Hair Tip Research Articles

Innervation of the cercal sensilla on the ovipositor of the Australian sheep blowfly (Lucilia cuprina)

ABSTRACT. The ovipositor of the female sheep blowfly, Lucilia cuprina (Wied.) (Diptera: Calliphoridae), has a complement of cercal sensilla that includes long, medium and short tactile hairs, two campaniform domes, four olfactory pegs, and ten double‐channelled gustatory hairs. This sensory array is suited to assess oviposition site resources, prior to and during the laying of an egg batch.The tactile hairs and campaniform sensilla are each innervated by a single, tubular body containing dendrite. The olfactory pegs are each innervated by a single, moderately branched dendrite, which gains access to the external environment via pores at the bottom of deep grooves in the peg wall. The gustatory hairs fall into two categories. Four hairs have a single, tubular body containing dendrite at their base, and four unbranched dendrites running up to the hair tip which has a terminal pore. Six of the taste hairs have no tubular body containing dendrite at the base, and three unbranched dendrites running up to a terminal pore.

Surface coats of pore tubules and olfactory sensory dendrites of a silkmoth revealed by cationic markers

Negatively charged surface coats have been demonstrated on the pore tubules and dendritic membranes of olfactory hairs of male Antheraea polyphemus silkmoths by application of the cationic markers lanthanum (La 3+), ruthenium red (RR), and cationized ferritin (CF). Lanthanum and RR diffused readily into the apically opened hairs, whereas CF penetrated only for a relatively short distance. Deposits of the markers are distributed as follows: the inner surfaces of the hair walls are stained by RR and to a small degree by CF: the surfaces of the pore tubules and the dendritic membranes are stained by all three markers. The pore tubules have the strongest affinity for CF. The number of pore tubule-membrane contacts seems to be increased by the cationic dyes. The dendrites are often penetrated by RR, which forms deposits on the inner membrane leaflets, the cytoplasmic microtubules, and microfilaments, and by La 3+, but never by CF. The observations provide support for the assumption that, first, the pore tubule-membrane contacts are formed via surface coats of both structures, possibly influenced by cations and, second, that the dendrites remain intact after pinching off the hair tips.

Formation of Calcium Oxalate Crystals Associated with Apothecia of the Discomycete Dasyscypha capitata

Calcium oxalate dihydrate crystals form at or near the tips of sterile hairs on the apothecia of the oak leaf litter discomycete Dasyscypha capitata. Early in their development, the crystals appear to be covered by a wall or membrane, whereas later they appear external. The crystals on each hair form a mass of crystals called a druse. Quite often the smaller crystals near the apex of the tip form a rosette, whereas the more peripheral crystals are much larger and display shapes possibly related to environmental factors. The formation and development of Dasyscypha crystals are compared with recent studies of other litter and soil fungi and their presence in other biological systems is put into perspective.

Coated and smooth vesicles in the biogenesis of cell walls, plasma membranes, infection threads and peribacteroid membranes in root hairs and nodules of white clover.

ABSTRACT Involvement of coated and smooth vesicles in the infection by rhizobia of root hairs and nodule cells of white clover was examined using electron microscopy of thin sections. Coated vesicles, about 100 nm in diameter including coat, were observed free in the plant cell cytoplasm and associated with root hair plasma membranes, infection thread membranes and peribac-teroid membranes. The number of coated vesicles seen associated with segments of the plasma membrane at the tip of the root hair was about 20-fold greater than the number associated with the plasma membrane towards the base of the root hair. Similarly, the number seen associated with segments of the infection thread membrane near the tip of the thread was about 20-fold greater than the number associated with the membrane towards the base of the thread. The number seen associated with segments of the peribacteroid membranes in recently infected nodule cells was comparable to the number associated with the plasma membrane towards the base of the root hair or with the infection thread membrane towards the base of the thread. Coated vesicles were observed in the vicinity of and associated with both proximal and distal faces of the Golgi bodies; they often possessed, while still attached to the Golgi cistemae, shorter coats than those observed on coated vesicles free in the cytoplasm. Coated vesicles contained electron-dense material that did not stain positively with Thiéry stain for polysaccharides, and which appeared to have been released into the region of the cell wall or peribacteroid space as a result of fusion of the vesicles with plasma membranes or peribacteroid membranes. Smooth vesicles were also observed in the vicinity of and associated with Golgi bodies, and in association with root hair plasma membranes, infection thread membranes and peribacteroid membranes. The smooth vesicles commonly contained material of varying electron density, which sometimes occurred in the form of droplets. Similar droplets seen in the region of the cell wall and in the peribacteroid space appeared to have resulted from the fusion of smooth vesicles with these membranes. It is proposed that both smooth and coated vesicles derived from Golgi bodies are involved in the biogenesis of cell walls, plasma membranes, infection threads and peribacteroid membranes in root hairs and nodules of white clover.

