Extent and properties of the regeneration field in the larval legs of cockroaches (Leucophaea maderae)

Development ◽  
1974 ◽  
Vol 31 (3) ◽  
pp. 557-572
Author(s):  
Horst Bohn
Keyword(s):  
Anterior Part ◽  
Posterior Region ◽  
Anterior Region ◽  
Posterior Border ◽  
Anterior Border ◽  
Experimental Conditions ◽  
Leucophaea Maderae ◽  
Reversed Polarity ◽  
Anterior Posterior

Extirpation experiments have been performed on the larvae of cockroaches (Leucophaea maderae) to determine the extent and properties of the regeneration field of the legs of these insects. The distal segments, including the coxa, may all be removed without loss of regenerative capability; but regenerative capability eventually disappears if more proximal parts are removed. There are two regions adjoining the coxa anteriorly and posteriorly which are both important for leg regeneration. The anterior region consists of the sclerotized basal parts of the leg mainly formed by the trochantin and the praecoxa. The posterior region is an unsclerotized membranous area extending from the posterior border of the coxa to the anterior border of the next segment. This membrane is called ‘leg-inducing membrane’. If only one of these two regions is present, no leg regeneration will occur. The interaction of both parts is necessary to allow the formation of a complete leg. An extra leg with reversed anterior–posterior polarity is formed when the ‘leg-inducing membrane’ of one segment is brought into contact with the sclerites of the following segment after extirpation of the membranous area which normally separates them. This membranous area, which represents the most anterior part of a segment, is called ‘sclerite-inducing membrane’, for if the basal sclerites or part of them are combined with this membrane only sclerites are formed, either in normal or reversed polarity depending on the experimental conditions.

Extent and properties of the regeneration field in the larval legs of cockroaches (Leucophaea maderae)

Development ◽  
1974 ◽  
Vol 32 (1) ◽  
pp. 69-79
Author(s):  
Horst Bohn
Keyword(s):  
Abdominal Segment ◽  
Anterior Margin ◽  
Posterior Border ◽  
Anterior Border ◽  
Leucophaea Maderae ◽  
Anterior Half ◽  
Regenerative Ability ◽  
Transplantation Experiments ◽  
Anterior Posterior

The investigation of the regeneration field of the larval legs of cockroaches (Leucophaea maderae), which commenced in a previous paper with extirpation experiments, has been continued by transplantation experiments. The extirpation experiments showed that there are two regions near the leg which are indispensable for leg regeneration: the basal sclerites, and the membranous region extending behind the leg up to the spiracle of the next segment, called ‘leg-inducing membrane’ (LIM). The LIM is followed by ‘sclerite-inducing membrane’ (SIM) which, upon contact with sclerites, only allows formation of sclerite structures. The results of the extirpation experiments have been confirmed by transplantation experiments. When the whole leg including the basal sclerites is removed, no leg regeneration occurs. The regenerative ability can be restored by implantation of part of the basal sclerites (for instance, the trochantin), but leg regeneration takes place only when the implantation area is covered by LIM. When the sclerites are transplanted to a region which is covered by SIM only additional basal sclerites are formed. Whole sets of basal sclerites have been implanted at different distances behind the uninjured hindleg. Additional legs are regenerated only in the anterior half of the membranous field extending between the hindleg and the first abdominal segment. Thus, there is adistribution of LIM and SIM in the region of the hindleg, similar to that near the midleg. Whole sets of basal sclerites have been implanted at various sites on the dorsal or ventral surfaces of the abdomen. Legs are formed on both surfaces, but only when the transplanted sclerites contact the intersegmental membranes. This means that the intersegmental membranes of the abdomen also have leg-inducing capacities. The implantation of a trochantin into a field of LIM is followed by the development of two regenerates - a normal one at the posterior border of the field, and one with reverse anterior-posterior polarity at the anterior border. When the trochantin is transplantedtogether with the praecoxa in a similar way, only one normal regenerate is formed at theposterior margin of the trochantin. The praecoxa prevents contact of the anterior margin of the trochantin with LIM, and contact of the anterior margin of the praecoxa with LIM does not promote leg regeneration.

