Tormogen Cell

2008 ◽  
pp. 3832-3832
Author(s):  
James E. O’Hara ◽  
Igor UsUpensky ◽  
N. J. Bostanian ◽  
John L. Capinera ◽  
Reg Chapman ◽  
...  
Keyword(s):  
Tormogen Cell

The Function and Fine Structure of the Cephalic Airflow Receptor in Schistocerca Gregaria

1966 ◽  
Vol 1 (4) ◽  
pp. 463-470
Author(s):  
D. M. GUTHRIE
Keyword(s):  
Fine Structure ◽  
Cell Body ◽  
Schistocerca Gregaria ◽  
Tube Wall ◽  
Sense Organ ◽  
Hair Shaft ◽  
Sensory Axons ◽  
Steady Rate ◽  
Neuron Cell Body ◽  
Tormogen Cell

Electron micrographs of parts of the sense organ showed that the dendritic axis consisted of a large and a small envelope containing microtubules as their main inclusion. The envelopes are supported by a thick-walled tube believed to be part of the Ist-tier sheath cells. The small envelope is segregated from the large envelope near its apex by a fold of the tube wall. The packing of the neurotubular array within the small envelope is both more dense and more regular than within the large envelope. The tube is separated by an extracellular space from the trichogen-tormogen cell. Sections through the apex of the dendrite reveal a homogeneous cap unlikely to be part of a structure continued into the upper region of the hair shaft. No ciliary structures were visible within the dendrite, whose microtubules pass into the neuron cell body proximally. Sections through the neuron cell body reveal branched mitochondria, and numerous microtubules. Rates of discharge in sensory axons from these hair organs produced by deflexion of the hair shaft were found to be within the range 300-100 impulses/sec. There is an initial phase of rapid adaptation which gives place to a steady rate. It is suggested that the fine structure of the receptor may indicate mechano-electrical transduction at a more proximal level than is believed to be the case in some other types of receptor. The diaphragms that support the hair shaft laterally can be seen to be composed of fine cuticular strands.

Cellular organization and fine structure of type II microtrich sensilla in gammaridean amphipods (Crustacea)

1999 ◽  
Vol 77 (1) ◽  
pp. 88-107 ◽  
Author(s):  
V J Steele ◽  
D H Steele
Keyword(s):  
Sensory Neurons ◽  
Sensory Cell ◽  
Cell Process ◽  
Outer Cell ◽  
Type Ii ◽  
Cellular Organization ◽  
Insect Sensilla ◽  
Transmission Electron ◽  
Cell Processes ◽  
Tormogen Cell

The cellular organization of type II microtrich sensilla was studied in male Anonyx lilljeborgi Boeck, 1871 (Lysianassoidea) by light and transmission electron microscopy. The sensillum consists of two bipolar sensory neurons and three concentric sheath cells. The sensory cell bodies are subepidermal. In each sensillum both dendrites are enclosed by the thecogen cell process. The inner dendritic segments are filled with mitochondria and lucent vesicles and expand in the epidermis into a spindle-shaped swelling. One of the neurons gives rise to two cilia and the second to a single cilium. These three outer dendritic segments lie in the receptorlymph cavity. The dendritic sheath, secreted by the thecogen cell process, completely ensheaths the outer dendritic segments. The trichogen (middle) cell and the tormogen (outer) cell incompletely enclose the thecogen cell, but their processes form autojunctions around the dendritic sheath in the apical epidermis. In premolt, the trichogen cell processes project into the exuvial space. The cytoplasm of the tormogen cell and the bordering epidermal cells contains coarse osmiophilic inclusions. All the cells of the sensillum are joined by desmosomes. The sensilla structurally resemble chemosensory (gustatory) insect sensilla.