Lectin involvement in root‐hair tip adhesion as related to the Rhizobium‐clover symbiosis

Contact of adjacent root hairs of seedlings of white clover (Trifolium repens L. cv. Ladino and Louisiana Nolin) led to cell‐cell adhesion of root hair tips. The involvement of the root lectin, trifoliin A, in this phenomen was examined in slide cultures of axenically grown seedlings. Trifoliin A was detected by indirect immunofluorescence on root hair tips, which had adhered to one another. Seedlings grown under conditions which specifically reduce the levels of this lectin on the root surface (e.g., in the presence of 15 mM NO3– or 5 mM 2‐deoxy‐d‐glucose) had significantly fewer adhesions of root hair tips. In addition, flushing the slide cultures with 20 mM 2‐deoxy‐d‐glucose resulted in an immediate 4‐fold reduction in frequency of tip adhesions. These results are consistent with the lectin cross‐bridging model, which predicts that cell‐cell adhesions would occur when trifoliin A on root hair tips contacts complementary glycosylated receptors on neighboring root hairs.

Growth and coloration of Tradescantia stamen hairs cultured in vitro

Young stamens of Tradescantia clone 02 were cultured in vitro on agar media containing various combinations of three plant hormones, IAA, GA 3 and kinetin. Maximum growth of stamen hairs was observed with medium containing 5.0 mg/l IAA, 1.0 mg/l GA 3 and 0.1 mg/l kinetin. As much as a 10 cell increase was observed in stamen hairs on this medium, but the growth did not equal the normal in vivo growth. The hormonal concentrations of the medium which induced maximum coloration were 0.1 mg/l IAA, 1.0 mg/l GA 3 and 0.1 mg/l kinetin. Higher concentrations of sucrose also seemed effective in promoting coloration. The distribution pattern of colored cells along hairs (more coloration at hair tips) supports the idea that completion of cell division is one of the ‘triggers’ of coloration. The present study suggests the possibility of developing in vitro culture techniques of Tradescantia stamens.

Study of theRhizobium japonicum-soybean symbiosis

Capsular polysaccharides were isolated fromRhizobium japonicum (61A76NS) and conjugated to a fluorescent dye to determine if the specificity in theRhizobium japonicum-soybean symbiosis is expressed by a component (lectin) located on soybean roots which binds to the sugars of the bacterial capsules. The conjugated Fraction A capsular polysaccharides ofR. japonicum bound only to the root hair tips of soybean seedlings. The polysaccharide would not bind specifically to the roots of clover or alfalfa seedlings. Rhodamine conjugated polysaccharides ofR. japonicum could be inhibited from binding to soybean root hairs by the addition of N-acetylgalactosamine or galactose, effective hapten inhibitors of this type of binding. This is the first report of hapten-reversible binding of an isolated rhizobial component to soybean root hairs, the differentiated epidermal cells which are subsequently infected by this nitrogen-fixing symbiont.

The Imprints of the Human Tectorial Membrane

The human tectorial membrane was observed with the scanning electron microscope. Imprints were observed on the undersurface of the middle zone of the tectorial membrane in a configuration corresponding to the arrangement of hairs on the outer sensory cells, indicating the insertion of the sensory hair tips. the imprints were arranged not only in a single line forming a W shape (single imprint), but also in 2 or 3 lines (multiple imprint) in the human. Oblique SEM observation of the imprints showed that there was a slight elevation of the basal layer of the tectorial membrane bearing the imprints (W-shaped elevated zone). Furthermore, a deep hollow surrounded the imprints. the findings are discussed from a functional viewpoint.

