scholarly journals Development, comparative morphology and cornification of reptilian claws in relation to claws evolution in tetrapods

2009 ◽  
Vol 78 (1) ◽  
pp. 25-42 ◽  
Author(s):  
Lorenzo Alibardi
Keyword(s):  
Cell Proliferation ◽  
Tritiated Thymidine ◽  
Comparative Morphology ◽  
Ventral Side ◽  
Dorsal Side ◽  
Parallel Orientation ◽  
Mesenchymal Condensation ◽  
Keratin Layer ◽  
Matrix Zone

The development of claws in different reptiles and their cornification are analyzed using histological, ultrastructural and autoradiographic methods. Claws develop at the tip of digits in relation to the growth of the terminal phalanx and appear as modified scales. The apical epidermis of digit becomes thickened and is associated with a mesenchymal condensation or a dense mesenchyme. The dorsal side of the digit becomes the unguis while the ventral side becomes the sub-unguis. The corneous layer in the unguis is thicker than in the sub-unguis and accumulates hard-keratin while corneocytes remain separated or partially fused. Bundles of hard-keratin tend to accumulate in parallel orientation with respect to the surface and are directed toward the claw tip. The sub-unguis is formed by a softer corneous material and by a much thinner hard-keratin layer. Autoradiography after tritiated thymidine and histidine injection indicates that the growth of reptilian claws occurs along the entire epidermis of the claw. A proximal matrix zone for cell proliferation like in mammalian nails and claws is therefore absent in claws of reptiles. This observation indicates that the pattern of growth of reptilian and probably avian claws is different from that of mammals.

STUDIES ON THE EVOLUTION OF THE OPHRYOSCOLECIDAE (CILIATA: OLIGOTRICHA): II. ON THE ORIGIN OF THE HIGHER OPHRYOSCOLECIDAE

1957 ◽  
Vol 35 (1) ◽  
pp. 135-140 ◽  
Author(s):  
G. Lubinsky
Keyword(s):  
Comparative Morphology ◽  
Ventral Side ◽  
Dorsal Side ◽  
Contractile Vacuole

A comparison of the structure of Diplodinium s. str. and Entodinium of the "caudatum–laterale" group leads to the conclusion that Diplodinium originated from Entodinium as the result of torsional displacement of the nuclear apparatus, the left lateral groove, and the contractile vacuole from the dorsal side to the ventral. The ventral side of Entodinium was thus transformed into the "dorsal" side of Diplodinium The probable influence of this new conception of the comparative morphology of the Ophryoscolecidae is discussed.

scholarly journals Gravity determines the direction of nerve roots sedimentation in the lumbar spinal canal

2021 ◽  
Vol 22 (1) ◽  
Author(s):  
Jun Yang ◽  
Zhiyun Feng ◽  
Nian Chen ◽  
Zhenhua Hong ◽  
Yongyu Zheng ◽  
...  
Keyword(s):  
Lumbar Spine ◽  
Mr Imaging ◽  
Spinal Canal ◽  
Ventral Side ◽  
Lateral Position ◽  
Dorsal Side ◽  
Mr Images ◽  
Nerve Roots ◽  
Cross Sectional ◽  
Dural Sac

Abstract Objectives To investigate the role of gravity in the sedimentation of lumbar spine nerve roots using magnetic resonance (MR) imaging of various body positions. Methods A total of 56 patients, who suffered from back pain and underwent conventional supine lumbar spine MR imaging, were selected from sanmen hospital database. All the patients were called back to our hospital to perform MR imaging in prone position or lateral position. Furthermore, the sedimentation sign (SedSign) was determined based on the suspension of the nerve roots in the dural sac on cross-sectional MR images, and 31 cases were rated as positive and another 25 cases were negative. Results The mean age of negative SedSign group was significantly younger than that of positive SedSign group (51.7 ± 8.7 vs 68.4 ± 10.5, P < 0.05). The constitutions of clinical diagnosis were significantly different between patients with a positive SedSign and those with a negative SedSign (P < 0.001). Overall, nerve roots of the vast majority of patients (48/56, 85.7%) subsided to the ventral side of the dural sac on the prone MR images, although that of 8 (14.3%) patients remain stay in the dorsal side of dural sac. Nerve roots of only one patient with negative SedSign did not settle to the ventral dural sac, while this phenomenon occurred in 7 patients in positive SedSign group (4% vs 22.6%, P < 0.001). In addition, the nerve roots of all the five patients subsided to the left side of dural sac on lateral position MR images. Conclusions The nerve roots sedimentation followed the direction of gravity. Positive SedSign may be a MR sign of lumbar pathology involved the spinal canal.

