Respiratory water flow and production of mucus in the cushion star, Pteraster tesselatus Ives (Echinodermata: Asteroidea)

Histological analysis revealed three types of mucous cells present in the tissues of Pteraster tesselatus Ives. They were all unicellular in structure and each was restricted to certain areas of the anatomy. Mucus produced by these gland cells was forced out onto the aboral surface of Pteraster by water pressure generated within the nidamental cavity (respiratory chamber).Water flow in and out of the respiratory chamber was powered both by muscle contractions and a complex network of overlapping ossicles. Ambient sea water was allowed into the respiratory chamber only through large pores lining the ambulacral groove. Expulsion of respiratory water out of the chamber was by either one of two different pathways. In defence, water and secreted mucus were forced out of the numerous spiracular openings that perforate the supradorsal membrane. When, on the other hand, the sea star was not in a defensive posture, water was simply passed out through the centrally located osculum.     

Btk-dependent epithelial cell rearrangements contribute to the invagination of nearby tubular structures in the posterior spiracles of Drosophila

The Drosophila respiratory system consists of two connected organs, the tracheae and the spiracles. Together they ensure the efficient delivery of air-borne oxygen to all tissues. The posterior spiracles consist internally of the spiracular chamber, an invaginated tube with filtering properties that connects the main tracheal branch to the environment, and externally of the stigmatophore, an extensible epidermal structure that covers the spiracular chamber. The primordia of both components are first specified in the plane of the epidermis and subsequently the spiracular chamber is internalized through the process of invagination accompanied by apical cell constriction. It has become clear that invagination processes do not always or only rely on apical constriction. We show here that in mutants for the src-like kinase Btk29A spiracle cells constrict apically but do not complete invagination, giving rise to shorter spiracular chambers. This defect can be rescued by using different GAL4 drivers to express Btk29A throughout the ectoderm, in cells of posterior segments only, or in the stigmatophore pointing to a non cell-autonomous role for Btk29A. Our analysis suggests that complete invagination of the spiracular chamber requires Btk29A-dependent planar cell rearrangements of adjacent non-invaginating cells of the stigmatophore. These results highlight the complex physical interactions that take place among organ components during morphogenesis, which contribute to their final form and function.     

Scanning electron microscopy of the posterior spiracles of cattle grubs Hypoderma bovis and Hypoderma lineatum

Posterior spiracles of newly hatched first instar larvae of Hypoderma bovis (L.) and H. lineatum (DeVill.) consist of two pairs of spiracular openings. Each pair is surrounded by a rima bearing three spines. Posterior spiracles of second instar larvae are composed of a pair of medial ecdysial scars bounded laterally by spiracular plates. H. bovis spiracular plates have twenty-nine to forty openings, each surrounded by a slightly raised rima. H. lineatum spiracular plates have eighteen to twenty-five openings. Spiracular openings lead to posterior felt chambers which are connected to a common anterior felt chamber filled with a meshlike network. In third instar H. bovis each medial ecdysial scar is surrounded by a strongly concave spiracular plate. Spiracular openings are surrounded by slightly raised rima. Most rimae bear a spine. Spiracular plates of H. lineatum are flat and rimae are without spines. Each spiracular opening leads to a posterior felt chamber, several of which are confluent with a larger anterior felt chamber. Anterior felt chambers open into the dorsal longitudinal tracheal trunk. Felt chambers in third instar larvae are also filled with a complex mesh.     

Respiratory significance of the external morphology of adults and fifth instar nymphs of Notonecta undulata Say (Aquatic Heteroptera; Notonectidae)