Scanning Electron Microscopy of Rhizobium trifolii Infection Sites on Root Hairs of White Clover

White clover root hairs which were inoculated with Rhizobium trifolii 4S (infectious strain) contained infection threads which were observed by light microscopy and scanning electron microscopy. Three morphological types of root hairs retaining infection threads were recognized. The bacteria were strongly attached between the surfaces of two plant cell walls as follows: between surfaces of a root hair tip curled back on itself, between a protuberance from a root hair and its cell surface, or between two root hair tips clinging together. An anatomical analysis documented the attachment site of the infection thread sheath from the inside of the root hair cell.

The differential effects of cytochalasin B on microfilament populations and cytoplasmic streaming

Two distinguishable populations of microfilaments (mfs) can be identified in the radish root hair. Bundles of mfs are found throughout the cytoplasm, excluding the tip region of the hair. Single mfs occur only as a cortical array, specifically associated with the microtubules. Both mf populations are oriented parallel to the direction of streaming. Hairs grown in 5 μg/ml cytochalasin B (CB) exhibit site-specific differential responses to the drug in both their streaming pattern and sensitivity of their mfs. Cytochalasin B elicits the following responses: 1. cytoplasmic streaming is reduced in all regions of the hair; 2. small particles ( 1 μm in diameter) no longer stream but exhibit an oscillatory or rotational motion; 3. filament bundles show increasing sensitivity to CB along the length of the hair; 4. single mfs show decreasing sensitivity to CB along the hair length. The effects of CB on cytoplasmic streaming can be related to its effects on both mf populations, thus suggesting that although mf bundles are probably involved in streaming in the sub apical and basal regions of the hair, single mfs are most likely involved in generating the slower, more irregular streaming patterns exhibited in the hair tip and CB-treated hair base.

The ultrastructure of the otolithic membrane and otolith in the juvenile mummichog, Fundulus heteroclitus.

The sagitta otolithic membrane of Fundulus heteroclitus consists of two different zones. A structured zone (gelatinous layer), which usually exhibits a reticulated or honeycomb-like architecture, is composed of tightly arranged fibrous material and covers only the sensory region of the macula. The gelatinous layer extends from the otolith surface to the tips of the sensory hairs, and probably functions primarily as a mechanoreceptor. The arrangement of this zone is closely associated with specific overlying structural features of the otolith surface and may also influence the pattern of mineral deposition to some degree. A nonstructured zone (subcupular meshwork) consists of fibers in very loose networks and covers both sensory and nonsensory regions of the macula. Over the sensory region, some of this fibrous material extends from the epithelial surface, through pores in the gelatinous layer, to the surface of the overlying otolith. In the nonsensory region, fibers of the subcupular meshwork are relatively more numerous and extend around the peripheral margin of the otolith. Evidence is presented which suggests that the fibrous material of the subcupular meshwork is incorporated into the otolith as an organic matrix constituent. New aspects on the ultrastructure of the otolith are presented and discussed.

Copper in green hair: a quantitative investigation by electron probe x-ray microanalysis.

Eleven cases of green hair were collected and hair tips were analyzed in the electron microscope by energy-dispersive x-ray microanalysis. In all cases, remarkable copper concentrations could be demonstrated (0.2-1.8% w/w). In normal hair the concentration of copper was below the detection limit (0.02% w/w). Analyses of hair cross sections showed a concentration gradient from the periphery toward the center, the periphery having higher values. This observation is in agreement with suspected contamination of the hair with copper from extraneous sources: analysis of the tapwater in patients' homes showed elevated copper concentrations. In addition, the water showed aggressive properties (pH outside the recommended range, high nitrate concentrations, heavily chlorinated). Investigations by transmission electron microscopy showed damage in the endocuticula. Experimental studies of normal unaffected hair fibers showed that treatment with a copper salt alone could result in binding of copper to the hair but that the extent of copper binding could be greatly increased by damaging the cuticula with chlorinated water. It is suggested that aggressive water attacks copper tubings leading to increased copper concentrations in tapwater and causes cuticular damage, which facilitates entry of copper into the hair.

Influence of the viscous substance at the tip of the labellar hairs ofPhormia regina M. on the effectiveness of stimulation by cations and anions

The stimulating effectiveness of salt solutions on the labellar taste hairs ofPhormia regina M. is discussed on the basis of ion diffusion properties across the mucopolysaccharidic layer at the hair tip.

