Fine structure of the sensilla of Peripatopsis moseleyi (Onychophora)

Summary Three types of sensilla occurring on the lips and on the antennae of Peripatopsis moseleyi have been investigated by scanning and transmission electron microscopy. On the lips sensory spines can be found which contain numerous cilia originating from bipolar receptor cells. They reach the tip of the spine where the cuticle is modified. The perikarya of the sensory cells, a large supporting cell with a complicated surface and a second type of receptor, form a bud-like structure and are surrounded by a layer of collagen fibrils. The second receptor cell bears apical stereocilia as well as a kinocilium which are directed towards the centre of the animal — thus the cell appears to be turned upside down. The sensilla of the antennae are 1) sensory bristles containing two or three kinds of receptor cells, one of which bears an apical cilium and one kind of supportive cell and 2) sensory bulbs located within furrows consisting of receptor cells with branched cilia and two kinds of supportive cells which are covered by a modified thin cuticle. According to the electron microscopical findings the sensory spines on the lips are presumably chemoreceptors. The sensory bristles on the antennae can be regarded as mechanoreceptors and the sensory bulbs as chemoreceptors.Supported by the Deutsche Forschungsgemeinschaft (Sto 75/3)     

Ultrastructure of introvert and pharynx of Halicryptus spinulosus (priapulida)

The introvert of Halicryptus spinulosus bears three kinds of sensilla: buccal papillae, ordinary scalids, and dentoscalids. They are all characterized by bipolar monociliary receptor cells. The former two have apical openings at which the sensory cilia are in close contact with the ambient sea water. The pharyngeal teeth are composed of slender epithelial cells the tips of which are devoid of organelles and a thick cuticle. The anatomy of the muscle arrangement of the pharynx is described. Glands occur at the junction of the pharynx and midgut.     

Lamellated outer dendritic segments of a chemoreceptor within wall-pore sensilla in the labial palp-pit organ of the butterfly,Pieris rapae L. (Insecta,Lepidoptera)

Summary The structure of the sensilla in the apical pit of the third segment of the labial palps in Pieris rapae was investigated in cryofixed and chemically fixed specimens. There is a field of about 80 club-shaped sensilla, 94% of which house a single sensory cell; 6% contain two sensory cells. All sensory cells are of the same type and are characterized by the structure of the dendritic outer segment. This consists of a proximal cylindrical and a distal lamellated section. The lamellae contain a lattice of longitudinally arranged microtubules. Filamentous strands connect the microtubules with the surface membrane of the lamellae. The surface area of the lamellated section amounts to about 40 m². Pores and pore tubules are present in the cuticular wall of the peg. Electrophysiological recordings show that the sensory cells are olfactory receptors, which react to a variety of complex plant odors and to the odor of conspecifics. It is shown that (a) the usual modality-specific characteristics of insect olfactory sensilla apply here also; (b) lamellation is not only a characteristic of thermoreceptors, but also of olfactory chemoreceptors; (c) there are pore tubules that are separated from the dendritic membranes by an extended dendritic sheath; and (d) in the labial palppit sensilla only the lamellated dendritic tip region may be involved in sensory transduction.Supported by the Deutsche Forschungsgemeinschaft (SFB 4/G1)     

Ultrastructure of the galeal sensory complex in adults of the Colorado potato beetle, Leptinotarsa decemlineata

ABSTRACT. The structure of galeal sensilla of the Colorado potato beetle, Leptinotarsa decemlineata Say (Coleoptera: Chrysomelidae), is described using electron microscopical methods. Previous electro-physiological studies indicate that these sensilla respond to amino acids, sucrose and plant saps. One physiological type is particularly sensitive to L-alanine and gamma amino butyric acid (GABA).
Three morphologically different types of sensilla occur on the galeal tip. The more numerous apical pegs are not distinguishable from one another on the basis of external structure, although they differ physiologically. Five sensory cells are associated with most apical pegs. One apical peg, the α-sensillum, contains only four cells. All apical pegs have one cell with a tubular body. The remaining cells have unbranched dendrites and are associated with a single apical pore.
Apical hairs differ from the apical pegs by having double innervation. Within the hair shaft, a dendritic sheath is lacking and the sensillar sinus extends to the base of the hair. The function of this hair type is not known.
Numerous mechanosensory hairs which surround the other sensilla are singly innervated and contain a tubular body at the level of the outer dendritic segments.     