Morphology of the elongate sensillum placodeum on the antennae of Aphidius smithi (Hymenoptera: Aphidiidae)

1978 ◽  
Vol 56 (4) ◽  
pp. 519-525 ◽  
Author(s):  
J. H. Borden ◽  
A. Rose ◽  
R. J. Chorney
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Host Finding ◽  
Dendritic Branch ◽  
Tormogen Cell ◽  
Dendritic Branches ◽  
Relationship Of ◽  
The Relationship ◽  
Cuticular Surface ◽  
Scanning Electron

Elongate placoid sensilla were present on all 20 flagellar segments in five male Aphidius smithi and all but the basal 1 of 17 segments in five females. They are oriented longitudinally, approximately equidistant around the circumference of a segment. Scanning electron microscopy of the internal cuticular surface disclosed lamellae which divide the sensillum into lateral and median channels. Many transverse ridges are present in the ceiling of the median channel. Unlike other species, there is no cuticular floor of the sensillum. Numerous nerve cell bodies in the subcuticular tissue give rise to dendritic processes, a ciliary region, and a region of dendritic branches which lie parallel to each other within the 1-μm-wide median channel underneath the 0.1- to 0.25-μm-thick dome. Each dendritic branch is composed of a neurotubule surrounded by a plasma membrane. The ascending dendrites are flanked by the microvilli of the trichogen cell. A tormogen cell encloses the trichogen cell and extends into the lateral channels of the sensillum. The relationship of minute pores in the dome with the underlying dendritic branches is unclear. The hypothesis is advanced that the sensilla may be involved in host finding through perception of infrared radiation.

In vitro analyses of cuticular differentiation at the chromosomal level in Lucilia sericata

Genome ◽  
1988 ◽  
Vol 30 (4) ◽  
pp. 603-607 ◽  
Author(s):  
Manfred G. Schmiemann ◽  
Michael M. Bentley1
Keyword(s):  
Culture Medium ◽  
Polytene Chromosomes ◽  
Culture Conditions ◽  
Lucilia Sericata ◽  
In Vitro Cultivation ◽  
Pupal Development ◽  
Chromosome Conformation ◽  
Tormogen Cell

The large bristles of flies sclerotize and melanize during the pupal phase well before the rest of the cuticle. Each bristle is the product of two cells, the trichogen cell and the tormogen cell. Both their nuclei exhibit analyzable polytene chromosomes. The pupal metathoracic integument of Lucilia sericata has been excised and cultivated in Schneider's Drosophila medium for extended periods of time. Among the differentiations taking place in vitro, the most obvious is the stiffening and coloring of the bristles. The in vitro differentiation very much resembles the in vivo differentiation in its timing and appearance. Explants excised early in pupal development cannot differentiate in vitro, while those excised and cultured at later stages can. Actinomycin D was administered to the culture medium and the incorporation of [3H]uridine was analyzed after long incubations to determine if this process was a reaction of dead cuticle or controlled by living cells. The analysis of chromosome structure and puffing patterns in the five polytene chromosomes of the trichogen cell after in vitro cultivation shows that transcriptional activity is not dependent on the existence of normal chromosome conformation. The degree of pycnotic reaction and puff induction of the nuclei, however, varied under different culture conditions. The capacity of this system for differentiation can be used to study in vitro chromosomal activity during the course of development.Key words: in vitro, polytene chromosomes, sclerotization, cuticle.

Memoirs: The Structure and Development of Wax Glands of Pseudococcus Maritimus (Homoptera, Coccidae)

1937 ◽  
Vol s2-80 (317) ◽  
pp. 127-148
Author(s):  
PRISCILLA FREW POLLISTER
Keyword(s):  
Central Cell ◽  
Cell Multiplication ◽  
Histological Structure ◽  
Large Reservoir ◽  
The Third ◽  
Neck Cell ◽  
General Plan ◽  
Tormogen Cell ◽  
Peripheral Cells ◽  
Pseudococcus Maritimus

The females of Pseudococcus maritimus have three types of multicellular wax-glands, one with a triangular external pore, another opening through a long tube, and a third with a multilocular aperture. The first two are widely distributed on all surfaces of the adult. The third is restricted to the ventral surfaces of the last five segments. This multiloeular type is found only in the adult. The triangular glands are found at all stages and these structures progressively increase in number with each successive instar. The tubular type appears first in the second instar; the number is reduced in the third instar; and in the adult it is again increased to the largest number found at any stage. The three glands are all modifications of one general plan of histological structure. The glandular elements are sub-epidermal cells arranged in a ring of peripheral cells surrounding a single central cell. There are three peripheral cells in the triangular gland and ten in each of the others. The peripheral cells are uninucleate and contain vacuoles of secretory material. The central cell of the tubular and triangular glands has a large and two small nuclei and contains a large reservoir, from which a chitinized duct system leads to the gland-pore. The central cell of the multilocular gland is small and relatively undifferentiated. The author favours the view of Šulc that the wax is probably secreted by the peripheral cells, while the central cell secretes a substance that causes the wax filaments to adhere to form large cylinders. The glands are developed by cell-multiplication from the epidermis at the time when it is freed from the cuticula at the beginning of ecdysis. After the initial period of cell-multiplication the first differentiation is the development of the external pore within the neck-cell. Later in the development of multilocular glands it is believed the glandular cells grow through the neck-cell to establish the functional relationship with the pore. It is suggested that this is analogous to the relationship between tormogen cell and trichogen cell in the development of a spine.