Bacterial polysaccharide which binds Rhizobium trifolii to clover root hairs.

Immunofluorescence, quantitative immunoprecipitation, and inhibition of bacterial agglutination and passive hemagglutination indicate that cross-reactive antigenic determinants are present on the surface of Rhizobium trifolii and clover roots. These determinants are immunochemically unique to this Rhizobium-legume cross-inoculation group. The multivalent lectin trifoliin and antibody to the clover root antigenic determinants bind competitively to two acidic heteropolysaccharides isolated from capsular material of R. Trifolii 0403. The major polysaccharide is an antigen which lacks heptose, 2-keto-3-deoxyoctulosonic acid, and endotoxic lipid A. The minor polysaccharide in the capsular material of R. Trifolii 0403 contains the same antigen in addition to heptose, 2-keto-3-deoxyoctonate, and lipid A. The acidic polysaccharides of two strains of R. trifolii share the clover r-ot cross-reactive antigenic determinant despite other differences in their carbohydrate composition. Studies with monovalent antigen-binding fragments of anti-clover root antibody and Azotobacter vinelandii hybrid transformants carrying the unique antigenic determinant suggest that these polysaccharides bind R. trifolii to the clover root hair tips which contain trifoliin.

An ultrastructural study of the tips of four classical bimodal sensilla with one mechanosensitive and several chemosensitive receptor cells

1. The ultrastructure of the tips of four insect sensory hairs was examined in serial section. They are characterized as follows: a. an apical pore opening in the dendrite-containing canal (dC); b. a double lumen in the hair shaft; c. multiple and bimodal innervation. 2. Variation was found in the form and cross-sectional area of the apical pores. 3. The two lumina, one of which contains the dendrites, do not appear to communicate with one another; openings were not found. 4. A tubular body in one of the receptor cells, whose dendrite terminates at the base of the hair shaft, identified it as mechanosensitive. The dendrites of the other (2–5) receptor cells lack apparent modal-specific structures and terminate at somewhat varying levels below the apical pore. 5. The three-layered cuticle (endocuticle, interstitial layer, exocuticle) of the hair shaft is traversed by narrow perforations which, as demonstrated by tracer experiments, are penetrated by small silver particles. Although the interstitial layer is the thinnest layer at the base of the hair, it becomes the most prominent layer at the tip of the hair. 6. An intensely stained substance coats part or all of the tip of the hair. 7. The ultrastructure of the tips of these sensory hairs, two of which have been identified electrophysiologically as both mechanoreceptive and chemoreceptive, is discussed in relation to their function.

The typology and topography of the tarsal chemoreceptors of the blow flies Calliphora vicina Robineau-Desvoidy and Phormia terranovae Robineau-Desvoidy and the Housefly Musca domestica L.

A comparative morphological study concerning typology and topography of chemoreceptors on the prothoracic legs of Calliphora vicina, Phormia terranovae and Musca domestica has been carried out. The typological criteria of Grabowski and Dethier ('54) and Hansen and Heumann ('71) were used. A single criterion, the shape of the tip, was used to define the different types of chemoreceptors. A-hairs have a rhombic pore at the side of the tip; B-hairs have an oval pore at the tip apex and D-hairs have a rectangular pore under an undulated, cap-like structure at the hair tip. A-, B-and D-hairs were found in the tarsomeres of Phormia; in Musca and Calliphora only B- and D-hairs were found. An opening and closing mechanism may operate on the pores of the tips of the chemoreceptors. Chemoreceptors were counted and a topographical map was completed, using SEM-techniques. Topographical maps are of value in electrophysiological and behavioural research, where only a limited optical magnification is possible.