Morphology of antennal sensilla of the brown spruce longhorn beetle,Tetropium fuscum (Fabr.) (Coleoptera: Cerambycidae)

The antennal sensilla of the brown spruce longhorn beetle, Tetropium fuscum (Fabr.) (Coleoptera: Cerambycidae) were examined with particular focus on the sensilla present on the apical flagellomere. T. fuscum antennae are composed of 11 segments, namely the scape, pedicel, and nine flagellomeres. Nine types of sensilla were observed: three types of sensilla chaetica, sensilla trichodea, two types of sensilla basiconica, grooved peg sensilla, thick-walled sensilla, and Böhm bristles. Seven of these types were present on the apical flagellomere, the exceptions were sensilla chaetica type 3 and Böhm bristles. There were no significant differences in the distribution or density of sensilla present on the ninth flagellomere of males and females, except that males had significantly more sensilla chaetica type 1, which are put forward as the putative contact chemoreceptors for T. fuscum.     

Fine structure of antennal mechanosensilla of adult Rhodnius prolixus stål (Hemiptera: Reduviidae)

Each antenna of both sexes of adult Rhodnius prolixus has approximately 570 mechanosensitive neurons that innervate five morphologic types of cuticular mechanosensilla: campaniform sensilla, tapered hairs, trichobothria, and type I and type II bristle sensilla. Each campaniform sensillum and tapered hair is presumably innervated by one mechanosensitive bipolar neuron and probably functions in proprioception. The campaniform sensilla being located at the base of the scape could monitor the position of the antenna. Tapered hairs are found at the distal margin of flagellar segment I and projecting laterally from the bases of the pedicel and scape. They probably provide information about the relative positions of the antennal segments. Seven trichobothrium are located on the pedicel and three on flagellar segment I. Each trichobothrium has a long filamentous hair inserted into the base of a socket that extends inwardly as a cuticular tube and is innervated by one bipolar neuron with a tublar body, a parallel arrangement of microtubules associated with electron-dense material. The trichobothria may respond to small variations in air currents. Type I bristles occur at the base of the antenna and are the most numerous type of mechanosensillum; an average of 452 occur on each antenna of females and 440 on males. The bristle is curved toward the antennal shaft and is serrated distally. Type II bristles are located distally and are the second most numerous type of mechanosensillum; an average of 88 were counted on each antenna of females and 94 on males. The type II bristle is straight with small, longitudinal, external grooves and projects laterally from the antennal shaft. Each type I and II bristle sensillum is innervated by a bipolar neuron whose dendrite is divided into an inner and outer segment. The outer segment is encased by a dendritic sheath which may be highly convoluted and distally contains a tubular body. Two sheath cells are associated with each sensillum. Both types of bristle sensilla have a tactile function. The tubular bodies of both types of bristle sensilla have a complex structure indicating that they are very sensitive. Variations in the amount and arrangement of the electron-dense material at the tip of the tubular bodies may reflect differences in viscoelastic properties that underlie functional characteristics.     

Labial tip sensilla of Blissus leucopterus leucopterus (Hemiptera: Blissidae): Ultrastructure and behavior

The cuticular sensory receptors that are found on the apex of the labium of hemipterans play an important role in their feeding behavior. In this study we describe the ultrastructure, number, and distribution of sensilla on the labium apex of the chinch bug, Blissus leucopterus leucopterus. Each apical field of sensilla on the labium contains 11 uniporous peg sensilla and one sensillum chaeticum. The uniporous peg sensilla are innervated by 4–5 bipolar neurons that send dendrites in the lumen of each peg. Three neurons are associated with each sensillum chaeticum, two neurons have dendrites in the lumen of the sensillum, and the third dendrite ends in a tubular body at the base of the sensillum. Behavioral tests that involve chemical blockage of the sensory receptors show the importance of the labial sensilla in feeding behavior. Both morphological and behavioral evidence indicate that the labial sensilla have a chemosensitive function.     