On a New Trematode from a Black-necked Stork, Xenorhynchns asiaticus

1962 ◽  
Vol 36 (1-2) ◽  
pp. 211-214
Author(s):  
S. Wahid
Keyword(s):  
Ventral Sucker ◽  
Large Intestine ◽  
Anterior Part ◽  
Dorsal Surface ◽  
Ventral Surface ◽  
The Body ◽  
Posterior Region ◽  
Anterior Region ◽  
Posterior Border

These trematodes were collected from the large intestine of a black-necked stork which had died in the Zoological Gardens, London. All the specimens present are damaged and there is only one piece showing the anterior part containing the head collar. It was not possible to determine the exact length of the specimens, but they are long and slender and measure at least 18 mm. in length. The body is almost uniform in width except in the regions of the ventral sucker and the testes where it is broader. The cuticle is thickly covered with spines in the anterior region of the body from the posterior border of the head collar to the posterior rim of the ventral sucker. On the dorsal surface the spines form a semicircle around the region of the ventral sucker and extend on either side of it. On the ventral surface very few spines are present on the sides of the sucker. The size of these spines varies a lot; in the anterior part they are very small, their size increasing towards the posterior region up to the end of the oesophagus from where it decreases again till the last row of spines which are very small.

Memoirs: The Morphology and Development of the Genitalia and Genital Ducts of Homoptera and Zygoptera as Shown in the Life Histories of Philaenus and Agrion

1928 ◽  
Vol s2-72 (287) ◽  
pp. 447-483
Author(s):  
C. J. GEORGE
Keyword(s):  
Anterior Part ◽  
Ejaculatory Duct ◽  
Accessory Gland ◽  
Posterior Region ◽  
Anterior Region ◽  
Vaginal Opening ◽  
Forward Region ◽  
Efferent System ◽  
Accessory Glands ◽  
The Common

1. In the male Philaenus and Agrion the vasa deferentia terminate on the ninth segment in the early stages. An ectodermal invagination from that segment joins them subsequently and thus the male gonopore is established. 2. The accessory glands develop in Philaenus male from the anterior end of the swollen extremities of the vasa deferentia and the vesiculae seminales from a still more forward region. 3. The accessory glands of the male are mesodermal in origin and not ectodermal as some authors state. 4. There is no evidence as to the existence of a ‘pair of ectodermal ejaculatory’ ducts either in Philaenus orin Agrion, and reasons are adduced to show that they do not exist at all in the higher Insecta. 5. In the female nymph of Philaenus the oviducts terminate on the seventh segment. They are subsequently joined by an ectodermal invagination from the seventh segment. The common oviduct is formed in two parts: the anterior part is derived from the posterior region of the invagination on the seventh and the posterior region is formed as a groove from the ectodermis of the eighth segment and subsequently this groove is converted into a tube. When the second part is completed it is in connexion with the invagination from the seventh and opens to the outside on the eighth segment. The ectodermal invagination from the seventh also gives rise to the spermatheca. A median accessory gland develops as an invagination from the ninth segment between the bases of the inner ovipositor lobes. A pair of accessory glands develop as paired imaginations from the anterior region of the ninth segment. 6. In the female nymph of Agrion the oviducts fuse to form a single duct and terminate in the middle of the eighth segment. Posteriorly an ectodermal invagination from the eighth segment meets this duct and lies in a position dorsal to it. Later on the ectodermal invagination develops a spermatheca dorsally and the mesodermal and the ectodermal ducts unite into one. The accessory glands develop as paired ectodermal invaginations from the anterior region of the ninth segment. 7. The female gonopore is not homologous in the different groups of insects. The vaginal opening in Orthoptera, Hymenoptera, Homoptera, Diptera, and Lepidoptera is homologous. The vaginal opening in Coleoptera is homologous with the oviducal opening of Lepidoptera, with the opening of the accessory gland of Homoptera, Hymenoptera, Diptera, Isoptera, and the opening of the spermatheca in some Orthoptera. 8. The common oviduct, being formed differently in the different groups is not homologous. The accessory organs, e. g. spermatheca, are not homologous in the different groups. 9. There is no evidence to show that the common oviduct is of paired origin. 10. The occurrence of a median accessory structure on the ninth segment which develops in the young as an invagination between the bases of the inner ovipositor lobes is very general in the higher Insecta. In some it functions as a gland, in others as a storehouse for spermatozoa. 11. The homology of the paired accessory glands is indicated. 12. The male genital ducts are not strictly homologous with those of the female. The homologue of the ejaculatory duct is the invagination from the ninth segment in the female. 13. The Odonata stand isolated in having a mesodermal region for the common oviduct and in the peculiar development of the two processes between the anterior ovipositor lobes. 14. The probable lines of evolution of the female efferent system in Insecta are indicated. The study of the development of the female efferent system indicates that the groups Orthoptera, Homoptera, Lepidoptera, and Diptera are very closely allied. Coleoptera seem to have had quite a different line of evolution from the above groups in this respect. 15. The adult Odonatan anatomy of the genital organs in the female as observed by me is in some respects different from that described by Tillyard. In conclusion I wish to express my deep sense of gratitude towards Professor Balfour-Browne and Dr. J. W. Munroe, both of whom have always been ready to help me. My colleague Mr. R. I. Nel, who is working on similar lines in this department,, has rendered me valuable help, not only in matters connected with the subject proper but also in translating difficult German references. I am also indebted to Mr. Peter Gray who helped me a good deal in translating references in Italian.