The bodies of adult and fifth instar Notonecta possess external air stores which are periodically renewed at the surface of the water. Both nymphs and adults have large ventral air stores on the thorax and abdomen and obtain atmospheric air at the posterior end of the latter; the adult also has dorsal subalar and supra-alar air stores on both these regions. Ten pairs of spiracles open onto the air stores. Although the seven small, ventrally placed abdominal spiracles are probably both exhalant and inhalant in nymphs and adults, the three large anterior spiracles (mesothoracic, metathoracic, and first abdominal), which play a more important respiratory role, appear to function differently in mature and immature Notonecta. In the nymph they are probably both inhalant and exhalant, and communicate broadly with each other and with the ventral air stores. In the adult, however, they open onto separate, air-filled chambers, each of which communicates differently with various parts of the air stores. Although all three probably function in exhalation, only the first abdominal spiracle, whose spiracular chamber is widely continuous with the dorsal and ventral air stores, appears to be well suited for inhalation. Several morphological features, most notably the development of long prothoracic lobes, separate spiracular chambers, and long, movable forewings, allow the adult a greater variety of respiratory modes than are available to the nymph. Some of the respiratory advantages of the adult are: (1) a larger amount of stored air; (2) a longer subalar air store, which can serve as an alternate pathway between the air stores and the atmosphere; (3) a greater capacity to utilize dissolved as well as atmospheric oxygen; (4) greater separation and functional specialization of the three anterior spiracles, thus allowing more separation of exhaled air from oxygen-rich air on the external surface of the thorax; (5) the probable ability to regulate the continuity between various parts of the air stores, thus utilizing alternate pathways of air circulation and/or changing the functions of the three anterior spiracles; and (6) better protection of the latter against the entry of water during prolonged submergence.     

The structure of the gas bladder of the spotted gar,Lepisosteus oculatus

We report here on the macroscopic, light microscopic, and electron microscopic structure of the gas bladder (GB) of the spotted gar, Lepisosteus oculatus. The GB opens into the pharynx, dorsal to the opening of the oesophagus, through a longitudinal slit bordered by two glottal ridges. Caudal to the ridges, the GB is an elongated sac divided into a central duct and right and left lobes. The lobes are formed by a cranio‐caudal sequence of large air spaces that open into the central duct. The structure of the GB is that of a membranous sac supported by a system of septa arising from the walls of a central duct. The septa contain variable amounts of striated and smooth muscle might function to maintain the bladder shape and in providing contractile capabilities. The presence of muscle cells, nerves, and neuroepithelial cells in the wall of the GB strongly suggests that GB function is tightly regulated. The central duct and the apical surface of the thickest septa are covered by mucociliated epithelium. Most of the rest of the inner bladder surface is covered by a respiratory epithelium which contains goblet cells and a single type of pneumocyte. These two cell types produce surfactant. The respiratory barrier contains thick areas with fibrillar material and cell prolongations, and thin areas that only contain basement membrane material between the capillary wall and the respiratory epithelium. Lungs and GBs share many anatomical and histological features. There appears to be no clear criterion for structural distinction between these two types of respiratory organs. J. Morphol. 276:90–101, 2015. © 2014 Wiley Periodicals, Inc.     

Transitions in insect respiratory patterns are controlled by changes in metabolic rate

We examined the respiratory patterns of Rhodnius prolixus and Gromphadorhina portentosa as metabolic rates varied with temperature to determine whether insects transition from discontinuous (DGC), cyclical and continuous respiration as a response to increasing aerobic demand. Using flow through respirometry we: (1) determined the effects of temperature on metabolic rate; (2) objectively defined periods of spiracular closure; (3) observed whether there was a correlation between metabolic rate and length of spiracular closure. At low temperatures both species exhibit lengthy periods of spiracular closure reflecting a discontinuous respiratory pattern. As metabolic rate increased, periods of spiracular closure decreased and insects displayed a more cyclical pattern of respiration. As metabolic rates increased even further under the highest experimental temperatures, periods of spiracular closure decreased even more and a continuous respiratory pattern was employed by both species. Our results suggest that the three described respiratory patterns in insects are not distinct but are instead a continuum of respiratory responses driven by the metabolic demand experienced by the insect.     

Ventilatory structures in Cryphocricos barozzii Signoret (Heteroptera, Naucoroidea)

Plastron and spiracular features strongly resemble those of Aphelocheirus aestivalis (Fab.), described by Messner et al. (1981). Plastronal foliose hairs, somewhat irregular shaped are regularly distributed in the plastron. Very numerous tiny openigs on sternites an tergites connect platronal air with a subcuticular air film limited internally apparently by a membrane. Aplicated, radial, structure at the proximal end of the tracheae, almost occluding the extremely fine spiracular openings, appear with lesser variations in both species, suggesting close relationships than accepted until now.     