The structure of bimodal chemo-, thermo-, and hygroreceptive sensilla on the antenna of Locusta migratoria

Summary Coeloconic sensilla on the antenna of Locusta migratoria were investigated electrophysiologically, labeled and then examined under the scanning or transmission electron microscope. They can be categorized into two main morphological types: 1) sensilla with wall pores and two concentric cuticular walls (wp-dw sensilla), and 2) sensilla lacking wall pores (np-sensilla).Hygroreceptors were observed only in np-sensilla. Olfactory receptors were observed in wp-dw sensilla, but not in np-sensilla. Cold-sensitive units were found in both types. Wp-dw sensilla with a cold-sensitive unit also manifest a fatty acid olfactory receptor. This cold-sensitive unit appears to be less sensitive to drops in temperature than the cold receptor combined with hygroreceptors in np-sensilla. Recordings from both types revealed up to three or sometimes four units that could be distinguished on the basis of impulse amplitude.The number of np-sensilla on each antennal segment ranges from 0 to 6. These sensilla are pegs 4–5 m long with a terminal swelling. The dendritic outer segments of two sensory cells fit tightly into these pegs. The dendrite of the third sensory cell ends at its base. All three are up to 1 m thick, unbranched, and densely filled with microtubules. The cuticular wall and socket of the peg are characterized by (1) an electron-dense inner layer surrounding the dendrites and continuous with electron dense clusters at the base of the peg, and (2) clefts in the cuticle at the insertion of the peg.The present observations favor the hypothesis that insect sensilla combining the triad of moist air, dry air and cold receptors generally lack pores. Specifical, though still alternative roles in stimulus transduction can be suggested for substructures demonstrated in the present and previous electron microscopic investigations.Supported by the Deutsche Forschungsgemeinschaft (SFB 4:G1/D)     

Fine structural studies of the nervous system and the apical organ in the planula larva of the sea anemone Anthopleura elegantissima

The nervous system of the planula larva of Anthopleura elegantissima consists of an apical organ, one type of endodermal receptor cell, two types of ectodermal receptor cells, central neurons and nerve plexus. Both interneural and neuromuscular synapses are found in the nerve plexus. The apical organ is a collection of about 100 long, columnar cells each bearing a long cilium and a collar of about 10 microvilli. The cilia of the apical organ are twisted together to form an apical tuft. The ciliary rootlets of the apical organ cells are extremely long, reaching to the basal processes of the cells adjacent to the mesoglea. All three types of sensory cells are tall and slender in profile and are identified by the presence of one or more of the following features: microtubules, small vesicles, membrane-bound granules and synapses. The interneurons are bipolar cells with somas restricted to the aboral end, adjacent to the apical organ. All synapses observed are polarized or asymmetrical. A diagram including all the elements of the nervous system is presented and the possible functions of the nervous system are discussed in relation to larval behavior.     

Ultrastructure and receptor cell responses of the antennal grooved peg sensilla of Triatoma infestans (Hemiptera: Reduviidae)

Ultrastructural examination of grooved-peg (GP) sensilla on the antenna of fifth instar Triatoma infestans nymphs by scanning electron microscopy and transmission electron microscopy reveal that they are 8–18 μm long with a diameter of about 2–2.8 μm at the non-articulated base. Some pegs have a terminal pore. These double-walled wall-pore (dw-wp) sensilla have an outer cuticular wall with 13–18 longitudinal grooves at the distal part of the peg. Groove channels are present at the bottom of the grooves from which radial spoke channels lead into the inner sensillum-lymph cavity. A dendrite sheath connects the tip of the thecogen cell to the inner cuticular wall thus forming separated outer and inner sensillum-lymph cavities. Four or five bipolar receptor cells are ensheathed successively within the GP sensilla by the thecogen cell, trichogen and tormogen cells. The inner dendritic segments of each sensory cell give rise at the ciliary constriction to an unbranched outer dendritic segment which can reach the tip of the sensillum.Electrophysiological recordings from the GP sensilla indicate that they house NH₃, short-chain carboxylic acid and short-chain aliphatic amine receptor cells and can be divided into three functional sub-types (GP 1–3). All GP sensilla carry a receptor cell excited by aliphatic amines, such as isobutylamine, a compound associated with vertebrate odour. GP type 1 and 2 sensilla house, in addition, an NH₃-excited cell whereas the type 2 sensilla also contains a short-chain carboxylic acid receptor. No cell particularly sensitive to either NH₃ or carboxylic acids was found in the grooved-peg type 3 sensilla. GP types 1, 2 and 3 represent ca. 36, 10 and 43% of the GP sensilla, respectively, whereas the remaining 11% contain receptor cells that manifest normal spontaneous activity but do not respond to any of the afore mentioned stimuli.     

