific importance.(5) The mouth-parts consist of a fleshylabrum, a pair of smallpremandibles, a pair of long, slendermandiblesworking in the sagittal plane on either side of the labrum, a pair of reducedmaxillaeof fleshy nature with chitinous internal supports, and a simple untoothedlabium. Within the head there is a complicated chitinous structure, thehypopharynx; this is figured and described in full detail and its action in comminuting the food is revealed for the first time.(6) No investigation has hitherto been made of the internal anatomy. Thealimentary canal, consisting of buccal cavity, hypopharynx, oesophagus, mid-gut, and hind-gut, is quite simple in structure, without nodules or caecal chambers. It is only slightly longer than the body, a loop occurring in the hind-gut when the larva contracts.(7) Themalpighian tubulesare either two or three in number, the latter condition being unique among insects. The third is ventral, passing into the posterior part of the body only.(8) Thesalivary glandsare a pair of S-shaped bodies closely adhering to the walls of the anterior portion of the mid-gut; they are chiefly composed of large binucleate cells.(9) Thecirculatory systemconsists of a dorsal vessel extending throughout the body and passing between the lobes of the brain above the oesophagus into the head. In the eighth abdominal segment it enlarges slightly to form the heart, with one pair of ostia or valves situated on its posterior extremity.(10) Thenephrocytesare arranged segmentally, four to each abdominal segment and a single mass in the thorax, all attached to the dorsal vessel. The excretory function of these cells was demonstrated by injection of ammonia-carmine into the body cavity.(11) Thenervous systemis only very slightly cephalised, there being seven ganglia for the eight abdominal segments and three in the thorax; the normal bilobed brain is situated in the thorax in all larval stages. Thesympathetic systemis described, and differs somewhat from that of its close relative,Chironomus.(12) Despite the absence of spiracles there is a well-developedtracheal systemin the form of two main trunks with transverse connections, branch tracheae, and subcutaneous plexuses.(13) Themuscular system, oenocytes, fat-body, andgonadshave also been studied in detail.(14) The larval skin is retained upon the last four or five abdominal segments of thepupa.(15) The characters used for determining the species, in their order of importance, are as follows:Larva: chaetotaxy, prothoracic pseudopod, markings of the head, anal blood-gills.Pupa: cuticular spines, prothoracic horns.(16) The larvae and pupae of nine species ofForcipomyiaare described with particular reference to their specific characters. Descriptions of the adults of two new species,F. radidcolaandF. pulchrithorax, by Mr F. W. Edwards, are appended.(17) Closely related forms areEuforcipomyiaand other exotic subgenera not yet named, and the genusAtrichopogon(now includingKempia). Dasyhelea belongs to this group of hairy-winged flies, but its larvae partly resemble those of the bare-winged Ceratopogonines in that they have lost the pro-thoracic pseudopod and macrochaetae, but retain the anal hooks.