Scanning and transmission electron microscopy of oral sucker papillae of Philophthalmus megalurus

Edwards H. H., Nollen P. M. &; Nadakavukaren M. J. 1977. Scanning and transmission electron microscopy of the oral sucker papillae of Philophthalmus megalurus. International Journal for Parasitology7: 429–437. Scanning electron microscopy reveals papillae on both the inside and outside of the oral sucker of the eyefluke, Philophthalmus megalurus. In the transmission electron microscope the papillae can be divided into 3 different types with 2 of these types occurring on the outside of the oral sucker. One type of outer papilla contains a bulb cell which is terminated by a cilium having an apparent typical arrangement of microtubules. This type is a presumed sensory receptor having tango- and/or rheoreceptor function. The second type of outer papilla contains a gland cell which secretes electron-dense granules to the outside of the fluke. The third type of papilla is found only on the inside of the oral sucker and contains a bulb cell terminated by a cilium which does not have the typical 9 + 2 arrangement of microtubules. Instead, their numbers increase to over 60 randomly arranged microtubules. This inner papilla is felt to have chemoreceptor function because of its location and the presence of the modified cilium. The bulb cell of the inner papilla contains 2 newly described features. The first is granular, and associated with microtubules; it may be a possible nucleating site for microtubule synthesis. The second structure is a crystalline inclusion of unknown function and origin.     

Le genre Murciella (Foraminifère, Rhapydionininae), dans le Crétacé supérieur de Grèce (zone de Gavrovo-Tripolitza)

Several new species are described, of which theendoskeletal features present strong similarities with YaberinellaVaughan. Each chamber consists of: 1) a single peripheral layer of tubular «primary chamberlets perpendicular to the septa they join, 2) concentric inner layers of tubular «secondary chamberlets oriented obliquely to the preceding, each layer inclined in the contrary sense to its inner and outer neighbour, and the inclination being symmetrical with respect to any radial plane. Thus the secondary chamberlets form two helices, each with the same axis, which is also the axis of the chamber and the axis of growth: this is called «helicoidal structure. Lateral connections exists between the tubes of different layers («stolons).The chamber arrangement, and above all the presence of a preseptal space equipped with buttresses exclude the new species from Yaberinella and permits their assignment to the sub-family Rhapydionininae, more precisely to the genus MurciellaFourcade, of which several known sections (particularly the holotype of the type-species) seem to show the same organisation.The mode of coiling shown by some of the new forms, together with the lateral connection between chamberlets (the function of which might be the same as that of the preseptal space) permit the advocation of a development from Murciella (Tethysian, Upper Cretaceous) to Yaberinella (central American, Eocene).     

Neural control of homologous behaviour patterns in two blaberid cockroaches

Activity patterns of motoneurones which innervate spiracular muscles in two blaberid cockroaches, Blaberus discoidalis and Gromphadorhina portentosa, have been monitored during two homologous behaviour patterns: respiratory and non-respiratory tracheal ventilation. Based upon the activity of spiracular motoneurones during these two activities, the abdominal spiracles have been divided into three functional groups: vestigial, respiratory and non-respiratory. In Blaberus discoidalis spiracle 3 is vestigial, spiracles 6, 7, 8 and 10 are respiratory, and spiracles 4, 5 and 9 are non-respiratory. In Gromphadorhina portentosa spiracles 3 and 10 are vestigial, spiracle 4 is non-respiratory and spiracles 5–9 are respiratory.Respiratory spiracles in both species are characterized by activity patterns of their motoneurones during respiratory tracheal ventilation: low frequency firing at irregular intervals during the respiratory pause and a higher frequency burst synchronous with the expiratory abdominal compression. Non-respiratory spiracles are characterized by complete inactivity of their opener motoneurones during respiratory tracheal ventilation. These motoneurones are activated by mechanical stimulation in both species, which simultaneously suppresses activity in respiratory opener motoneurones. In Blaberus discoidalis, there are no differences between activity patterns of respiratory and non-respiratory closer motoneurones. In Gromphadorhina portentosa, not only do respiratory and non-respiratory closer motoneurones have different activity patterns, but the activity pattern of respiratory closer motoneurones is different during respiratory and non-respiratory tracheal ventilation. The functional implications of these several spiracular motoneurone activity patterns are discussed.     