玉龙蝠蛾触角感觉器的扫描电镜观察

本文报道玉龙蝠蛾 Hepialus yulongensis Liang 触角感觉器种类、形态和分布的扫描电镜观察结果。蝠蛾触角呈丝状,由柄节、梗节和21—27个鞭节组成,总长2.3—2.7毫米,柄节比以后各节长,触角表面缺少隆起的网纹。触角感觉器计有七种,其名称为毛形感器、刺形感器、腔锥感器、锥形感器、鳞形感器、Bohm氏鬃毛及仅出现于雄蛾的钟形感器。根据中心栓的长度,腔下陷的深度和直径,腔锥感器基本上可分为长栓和短栓两种形态类型,腔的周围都无向内倾斜的缘栓;毛形感器可进一步分为A型和B型;Bohm氏鬃毛数量多,主要分布于柄节、梗节,但在端节也能见到。     

Poreless sensilla with inflexible sockets

Poreless sensilla (np-sensilla) on the antennae of 18 species from 9 insect orders, and on the maxillary palps of Periplaneta americana were investigated using chemo- and cryofixation. The number of np-sensilla is low. Common features of these sensilla are: (a) the presence of a peg, (b) the lack of pores that lead to the dendritic outer segments (DOS), (c) the lack of socket structures, which would indicate flexibility, and (d) the presence of three types of sensory cells. The type-1 sensory cells are characterized by large DOS, which proceed into the peg where they fit tightly to its wall. As a rule, two DOS are present, being arranged in bilateral symmetry. Within them, in two species, a pattern of microtubules similar to that of a tubular body was observed. In the type-2 sensory cells, the DOS end beneath the peg and mostly display membrane invaginations. In the type-3 sensory cell, the DOS is an unmodified 9 X 2 + 0 cilium. Electrophysiological investigation of the np-sensillum in the maxillary palp of Periplaneta showed the presence of a hygro- and/or thermoreceptor. In a comparison of np-sensilla with an inflexible socket in different insect species, it is shown that these sensilla represent one fundamental sensillum type and that their structural features can be regarded as adaptations to hygro- and thermoreception.     

Digitiform Sensilla on the Maxillar Palp of Coleoptera

The fine structure of the digitiform sensilla on the distal segment of the maxillar palps of Tenebrio and Dermestes is described. Each sensillum is associated with a single sensory cell and three enveloping cells, which enclose two receptor lymph cavities. The inner receptor lymph cavity of both species shows a different structural feature. Branches of the outer dendritic segments, which contain numerous microtubules, run to the tip of the hairshaft. A dendritic sheath extends to the apex of the peg. The hairshaft possesses a second canal, which is free of dendrites. The poreless hairshaft is inserted in a cuticular canal; the longer distal part of the shaft is positioned in a narrow superficial groove. The digitiform sensilla do not show the typical structures of mechanosensitive sensilla. The absence of pores in the setal wall does not point to a function as olfactory or gustatory hairs. The presumed function of the sensilla is discussed in relation to thermo-, hygro- and CO₂-receptors.     

Embryonic development and molting of the antennal coeloconic no pore- and double-walled wall pore sensilla in Locusta migratoria (Insecta,Orthopteroidea)

Summary The embryonic development of antennal coeloconic sensilla was studied at four stages between 132 and 252 h after oviposition in Locusta migratoria. Initially the anlagen of the sensilla consist of 2–4 sensory cells and 3 enveloping cells. Two additional cells contribute later to the formation of socket and pit. The dendritic outer segments of the sensory cells elongate before the trichogen process grows out (ecdysis type I) with exception of one sensory cell in anlagen of poreless (np) sensilla. Other differences between np and double-walled wall pore (dw wp) sensilla are not visible until at least about 220 h after oviposition. Molting, which was studied in four stages, follows ecdysis type I in both sensillum types. The fourth enveloping cell maintains its tight connection to the socket of the sensillum even after apolysis. Its apical portion is torn off and shed together with the old cuticle. The electron-dense material between the dendritic sheath and the cuticular wall of the peg in np sensilla, which is regarded important for stimulus transmission, is not deposited during retraction of the trichogen cell. The concentric walls and spoke channels characteristic of dw wp sensilla result from deposition of cuticular material around wedge-shaped projections of the trichogen cell. The typical trilaminar 15 nm cuticulin layer is produced only on the ridges of these sensilla. The first cuticular lining of the spoke channels is only 7 nm thick and of a different structure. A flocculent material surrounds the outgrowing trichogen process. It is continuous with the filling of the spoke channels and can thus be considered as component of the stimulus-transmitting material in the functioning intermolt dw wp sensilla.     