Observations on the Nervous System of the Flight Apparatus in the Locust Schistocerca Gregaria

1964 ◽  
Vol s3-105 (70) ◽  
pp. 183-201
Author(s):  
D. M. GUTHRIE
Keyword(s):  
Nervous System ◽  
Schistocerca Gregaria ◽  
Sensory System ◽  
Outer Region ◽  
Hair Shaft ◽  
Distal Process ◽  
Motor Neurones ◽  
The Central Nervous System ◽  
Tormogen Cell ◽  
Hair Shafts

The hair sense-organs of the head are part of a sensory system affecting the activity of motor neurones to the flight muscles. They possess curved hollow hair shafts inserted in a complex socket. A large neurone is present beneath the socket and is partly surrounded by a large formative cell, the trichogen-tormogen cell. The distal process passes up into the expanded base of the hair shaft. Fine connexions between the outer region of the formative cell and the inner part round the neurone process, possibly limiting angular sensitivity, can be seen in some specimens, although the form and fine structure of the hair shaft is almost certainly important in this respect. The axons from the 5 areas of hair organs are collected together into a dorsal tegumentary nerve, those from area three forming a short subocellar nerve. Electronmicrographs of this nerve show that there are a number of large fibres (1 to 5 µ), and many more smaller fibres (1.0 to 0.1µ.) with no sheaths. There were estimated to be 5,500 fibres in each dorsal tegumentary nerve. Within the central nervous system, the dorsal tegumentary fibres may follow one of 4 routes, as follows. They may (i) pass forward into the protocerebrum, (ii) end in zones of terminals in the deutocerebral region, (iii) a few thick fibres pass down into the suboesophageal ganglion and then cross over to the opposite side giving off collaterals before descending to the pterothoracic ganglia, (iv) most of the fine descending fibres probably end at the suboesophageal level, a proportion of them crossing over here. The motor neurones to the longitudinal indirect muscles M81 and M82 consist of 4 anterior and 1 posterior cell respectively, and possess large and striking cell bodies, whose collaterals could be seen in the dorsal zones of motor terminals. The probable internuncial links between the sensory and motor arcs are outlined.

scholarly journals The development of the bristles in normal and some mutant types of Drosophila melanogaster

1942 ◽  
Vol 131 (862) ◽  
pp. 87-110 ◽  
Keyword(s):  
Drosophila Melanogaster ◽  
Single Cell ◽  
Epidermal Cells ◽  
After Puparium Formation ◽  
Puparium Formation ◽  
Tormogen Cell

This paper describes the development of the normal macro- and micro-chaetae of Drosophila , together with that of twelve mutant types. The phenotypes of twenty combinations of these genes have been studied. Each normal bristle is secreted by a single cell, the trichogen, which lies beneath a tormogen cell which secretes a socket. These bristle cells are first distinguishable in the epidermis at about 15 hr. after puparium formation, when they have already divided to form a pair, and are slightly larger than the normal epidermal cells. The secretion of the bristle proceeds most rapidly between 30 and 55 hr., during which time the bristle cells are very large and obviously highly polyploid. The socket, apparently, does not completely enclose the base of the bristle in the earliest stages. The development of the microchaetae is essentially similar to that of the macrochaetae. The actions of the twelve genes can be summarized as follows: Scute causes a primary absence of certain bristle cells, and extra-bristle-complex -41 e and hairy the presence of supernumerary groups. Split frequently causes an extra division, so that a group of four cells is formed; these may be arranged as two trichogens and two tormogens, or one trichogen and three tormogens; or the whole group may fail to reach the surface of the epithelium, when no bristle or socket is formed. Dichaete may produce an effect similar to the last-described of split , and it may also cause an extra division of the trichogen, producing a double bristle in a single socket. Hairless causes the trichogens of some bristle groups to lie level with the tormogens, and to develop like them into sockets. In Stubble the tormogens are shifted rather to one side of the trichogens, so that the bristle is less closely invested by the socket, and becomes thicker and shorter. In shaven-naked the trichogen is irregularly displaced, becoming more or less converted into a tormogen; the small bristle which may be secreted is often peculiarly fanned out at the tip, suggesting an effect of the gene on the nature of the material secreted. Spineless and morula slow down the growth of the bristle cells. Singed, forked and Bristle all affect the nature of the bristle secretion, there being some reason to suggest that the effects of Bristle and singed may be similar and different to that of forked.