Some response characteristics of cells of the magnocellular division of the medial geniculate body of the cat

1969 ◽  
Vol 47 (10) ◽  
pp. 881-888 ◽  
Author(s):  
James A. Love ◽  
John W. Scott
Keyword(s):  
Medial Geniculate Body ◽  
Posterior Region ◽  
Single Units ◽  
Anterior Region ◽  
Sodium Pentobarbital ◽  
Experimental Conditions ◽  
Extracellular Recordings ◽  
Response Characteristics ◽  
Medial Geniculate ◽  
Somatosensory Stimuli

Extracellular recordings were made from single units in the magnocellular division of the medial geniculate body of the cat. The stimuli most frequently used were auditory clicks repeated at varying rates and intensities. Somatosensory stimuli were also used to reveal the presence of polysensory units. The response characteristics for most of the cells of the magnocellular division differed from those of the principal division under similar experimental conditions. A difference was noted between the responses obtained from animals which were anesthetized with chloralose and those anesthetized with sodium pentobarbital. It is suggested that the magnocellular division of the medial geniculate body may be divided into two regions, an anterior region which is primarily somatosensory in function and a posterior region which is primarily auditory in function.

scholarly journals An Anterior-Posterior Gradient of Refractive Index in the Ameba and Its Significance in Ameboid Movement

1958 ◽  
Vol 4 (5) ◽  
pp. 517-524 ◽  
Author(s):  
R. D. Allen ◽  
J. D. Roslansky
Keyword(s):  
Refractive Index ◽  
Organic Matter ◽  
Anterior Part ◽  
Fluid Phase ◽  
Amoeba Proteus ◽  
Contractile Vacuole ◽  
Tail Region ◽  
Anterior Border ◽  
Uniform Diameter ◽  
Anterior Posterior

Sustained locomotion in Amoeba proteus and Amoeba dubia results in the establishment of a measureable gradient of refractive index along the anterior-posterior axis of the cell, provided thickness of the specimens is kept constant by even compression under a selected coverglass supported by quartz beams of uniform diameter. The tail region of the ameba develops a higher refractive index, indicative of from 6 to 40 per cent more organic matter (expressed as protein) there than present in the front. This gradient fades on cessation of movement. The average protein concentrations in the crystal-free tails and fronts of 15 A. proteus were 3.9 and 3.4 per cent, respectively. In individual experiments, the tail-front difference ranged from one to eight times the accuracy of the method. Since the gradient of refractive index was shown not to result from extraction of water from the tail by the contractile vacuole, it was interpreted as displacement of water toward the anterior part of the cell during movement. It is suggested that contraction of the ectoplasm drives forward a "tide" of syncretic fluid, the anterior border of which is visible as the hyaline cap, which contains less than 1 per cent protein. The movement of the granular endoplasm into the hyaline cap would then complete the cycle by imbibition of the fluid tide. The theoretical positions of Pantin and of Dellinger have been combined in the proposal that ameba cytoplasm consists of a network of a contractile phase which is able to expel (by syneresis) a highly mobile fluid phase. Some other possible interpretations are discussed.

scholarly journals A highly polarized excitable cell separates sodium channels from sodium-activated potassium channels by more than a millimeter

2015 ◽  
Vol 114 (1) ◽  
pp. 520-530 ◽  
Author(s):  
Yue Ban ◽  
Benjamin E. Smith ◽  
Michael R. Markham
Keyword(s):  
Ion Channels ◽  
Three Dimensional ◽  
Electric Organ ◽  
Metabolic Cost ◽  
Great Distance ◽  
Posterior Region ◽  
Anterior Region ◽  
Cell Periphery ◽  
Spatial Coupling ◽  
Eigenmannia Virescens