Fine structure of the galeal styloconic sensilla of larval Lymantria dispar (Lepidoptera: Lymantriidae)

Lepidopteran larvae possess two pairs of styloconic sensilla located on the maxillary galea. These sensilla, namely the lateral and medial styloconic sensilla, are each comprised of a smaller cone, which is inserted into a style. They are thought to play an important role in host-plant selection and are the main organs involved in feeding. Ultrastructural examination of these sensilla of fifth instar Lymantria dispar (L.) larvae reveal that they are each approximately 70 um in length and 30 um in width. Each sensillum consists of a single sensory peg inserted into the socket of a large style. Each peg bears a slightly subapical terminal pore averaging 317 nm in lateral and 179 nm in medial sensilla. Each sensillum houses five bipolar neurons. The proximal dendritic segment of each neuron gives rise to an unbranched distal dendritic segment. Four of these dendrites terminate near the tip of the sensillum below the pore and bear ultrastructural features consistent with contact chemosensilla. The fifth distal dendrite terminates near the base of the peg and bears ultrastructural features consistent with mechanosensilla. Thus, these sensilla each bear a bimodal chemo-mechanosensory function. The distal dendrites lie within the dendritic channel and are enclosed by a dendritic sheath. The intermediate and outer sheath cells enclose a large sensillar sinus, whereas the smaller ciliary sinus is enclosed by the inner cell. The neurons are ensheathed successively by the inner, intermediate, and outer sheath cells.     

Lamellated outer dendritic segments of a sensory cell within a poreless thermo- and hygroreceptive sensillum of the insect Carausius morosus

Summary A sensillum in a narrow pit with a broad cuticular collar, located in a sensillum field on the 12th segment of the antennae of Carausius morosus, was investigated electrophysiologically. After marking, it was also examined with the transmission and the scanning electron microscopes. The number of sensory cells within the sensillum varies between three and four. One cell, present in half of the sensilla studied, exhibits a simple cilium of the 9×2+0 type as outer dendritic segment. The outer segment of a second unit is noteworthy in that it divides near its ciliary base into two branches. These flatten to form lamellae, then fold and wrap around each other. The remaining two sensory cells bear unbranched or bifurcate outer segments which contain densely packed microtubules. Only these outer segments extend into the cuticular peg; the others end beneath its base. The cuticular peg is devoid of pore systems. Electrophysiological recording yielded evidence that a cold, a dry and a moist air receptor are present. The fourth unit did not respond clearly to stimulation.Supported by the Deutsche Forschungsgemeinschaft (Al 56/6)Research Fellow of the Alexander von Humboldt Foundation     

THE FINE STRUCTURE OF COCKROACH CAMPANIFORM SENSILLA

Campaniform sensilla on cockroach legs provide a good model system for the study of mechanoreceptive sensory transduction. This paper describes the structure of campaniform sensilla on the cockroach tibia as revealed by light- and electron-microscopy. Campaniform sensilla are proprioceptive mechanoreceptors associated with the exoskeleton. The function of each sensillum centers around a single primary sense cell, a large bipolar neuron whose 40 µ-wide cell body is available for electrophysiological investigation with intracellular microelectrodes. Its axon travels to the central nervous system; its dendrite gives rise to a modified cilium which is associated with the cuticle. The tip of the 20 µ-long dendrite contains a basal body, from which arises a 9 + 0 connecting cilium. This cilium passes through a canal in the cuticle, and expands in diameter to become the sensory process, a membrane-limited bundle of 350–1000 parallel microtubules. The tip of the sensory process is firmly attached to a thin cap of exocuticle; mechanical depression of this cap, which probably occurs during walking movements, effectively stimulates the sensillum. The hypothesis is presented that the microtubules of the sensory process play an important role in mechanoelectric transduction in cockroach campaniform sensilla.     