Functional micromorphology of petals of <Emphasis Type="Italic">Chaenomeles japonica</Emphasis> exposed to humid and cold season

In this study, micro- and nano-traits of petal epidermises of flowers of Chaenomeles japonica extended under environmental conditions, during the humid and cold period of the year, are presented. The outer (abaxial) and the inner (adaxial) epidermises of petals of C. japonica consist of convex and papillae cells, respectively, that are covered by epicuticular wrinkled relief further ornamented by submicron motifs, forming interfaces between floral tissues and environment. Structural epidermal features of the petal relief at the nanoscale level reveal different functionality on the two sides of the corolla. The cuticular folds of convex epidermal cells display declining water retention on the outer petal surface and the exposed side of the corolla to the environmental conditions. The cuticular folds of papillae epidermal cells increase in size the inner petal surface, in comparison with the outer surface; such traits facilitate light absorption and enhanced the contact area among folds and curvatures at the inner side of the corolla. It appears that nanometric surface structures of petals may be important adaptive features of C. japonica flowers, contributing to their performance in the field.     

The cerebral ganglia of Milnesium tardigradum Doyère (Apochela, Tardigrada): Three dimensional reconstruction and notes on their ultrastructure

Differential interference contrast micrographs from stretched animals, serially sectioned semi-thin and ultrathin sections revealed that the cerebral ganglia (supraoesophageal mass) of the eulardigrade Milnesium tardigradum lie above the buccal tube and adjacent tissue like a saddle. It has an anterior indentation which is penetrated by two muscles that arise from the cuticle of the forehead. The cerebral ganglia consist of lateral outer lobes bearing an eye on each side, and two inner lobes which extend caudally. Between the inner lobes a cone-like projection tapers into a nerve bundle. Each outer lobe is joined with the first ventral ganglion. From the outer lobe near the eye the ganglion for a posterolateral sensory field extends to the epidermis. Anterior to the supraoesophageal mass are three dorsal ganglia for the upper three peribuccal papillae. Two additional ganglia attached to the cerebral mass supply the lateral cephalic papillae. The cerebral ganglia are covered by a thin neural lamella. The pericarya which surround the neuropil have large nuclei. Near the axons in the centre of the supraoesophageal mass the cytoplasm is crowded with vesicles of different size and appearance. Some of them resemble synaptic vesicles while others resemble dense core bodies. Structurally different types of synapses and axons can be distinguished within the neuropil.     

Fine Structure of Cephalic Sense Organs in Heterodera glycines Males

Cephalic sense organs of Heterodera glycines males were examined in detail by electron microscopy. Each amphid basically consists of an amphidial gland, a nerve bundle, and an amphidial duct. The amphidial gland consists of a microvillous region, and laterally is closely associated with a large secretory cell. The nerve bundle penetrates the microvillous region, and further anteriorly individual nerve processes (dendrites) separate from one another, thus forming a sensilla pouch which is enveloped by the microvillous region of the gland. Anterior to the pouch, the cilia-like dendrites converge as they enter and eventually terminate in the amphidial duct. Heterodera glvcines males have the innervation basis for a full complement of sixteen papillae, although surface manifestations are present for only six minute inner labial papillae. In addition, four outer labial and four cephalic receptors terminate beneath the surface, and another two dendrite pairs end further posteriorly beneath the basal plate of the cephalic framework. Papillary receptors which terminate beneath the surface are probably mechanoreceptive, whereas inner labial papillae have pore-like openings to the exterior and may be chemoreceptive. Amphids and papillae of H. glycines are fundamentally similar to those of Meloidogyne incognita, although certain striking differences exist.     

Ultrastructural features of the salt gland of Tamarix aphylla L.