Study of the development of the internal organs of the double malformations of Chironomus dorsalis by fixed and sectioned materials

Development ◽  
1970 ◽  
Vol 24 (2) ◽  
pp. 287-303
Author(s):  
Hideo Yajima
Keyword(s):  
Ventral Side ◽  
Dorsal Side ◽  
Second Step ◽  
Convex Side ◽  
Internal Organs ◽  
Flat Side ◽  
Internal Structures ◽  
Pole Cells ◽  
The One ◽  
Thoracic And Abdominal

The development of the internal structures was investigated by fixed sections of the ‘double cephalon’ and ‘double abdomen’ of Chironomus dorsalis. The cell proliferation that gives rise to ‘germ Anlage’ or embryonic rudiment begins, in the double cephalon, along the entire convex (ventral) side of the egg and, in the double abdomen, at both ends of the flat (dorsal) side. As a result, a single fused Anlage of the double cephalon appears along the entire convex side of the egg and two germ Anlagen of the double abdomen appear at both ends of the flat side. During the formation of the germ band, both the posteriormost part of the double cephalon which lies at the middle of the convex side of the egg and the anteriormost part of the double abdomen which is located at the middle of the convex side, fail to differentiate and later degenerate. In each of the duplicated heads of double cephalon, cephalic segments anterior to the first maxillary segment are formed, but the thoracic and abdominal segments are entirely missing. In each half of the double abdomen, eight abdominal segments posterior to the second abdominal segment are produced and the cephalic and thoracic segments are omitted altogether. The two pairs of mid-gut rudiment from both halves of the double cephalon are temporarily united but they break apart by the end of the blastokinesis. When the two pairs of mid-gut rudiment from both halves of the double abdomen meet, they remain fused with each other, being surrounded by the visceral mesodermal cells in the normal way, and develop into the mid-gut epithelium. In the double malformations, the pole cells are contained in only one member of the duplicated structures. The pole cells of the double cephalon develop into the tetra-nucleate state (Hasper's second step), but they fail to fuse to form tte gonad. In the double abdomen, the gonad develops in the one abdomen containing the pole colls and no replacement occurs in the sister abdomen without the pole cells. The embryonic envelopes of the double cephalon do no' retract into the interior of the embryo, while they do in the normal way in the double abdomen. The double cephalon can never hatch but the double abdon en can emerge.

Six new species of Archimonocelididae Meixner, 1938 (Platyhelminthes, Proseriata) from the Pacific, with proposal of a new genus

Zootaxa ◽  
2021 ◽  
Vol 4965 (3) ◽  
pp. 515-528
Author(s):  
MARCO CURINI-GALLETTI ◽  
ERNEST R. SCHOCKAERT
Keyword(s):  
New Species ◽  
New Genus ◽  
South Australia ◽  
Ventral Side ◽  
Copulatory Organ ◽  
Dorsal Side ◽  
The Pacific ◽  
Eastern Australia ◽  
The Pacific Ocean ◽  
The Caribbean

The genus Tajikacelis n. gen. is introduced for species of Archimonocelididae (Proseriata) characterized by the lack of atrial spines in the copulatory organ and by the opening of the seminal vesicles into the prostate vesicle at its ventral side. Six new species from the Pacific Ocean are ascribed to the new genus; they may be distinguished by features of the genital systems and the morphology of their copulatory stylets. T. tajikai n. sp. (type species of the new genus) and T. macrostomoides n. sp., both from eastern Australia, have a long tubular stylet. In T. macrostomoides n. sp., the stylet is more curved, bending to 180°, and has a narrower basis compared to that of T. tajikai n. sp. In T. artoisi n. sp., from Hawai’i, and T. nematoplanoides n. sp., from South Australia, the stylet is shaped as a truncated cone, with a broad, oblique proximal opening and a very short tubular part. T. artoisi n. sp. is distinct for the much stronger thickening of the dorsal side of the stylet, and for the different shape of the proximal opening. In T. acuta n. sp. and T. truncata n. sp., from West Panama, the tubular stylet is comparatively short; the two species differ for the shape of the distal opening, produced into a sharp spike in T. acuta n. sp., and square-ended in T. truncata n. sp.. Two species previously described in the genus Archimonocelis are transferred to Tajikacelis n. gen.: T. itoi Tajika, 1981 from Japan and T. keke Martens and Curini-Galletti, 1989 from Sulawesi (Indonesia). The taxonomic position of the problematic Archimonocelis glabrodorsata Martens and Curini-Galletti, 1989 from the Caribbean is discussed. The relationships of and within the genus Tajikacelis n. gen. are discussed and compared with recent results based on DNA studies. 