Mucilage on the Root Surface and Root Hairs of Sorghum: Heterogeneity in Structure, Manner of Production and Site of Accumulation

Small drops of a mucilaginous character near the tip of root hairs were seen by light microscopy in several species of Sorghum and the Sorghum hybrid Vidan. Electron microscopy revealed that the drops are formed from at least two distinct substances, both apparently secreted from the endoplasmic reticulum. In addition, a patchy, fibrillar mucilaginous layer, also with at least two components, was found on the cell wall of the root hairs and on the outer wall of ordinary root epidermal cells. Golgi bodies as well as mitochondria take part in its production. As a rule, the mucilaginous patches are colonized by bacteria

SCANNING ELECTRON MICROSCOPIC OBSERVATION ON THE COCHLEA TREATED WITH FROZEN RESIN CRACKING METHOD

By the use of frozen resin cracking method, scanning electron microscopy (SEM) makes it possible to investigate the deeper and finer structures of the inner ear. Another merit of this method is to obtain any sections of the organs without any significant artifactual damages to the tissues. The inner ears of the guinea pig were fixed and stained with osmic acid. After the cracking procedure frozen specimens were subjected to CO2 critical point drying, the conductive coating of carbon and gold successively, and finally submitted to SEM observation. Some of the remarkable findings are as follows: 1) The cellular pattern of stria vascularis, spiral prominence and outer sulcus was different each other in the lateral wall of the cochlear duct. 2) A considerably big space was found around nerve fibers within the osseous spiral lam-ina. Small holes of about 3ls in diameter were also noted on the lower surface of the osseous spiral lamina. These holes and the space might be intercommunicated between cortilymph and perilymph in the scala tympani. 3) The tectorial membrane seemed to be composed of two layers, namely, the upper fibrous and the lower basal or granular layer. Regarding the relation of the tectorial membrane to hairs of the hair cells, situations were fairly different between outer and inner hair cells. Tips of hairs in the outermost row of outer hair cells penetrated into the granular layer of the membrane making a firm contact. On the other hand, at the lateral side of the outermost row, hairs of the inner hair cells were attached to the tectorial membrane with granular substances protruding from the undersurface of the granular layer. 4) At the hook region, hair cells became less in number mainly at the outermost row closer to the cecum vestibuli.

Simultaneous chemical and electrical stimulation of labellar taste hairs of the blowfly Calliphora vicina

When recording from the tip of insect taste hairs, responses to chemical stimulation may be influenced by electrical currents, such as the preamplifier's input bias current. The effect of electrical currents on firing frequency of the salt receptor cell to KCl and NaCl stimulation was determined in labellar ‘aboral’ and ‘adoral’ taste hairs of the blowfly Calliphora vicina. Negative currents always decreased spike frequency, whereas positive currents either increased it, or did not change it significantly. Spike frequency changed less than 1% per 5 × 10 −11 A. A consistent picture of the electrophysiology of blowfly taste hairs is given. It includes a distal pore, present in the dendrite-free lumen of the hair. It abandons the concept of a generator current that transmits excitation from the distal, chemoreceptive part of the taste cell dendrite to the action potential generator in or near the taste cell body. The experimental results are interpreted on the basis of this picture. It is concluded that the ‘electrophoretic effect’ of the electrical current is very small. Thus, the measured effect should mainly be due to a ‘direct effect’ of electrical current on electrically excitable structures in the salt receptor cell, particularly in its dendrite.

Hair regeneration during moulting in the spiderCiniflo similis (Araneae, Dictynidae)

The mechanoreceptive and chemoreceptive hairs on the legs of the cribellate spiderCiniflo similis were examined during the moulting cycle. In mechanoreceptive hairs the new hair shaft is formed around the extended dentrites, which emerge from near the tip of the newly forming hair and continue to the old sensillum within the extended dendritic sheath. Thus there is no ecdysial canal in the base of the hair shaft as found in insect mechanoreceptive hairs. The dendritic connection with the old hair is maintained until shortly before ecdysis by which time new tubular bodies have developed in the same dendrites at the base of the new hair. In chemoreceptive sensilla the new hair shaft is also formed around the elongated outer segment of the dendrites (19 chemosensitive and 2 mechanosensitive). The two mechanosensitive dendrites develop new tubular bodies at the base of the hair. As ecdysis occurs the old dendritic sheath and dendrites are snapped off at the tip of the new hair but the pore remains open. The ultrastructural evidence indicates that the roles of the three main enveloping cells are as follows: The dendritic sheath cell secretes the dendritic sheath, the middle enveloping cell forms the hair shaft while the outer enveloping cell forms the socket. This pattern corresponds closely to that observed in insecta sensilla. The extreme length of the chemoreceptive dendrites during moulting is mentioned in connection with receptor function. The unique multi-layered nature of the middle enveloping cell is seen as a device for the formation of regularly occurring rows of small spines on the shaft of the hair.