The bioelectrical properties and resulting metabolic demands of electrogenic cells are determined by their morphology and the subcellular localization of ion channels. The electric organ cells (electrocytes) of the electric fish Eigenmannia virescens generate action potentials (APs) with Na+ currents >10 μA and repolarize the AP with Na+-activated K+ (KNa) channels. To better understand the role of morphology and ion channel localization in determining the metabolic cost of electrocyte APs, we used two-photon three-dimensional imaging to determine the fine cellular morphology and immunohistochemistry to localize the electrocytes' ion channels, ionotropic receptors, and Na+-K+-ATPases. We found that electrocytes are highly polarized cells ∼1.5 mm in anterior-posterior length and ∼0.6 mm in diameter, containing ∼30,000 nuclei along the cell periphery. The cell's innervated posterior region is deeply invaginated and vascularized with complex ultrastructural features, whereas the anterior region is relatively smooth. Cholinergic receptors and Na+ channels are restricted to the innervated posterior region, whereas inward rectifier K+ channels and the KNa channels that terminate the electrocyte AP are localized to the anterior region, separated by >1 mm from the only sources of Na+ influx. In other systems, submicrometer spatial coupling of Na+ and KNa channels is necessary for KNa channel activation. However, our computational simulations showed that KNa channels at a great distance from Na+ influx can still terminate the AP, suggesting that KNa channels can be activated by distant sources of Na+ influx and overturning a long-standing assumption that AP-generating ion channels are restricted to the electrocyte's posterior face.

scholarly journals Nasal Wall Oriented Implants for All-on-4 Fix-Detachable Maxillary Reconstruction

2020 ◽  
pp. 151-160
Author(s):  
Jean Uhlendorf ◽  
Carolina A. Cartelli ◽  
Larissa C. Trojan ◽  
Geninho Thomé ◽  
Marcos B. Moura
Keyword(s):  
Case Report ◽  
Dental Implants ◽  
Dental Care ◽  
Clinical Case ◽  
Posterior Region ◽  
Anterior Region ◽  
Second Step ◽  
Immediate Loading ◽  
Viable Option ◽  
Tapered Connection

Immediate loading of full-arch prostheses on dental implants in the upper arch is challenging, as the bone is of low quality and obtaining sufficient torque may be difficult. The purpose of this case report is to describe the rehabilitation of a full-arch by means of placement of four internal tapered connection tilted implants and immediate loading. A 65-year-old man sought dental care with a partially edentulous upper arch. The teeth presented mobility and were extracted. In a second step, two conventional-length implants were placed in the anterior region and two tilted and nasal wall–directed extra-long implants in the posterior region. The insertion torques of 60 N.cm allowed the installation of an immediate prosthesis (hybrid). The clinical case report suggests that the placement of tilted and extra-long implants in the paranasal bone and immediate loading may be a viable option for rehabilitation of the edentulous upper arch.

The polarity of the dental lamina in the regenerating salamander jaw

Development ◽  
1973 ◽  
Vol 30 (3) ◽  
pp. 635-646
Author(s):  
Heber T. Graver
Keyword(s):  
Normal Tissue ◽  
Ambystoma Maculatum ◽  
Dental Lamina ◽  
Reversed Polarity ◽  
The Right ◽  
Anterior Direction ◽  
Anterior Posterior

In ¼ and ½ amputated lower jaws of larval Ambystoma maculatum the dental lamina (DL) is replaced from both the anterior and posterior ends of the regenerate area, while in adult Triturus viridescens the DL is regenerated from the posterior stump tissues only. One-fourth and ½ mandibular jaw amputations were performed in such a manner that a short stump of jaw, devoid of DL, remained. Larvae exhibited a posterior regrowth of the DL, while in adults the lamina accumulated at the edge of the regenerate but did not enter the new tissue. Transplantation of a section of jaw from the left to the right side of the mandible resulted in the DL of the inserted piece having a reversed polarity in its new position. In both larval and adult forms, the DL of the transplant established connexions both anteriorly and posteriorly with lamina present. Transverse amputations through the inserted piece resulted in regeneration from the DL in the transplant in an anterior direction. Transplantation of a section of edentulous tissue into normal jaw tissue of the opposite side, or ttansplantation of a section of normal tissue into the edentulous area of the opposite side resulted in no anterior of posterior regrowth of the DL into the edentulous area. Collectively the results indicate that no anterior–posterior polarity exists in the DL of the larval salamander jaw, since regeneration can occur equally well in both directions. The DL of the adult salamander jaw exhibits an anterior–posterior polarity allowing for regrowth in an anterior direction only.