scholarly journals Atypical, ventro-ventral copulation position in aphids of the genus Stomaphis Walker, 1870 (Insecta, Hemiptera)

2014 ◽  
Vol 83 (3) ◽  
pp. 177-183 ◽  
Author(s):  
Łukasz Depa ◽  
Mariusz Kanturski ◽  
Artur Taszakowski ◽  
Karina Wieczorek
Keyword(s):  
Dominant Role ◽  
Mate Guarding ◽  
Ventral Side ◽  
Dorsal Side ◽  
Ecological Niches ◽  
Ventral Part ◽  
Large Tree ◽  
Mutualistic Relationship ◽  
Competitive Behaviour ◽  
Female Abdomen

Firm matching of genitals during copulation is of critical importance to effective insemination and thus, gene flow. During the evolution of insects, an effective position during copulation promoted higher fecundity through control over the act of mating or elimination of competitors. Usually during insect copulation, either twisting or flexing of the male abdomen occurs, and genitals remain symmetrically or asymmetrically disposed following changes in the mating position. However, it is always the dorsal side of the male genitalia that makes contact with the ventral side of female abdomen. Here we present the unusual case of a ‘belly-to-belly’ copulation, with symmetrically positioned male genitals and no twisting of the abdomen. During the mating of two species in the Stomaphis genus of large, tree dwelling aphids, the dwarfish male is attached to the underside of the female, with the ventral part of its genitals contacting the ventral part of female abdomen, and the aedeagus effectively inserted into the female genital organs. Interestingly, congeneric species do not exhibit this sort of mating, but differences in the genital plates of females, between species, may play an important role. These observations raise many questions concerning the possible dominant role of the female during mating and later, during mate guarding by male, which can lead to monandry in this generally polyandrous group of insects. It is possible that this sort of mating is either an adaptation to the competitive behaviour of other males or a consequence of the obligatory mutualistic relationship with ants, and the adaptation to specialised ecological niches enforced by this relationship. If ants do influence the mating habits of Stomaphis then it is possible that speciation in this group of insects, and phytophagous insects generally, is partially driven by their relationship with ants.

scholarly journals The changing use of the ovipositor in host shifts by ichneumonid ectoparasitoids of spiders (Hymenoptera, Ichneumonidae, Pimplinae)

Parasite ◽  
2018 ◽  
Vol 25 ◽  
pp. 17 ◽  
Author(s):  
Keizo Takasuka ◽  
Niclas R. Fritzén ◽  
Yoshihiro Tanaka ◽  
Rikio Matsumoto ◽  
Kaoru Maeto ◽  
...  
Keyword(s):  
Ventral Side ◽  
Middle Part ◽  
Dorsal Side ◽  
Physical Damage ◽  
Host Shifts ◽  
Ovipositor Morphology

Accurate egg placement into or onto a living host is an essential ability for many parasitoids, and changes in associated phenotypes, such as ovipositor morphology and behaviour, correlate with significant host shifts. Here, we report that in the ichneumonid group of koinobiont spider-ectoparasitoids (“polysphinctines”), several putatively ancestral taxa (clade I here), parasitic on ground-dwelling RTA-spiders (a group characterised by retrolateral tibial apophysis on male palpal tibiae), lay their eggs in a specific way. They tightly bend their metasoma above the spider’s cephalothorax, touching the carapace with the dorsal side of the ovipositor apically (“dorsal-press”). The egg slips out from the middle part of the ventral side of the ovipositor and moves towards its apex with the parted lower valves acting as rails. Deposition occurs as the parasitoid draws the ovipositor backwards from under the egg. Oviposition upon the tough carapace of the cephalothorax, presumably less palatable than the abdomen, is conserved in these taxa, and presumed adaptive through avoiding physical damage to the developing parasitoid. This specific way of oviposition is reversed in the putatively derived clade of polysphinctines (clade II here) parasitic on Araneoidea spiders with aerial webs, which is already known. They bend their metasoma along the spider’s abdomen, grasping the abdomen with their fore/mid legs, pressing the ventral tip of the metasoma and the lower valves of the ovipositor against the abdomen (“ventral-press”). The egg is expelled through an expansion of the lower valves, which is developed only in this clade and evident in most species, onto the softer and presumably more nutritious abdomen.