Summary The salt gland in Tamarix is a complex of eight cells composed of two inner, vacuolate, collecting cells and six outer, densely cytoplasmic, secretory cells. The secretory cells are completely enclosed by a cuticular layer except along part of the walls between the collecting cells and the inner secretory cell. This non-cuticularized wall region is termed the transfusion are (Ruhland, 1915) and numerous plasmodesmata connect the inner secretory cells with the collecting cells in this area. Plasmodesmata also connect the collecting cells with the adjacent mesophyll cells.There are numerous mitochondria in the secretory cells and in different glands they show wide variation in form. In some glands wall protuberances extend into the secretory cells forming a labyrinth-like structure; however, in other glands the protuberances are not extensively developed. Numerous small vacuoles are found in some glands and these generally are distributed around the periphery of the secretory cells in association with the wall protuberances. Further, an unusual structure or interfacial apparatus is located along the anticlinal walls of the inner secretory cells. The general structure of the gland including the cuticular encasement, connecting plasmodesmata, interfacial apparatus, and variations in mitochondria, vacuoles, and wall structures are discussed in relation to general glandular function.     

The structure of the postantennal organ in Onychiurus sp. (Insecta: Collembola) and its connection to the central nervous system

Summary The postantennal organ in Onychiurus (group armatus) is a sensory organ comprising one sensory cell, several enveloping cells and cuticular structures.The perikaryon of the sensory cell is located in the central nervous system and distally gives off a dendrite in which one inner and two outer segments are distinguishable. Two ciliary structures connect the outer dendritic segments with the inner segment. The outer segments divide repeatedly, basal to the cuticular structures, into small branches which end distally beneath the cuticular wall. The wall of the cuticular structures is very thin and is pierced by numerous funnel-shaped pores. The pores are filled with electron-dense material which forms a continuous sheath underneath the cuticle. This material encases the small dendritic branches and the processes of the enveloping cells which occupy the lumen of the cuticular structures. There are three types of enveloping cells: one inner, several outer and one basal. Their processes differ in the manner in which they envelop the various regions of the dendrite.At the beginning of moulting outer dendritic branches are not found within the cuticular structures of the organ. They may be assumed to retract inwardly. However, in the later stages, when the cuticle is fully formed, the outer dendritic segments appear to divide. It is assumed that the small dendritic branches reach their targets before ecdysis. The electrondense material which clogs the intermoult cuticular pores is absent until the final stages of the moulting cycle.Supported by a grant from the Deutscher Akademischer Austauschdienst.     

Scanning electron microscopy of the labia of Baylisascaris procyonis (Nematoda)

The labial organization of adult Baylisascaris procyonis was studied by scanning electron microscopy, and found to be similar for males and females. The apical part of each lip was smooth, and the basal part reticulated. The dorsal lip possessed two dorsolateral double papillae and two internal labial papillae; the two subventral lips each had one ventrolateral double and one externolateral papilla, two internal labial papillae, and an amphid. The small papilla of each double set was dome-shaped and smooth, whereas the large papilla was broad and had a prominent central pore. The externolateral papillae had raised, highly sculptured surfaces with numerous slits and creases present. Amphids resembled those of previously studied nematodes. The internal labial papillae consisted of pits. Denticles arose as a single row from the apical edge of the inner labial surface, were usually evenly spaced, and pyramidal or conoidal in shape. They were typically unicuspid, but bicuspid denticles were occasionally seen. Denticle shape and size varied between specimens and on each specimen. A pit was seen in the cuticle in the central region of the denticular row of all lips. Several of these findings represent new information concerning ascaridoid nematodes.     

A re-evaluation of morphological characters in European Gentianella section Gentianella (Gentianaceae)

Morphological traits were investigated in Gentianella section Gentianella by morphometrics and Scanning Electronic Microscopy (SEM). Variation in vegetative measures and in calyx, corolla, ovary, and gynophor was analyzed in populational samples and herbarium material. Special emphasis was given to micro-morphology and variation of papillae on the calyx using SEM. Three types of papillae on the calyx lobes were found: (A) short conical (G. amarella-group, G. insubrica, G. germanica); (B) long conical often curved (G. campestris, G. anisodonta, G. engadinsesis, and G. liburnica; (C) long cylindrical (G. aspera and G. pilosa). G. austriaca, G. caucasea, G. crispata, G. fatrae, and G. ramosa usually lack any papillae. Plants without and with short conical papillae were found in G. bulgarica and G. lutescens as well as in the intermediate taxa G. bohemica and G. stiriaca. The different types of papillae together with other calyx characters (sinus, shape and margin of lobe) are of high systematic importance and provide more stable characters than morphometric flower measures. Principal component and correlation analysis revealed a strong response of nearly all morphometric traits to the environmental variable altitude. Adaptive and historical causes of morphological variation as well as taxonomical consequences are discussed and a determination key is provided.     