Gustatory organs of Drosophila melanogaster: fine structure and expression of the putative odorant-binding protein PBPRP2

In Drosophila, as in most insects, gustation is mediated by sensory hairs located on the external and internal parts of the proboscis and on the legs and wings. We describe in detail the organization and ultrastructure of the gustatory sensilla on the labellum and legs and the distribution of PBPRP2, a putative odorant-binding protein, in the gustatory organs of Drosophila. The labellum carries two kinds of sensilla: taste bristles and taste pegs. The former have the typical morphology of gustatory sensilla and can be further subdivided into three morphological subtypes, each with a stereotyped distribution and innervation. Taste pegs have a unique morphology and are innervated by two receptor cells: one mechanoreceptor and the other a putative chemoreceptor cell. PBPRP2 is abundantly expressed in all adult gustatory organs on labellum, legs, and wings and in the internal taste organs on the proboscis. In contrast to olfactory organs, where PBPRP2 is expressed in the epidermis, this protein is absent from the epidermis of labial palps and legs. In the taste bristles of the labellum and legs, PBPRP2 is localized in the crescent-shaped lumen of the sensilla, and not in the lumen where the dendrites of the gustatory neurons are found, making a function in stimulus transport unlikely in these sensilla. In contrast, PBPRP2 in peg sensilla is expressed in the inner sensillum-lymph cavity and is in contact with the dendrites. Thus, PBPRP2 could be involved as a carrier for hydrophobic ligands, e.g., bitter tastants, in these sensilla.     

The fine structure of thermo-/hygrosensitive sensilla in the silkmoth Bombyx mori: Receptor membrane substructure and sensory cell contacts

Summary The thermo-/hygroreceptive sensilla styloconica of the silkmoth Bombyx mori are located on the tips of the antennal branches. A small poreless cuticular peg is innervated by three sensory cells. The outer dendritic segments of two type-1 receptor cells, the presumed hygroreceptors, almost completely fill the peg lumen and are in close contact with each other. The outer dendritic segment of the third (type-2) receptor cell, the presumed thermoreceptor, forms lamellae below the peg base. The membranes of these lamellae are studded with knobs in orthogonal array, protruding into the extracellular space with the same orientation on facing lamellae. This Bossy Orthogonal Surface Substructure (BOSS) is assumed to play a role in thermoreceptor function. Contacts are observed between the outer dendritic segments, between the inner dendritic segments immediately below the ciliary segments, and between the sensory cell somata. These contacts, which are not found in the olfactory sensilla (s. trichodea and basiconica) of this species, indicate electrical interactions between the three sensory cells of the styloconic sensillum and possibly are involved in the antagonistic and/or bimodal response characteristics of thermo-/hygroreceptor cells.     

Functional morphology of a double-walled multiporous olfactory sensillum: the sensillum coeloconicum of Bombyx mori (Insecta, Lepidoptera)

The fine structure of coeloconic sensilla of Bombyx mori was studied in cryofixed specimens. These sensilla belong to the category of double-walled wall-pore sensilla. The pegs are approximately 10 mum long, located in pits on the dorsal side of the antennal branches, and longitudinally grooved in their distal half (grooved surface approximately 30 mum(2)). The central lumen contains the outer dendritic segments of usually five receptor cells, and is surrounded by up to 15 partially fused cuticular fingers. The peripheral lumina of these cuticular fingers are filled with material resembling wax-canal filaments. Radial spoke channels ( approximately 600 per peg), each 10-20 nm wide, connect the central lumen with the longitudinal groove channels. Groove and spoke channels are assumed to mediate the transport of odorant molecules from the outer epicuticular surface layers to the sensory dendrites. Thus the double-walled wall-pore sensilla represent a bauplan essentially different from single-walled wall-pore sensilla; the reason, however, why the two types are found together throughout the insect orders remains enigmatic. Other peculiar features of the coeloconic sensilla of the silkmoth are invaginations of the outer dendritic segments and direct contacts between the receptor cell somata. The latter may be the structural correlate to electrophysiological observations indicative of peripheral interaction between the receptor neurons. All three auxiliary cells have elaborately folded apical plasma membranes studded with portasomes and associated with an abundance of mitochondria; basally they often contact tracheal branches. As compared to the auxiliary cells of the single-walled olfactory sensilla of the same species, all the mentioned features are much more prominent and hint to a higher ion pumping activity at the border to the sensillum-lymph cavities.