Mediators of the mitogenic action of human V1vascular vasopressin receptors

2000 ◽  
Vol 279 (5) ◽  
pp. H2529-H2539 ◽  
Author(s):  
Marc Thibonnier ◽  
Doreen M. Conarty ◽  
Christine L. Plesnicher
Keyword(s):  
Cell Cycle ◽  
Cell Proliferation ◽  
Protein Kinase ◽  
Dna Synthesis ◽  
Cell Cycle Progression ◽  
Tritiated Thymidine ◽  
Chinese Hamster ◽  
Mitogen Activated Protein Kinase ◽  
Thymidine Uptake ◽  
Mitogenic Action

Arginine vasopressin (AVP) activation of V1 vascular receptors (V1Rs) stimulates cell growth and proliferation in different tissues via cellular signaling pathways that remain to be identified. To explore the intracellular mediators of the mitogenic action of V1R, Chinese hamster ovary (CHO) cells were stably transfected with the human V1R cDNA clone we isolated previously. We assessed AVP effects on kinase activation (immunoblotting with phosphospecific antibodies), DNA synthesis (tritiated thymidine uptake), cell cycle progression (flow cytometry analysis after nuclear labeling with propidium iodide), and cell proliferation (conversion of the colorimetric reagent MTS) in the presence or absence of various pathway inhibitors. AVP stimulation of V1Rs leads to the phosphorylation of several kinases, an increase in DNA synthesis, a progression through the S and G2–M phases of the cell cycle, and an increase in cell proliferation. The mediators of the mitogenic action of V1R activation included calcium mobilization, coupling to a Gq protein, and the simultaneous and parallel activation of several kinases, mainly calcium/calmodulin-dependent kinase II, phosphatidylinositol 3 kinase, protein kinase C, and p42/p44 mitogen-activated protein kinase.

PS01.191: LAPAROSCOPIC TRANSHIATAL LOWER MEDIASTINAL LYMPHADENECTOMY FOR ESOPHAGOGASTRIC JUNCTIONAL CANCER: THE INFRACARDIAC BURSA AS A LANDMARK

2018 ◽  
Vol 31 (Supplement_1) ◽  
pp. 104-104
Author(s):  
Yasunori Kurahashi ◽  
Tatsuro Nakamura ◽  
Rie Ozawa ◽  
Yasutaka Nakanishi ◽  
Hirotaka Niwa ◽  
...  
Keyword(s):  
Lymph Node ◽  
Esophagogastric Junction ◽  
Conflicts Of Interest ◽  
Ventral Side ◽  
Dorsal Side ◽  
Node Dissection ◽  
Mediastinal Lymphadenectomy ◽  
Operating Field ◽  
Esophagogastric Junction Cancer ◽  
The Right

Abstract Background Esophagogastric junction cancer has been increasing recently. As a result, opportunities to perform transhiatal lower mediastinal lymphadenectomy are also increasing. Laparoscopic surgery is useful because the operating field of this site is too deep and narrow to perform laparotomy. But the anatomy of this area is not sufficiently clarified, and since there are few structures as landmarks, it is difficult to set the range and depth of lymph node dissection. Methods We have been verifying anatomically and embryologically the infracardiac bursa (ICB) identified as a closed lumen between the esophagus and the right crus of the diaphragm during an operation. We standardized the procedure of transhiatal lower mediastinal lymphadenectomy setting several landmarks including ICB. Results In transhiatal lower mediastinal lymphadenectomy, it is possible to do a precise lymphadenectomy by setting several landmarks including the ICB and standardizing each procedure on the ventral side, dorsal side, and both sides of the esophagus. In the case of advanced cancer which invades organs around the hiatus, it is difficult to perform routine dissection by using the infracardiac bursa or the dissectable layer. Understanding of the anatomy of this area will support the safe and precise lymphadenectomy. Conclusion In this presentation, we will show the procedure of transhiatal lower mediastinal lymphadenectomy using the ICB as a landmark. Disclosure All authors have declared no conflicts of interest.

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