Tradeoffs between metabolic rate and spiracular conductance in discontinuous gas exchange of Samia cynthia (Lepidoptera, Saturniidae)

The insect tracheal system is a unique respiratory system, designed for maximum oxygen delivery at high metabolic demands, e.g. during activity and at high ambient temperatures. Therefore, large safety margins are required for tracheal and spiracular conductance. Spiracles are the entry to the tracheal system and play an important role in controlling discontinuous gas exchange (DGC) between tracheal system and atmosphere in moth pupae. We investigated the effect of modulated metabolic rate (by changing ambient temperature) and modulated spiracular conductance (by blocking all except one spiracles) on gas exchange patterns in Samia pupae. Both, spiracle blocking and metabolic rates, affected respiratory behavior in Samia cynthia pupae. While animals showed discontinuous gas exchange cycles at lower temperatures with unblocked spiracles, the respiratory patterns were cyclic at higher temperatures, with partly blocked spiracles or a combination of these two factors. The threshold for the transition from a discontinuous (DGC) to a cyclic gas exchange (^cycGE) was significantly higher in animals with unblocked spiracles (18.7 nmol g⁻¹ min⁻¹ vs. 7.9 nmol g⁻¹ min⁻¹). These findings indicate an important influence of spiracle conductance on the DGC, which may occur mostly in insects showing high spiracular conductances and low metabolic rates.     

Untersuchungen zur Frühontogenie vonNautilus pompilius (Linné)

A series of initial shells ofNautilus pompilius was investigated for morphologic and isotopic evidence of the early ontogenetic development. Shell morphologic features, such as curvature of early shell, cancellate sculpture, suture and grouping of septa, as well as very early shell injuries, color banding and shell/egg dimensions, seem to indicate an interpretation of early ontogeny differing from that which is now generally accepted. The O¹⁸/O¹⁶ and C¹³/C¹² ratios in the early shell and septa of twoNautilus specimens are given. Changes in the carbon isotope content are tentatively correlated with the end of the embryonic period and with environmental changes. Variations in the oxygen isotope content are in part ascribed to migrations from warm to cooler water after a certain stage of development. The size of the body chamber of the young animals can be determined by comparison of the isotope contents in outer shell and septa. Existing ideas concerning early ontogeny ofNautilus are critically discussed.     

<Emphasis Type="Italic">Amphibiophilus mooiensis</Emphasis> n. sp. (Nematoda: Amphibiophilidae), a parasite of <Emphasis Type="Italic">Amietia delalandii</Emphasis> (Duméril &amp; Bibron) (Amphibia: Pyxicephalidae) from South Africa

Four species of the genus Amphibiophilus Skrjabin, 1916 from pyxycephalid frogs in southern and central Africa are currently recognised as valid. Several specimens of Amphibiophilus were found in material from the common river frog, Amietia delalandii (Duméril & Bibron) (Amphibia: Pyxicephalidae), collected in Potchefstroom (North-West Province, South Africa). These specimens clearly differ from all previously known species by the shape of the distal end of the spicule, the shape of the gubernaculum and the structure of the synlophe. They are, thus, considered as a new species, Amphibiophilus mooiensis. As all other species in the family Amphibiophilidae Durette-Desset & Chabaud, 1981, A. mooiensis n. sp. possesses a number of archaic characters, such as a buccal capsule with a well-developed dorsal oesophageal tooth, six inner labial papillae, six outer labial papillae and four cephalic papillae. Molecular data (cox1 and ITS-28S rDNA sequences) are provided and host and geographical specificity are discussed.