Development of adult sensilla on the wing and notum of Drosophila melanogaster

Development ◽  
1989 ◽  
Vol 107 (2) ◽  
pp. 389-405 ◽  
Author(s):  
V. Hartenstein ◽  
J.W. Posakony
Keyword(s):  
Cell Lineage ◽  
Precursor Cell ◽  
Random Pattern ◽  
Wing Margin ◽  
After Puparium Formation ◽  
First Order ◽  
Accessory Cells ◽  
Puparium Formation ◽  
Tormogen Cell ◽  
Adult Drosophila

We have investigated the temporal pattern of appearance, cell lineage, and cytodifferentiation of selected sensory organs (sensilla) of adult Drosophila. This analysis was facilitated by the discovery that the monoclonal antibody 22C10 labels not only the neuron of the developing sensillum organ, but the accessory cells as well. The precursors of the macrochaetes and the recurved (chemosensory) bristles of the wing margin divide around and shortly after puparium formation, while those of the microchaetes and the stout and slender (mechanosensory) bristles of the wing margin divide between 9 h and 18 h after puparium formation (apf). The onset of sensillum differentiation follows the terminal precursor division within a few hours. Four of the cells in an individual microchaete organ are clonally related: A single first-order precursor cell divides to produce two second-order precursors; one of these divides into the neuron and thecogen cell, the other into the trichogen cell and tormogen cell. Along the anterior wing margin, two rounds of division generate the cells of the mechanosensory sensilla; here, no strict clonal relationship seems to exist between the cells of an individual sensillum. At the time of sensillum precursor division, many other, non-sensillum-producing cells within the notum and wing proliferate as well. This mitotic activity follows a spatially non-random pattern.

Cis-interactions between Delta and Notch modulate neurogenic signalling in Drosophila

Development ◽  
1998 ◽  
Vol 125 (22) ◽  
pp. 4531-4540 ◽  
Author(s):  
T.L. Jacobsen ◽  
K. Brennan ◽  
A.M. Arias ◽  
M.A. Muskavitch
Keyword(s):  
Ectopic Expression ◽  
Notch Signalling ◽  
Dominant Negative ◽  
Notch Signalling Pathway ◽  
Dominant Negative Form ◽  
A Cell ◽  
Developmental Contexts ◽  
Tormogen Cell ◽  
To Receive ◽  
Negative Form

We find that ectopic expression of Delta or Serrate in neurons within developing bristle organs is capable of non-autonomously inducing the transformation of the pre-trichogen cell into a tormogen cell in a wide variety of developmental contexts. The frequencies at which Delta can induce these transformations are dependent on the level of ectopic Delta expression and the levels of endogenous Notch signalling pathway components. The pre-trichogen cell becomes more responsive to Delta- or Serrate-mediated transformation when the level of endogenous Delta is reduced and less responsive when the dosage of endogenous Delta is increased, supporting the hypothesis that Delta interferes autonomously with the ability of a cell to receive either signal. We also find that a dominant-negative form of Notch, ECN, is capable of autonomously interfering with the ability of a cell to generate the Delta signal. When the region of Notch that mediates trans-interactions between Delta and the Notch extracellular domain is removed from ECN, the ability of Delta to signal is restored. Our findings imply that cell-autonomous interactions between Delta and Notch can affect the ability of a cell to generate and to transduce a Delta-mediated signal. Finally, we present evidence that the Fringe protein can interfere with Delta- and Serrate-mediated signalling within developing bristle organs, in contrast to previous reports of the converse effects of Fringe on Delta signalling in the developing wing.

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