The spatial and temporal dynamics of Sax1 (CHox3) homeobox gene expression in the chick's spinal cord

Development ◽  
1994 ◽  
Vol 120 (7) ◽  
pp. 1817-1828 ◽  
Author(s):  
P. Spann ◽  
M. Ginsburg ◽  
Z. Rangini ◽  
A. Fainsod ◽  
H. Eyal-Giladi ◽  
...  
Keyword(s):  
Temporal Dynamics ◽  
Homeobox Gene ◽  
Primitive Streak ◽  
Neural Plate ◽  
Transverse Plane ◽  
Posterior Border ◽  
Anterior Border ◽  
Spatial And Temporal Dynamics ◽  
Specific Localization

Sax1 (previously CHox3) is a chicken homeobox gene belonging to the same homeobox gene family as the Drosophila NK1 and the honeybee HHO genes. Sax1 transcripts are present from stage 2 H&H until at least 5 days of embryonic development. However, specific localization of Sax1 transcripts could not be detected by in situ hybridization prior to stage 8-, when Sax1 transcripts are specifically localized in the neural plate, posterior to the hindbrain. From stages 8- to 15 H&H, Sax1 continues to be expressed only in the spinal part of the neural plate. The anterior border of Sax1 expression was found to be always in the transverse plane separating the youngest somite from the yet unsegmented mesodermal plate and to regress with similar dynamics to that of the segregation of the somites from the mesodermal plate. The posterior border of Sax1 expression coincides with the posterior end of the neural plate. In order to study a possible regulation of Sax1 expression by its neighboring tissues, several embryonic manipulation experiments were performed. These manipulations included: removal of somites, mesodermal plate or notochord and transplantation of a young ectopic notochord in the vicinity of the neural plate or transplantation of neural plate sections into the extraembryonic area. The results of these experiments revealed that the induction of the neural plate by the mesoderm has already occurred in full primitive streak embryos, after which Sax1 is autonomously regulated within the spinal part of the neural plate.

Palate Morphogenesis

Development ◽  
1979 ◽  
Vol 53 (1) ◽  
pp. 75-90
Author(s):  
Elizabeth L. Wee ◽  
Bruce S. Babiarz ◽  
Stephen Zimmerman ◽  
Ernest F. Zimmerman
Keyword(s):  
Embryo Culture ◽  
Posterior Region ◽  
Anterior Region ◽  
Serotonin Antagonists ◽  
A Cell ◽  
Pharmacologic Agents ◽  
Muscle Contractile ◽  
Contractile Cells

Previous studies have localized non-muscle contractile systems in the posterior (region 2) and the anterior (region 3) ends of mouse palates at the time of shelf movement. In order to determine whether these contractile systems function in shelf rotation, effects of pharmacologic agents have been analyzed in embryo culture. First, it was shown that the posterior end of the palate rotates before the anterior end, and its rotation in culture was proportionally greater as development of the embryo progressed. Generally, the posterior end of the palate was more easily inhibited in embryo culture than the anterior end. Serotonin at 10–−8 M to 10–−5 M was shown to significantly stimulate rotation atthe anterior end of the palate after 2 h in embryo culture. The effect on the posterior palate was less pronounced. To investigate further the role of this neurotransmitter on palate shelf rotation, serotonin antagonists were employed. Methysergide (10–−4 M) inhibited anterior shelf rotation to 12% of control values (P < 0·005), while not significantly affecting the posterior end. Ergotamine (10–−6 M) significantly inhibited the stimulation induced by 10–−5 M serotonin (P < 0·025). Cyproheptadine (10–−9 M) partially inhibited anterior and posterior shelf rotation in embryo culture. When injected into the pregnant dam, cyproheptadine partially inhibited shelf rotation and fusion. The palate was examined histologically after embryo culture. In the presence of 10–−4 M methysergide, the elongated contractile cells in region 3 at the anterior and midpalatal mesenchyme were prevented from rounding. Thus, serotonin may be regulating rotation of the anterior end of the palate by an effect on a cell-mediated process.

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