Differentiation of lens- and Iris-like tissue in explants of the anterior part of the frog neural plate

1972 ◽  
Vol 171 (1) ◽  
pp. 1-16 ◽  
Author(s):  
Olga A. Hoperskaya
Keyword(s):  
Anterior Part ◽  
Neural Plate

scholarly journals Segregating expression domains of two goosecoid genes during the transition from gastrulation to neurulation in chick embryos

Development ◽  
1997 ◽  
Vol 124 (8) ◽  
pp. 1443-1452 ◽  
Author(s):  
L. Lemaire ◽  
T. Roeser ◽  
J.C. Izpisua-Belmonte ◽  
M. Kessel
Keyword(s):  
Posterior Margin ◽  
Anterior Part ◽  
Primitive Streak ◽  
Neural Plate ◽  
Chick Embryos ◽  
Positive Part ◽  
Full Extension ◽  
Isolation And Characterization ◽  
Chick Embryogenesis

We report the isolation and characterization of a chicken gene, GSX, containing a homeobox similar to that of the goosecoid gene. The structure of the GSX gene and the deduced GSX protein are highly related to the previously described goosecoid gene. The two homeodomains are 74% identical. In the first few hours of chick embryogenesis, the expression pattern of GSX is similar to GSC, in the posterior margin of the embryo and the young primitive streak. Later during gastrulation, expression of the two genes segregate. GSC is expressed in the anterior part of the primitive streak, then in the node, and finally in the pre-chordal plate. GSX is expressed in the primitive streak excluding the node, and then demarcating the early neural plate around the anterior streak and overlying the pre-chordal plate. We demonstrate that the GSX-positive part of the primitive streak induces gastrulation, while the GSC-expressing part induces neurulation. After full extension of the streak, the fate of cells now characterized by GSX is to undergo neurulation, while those expressing GSC undergo gastrulation. We discuss the effect of a duplicated basic goosecoid identity for the generation of a chordate nervous system in ontogeny and phylogeny.

scholarly journals Induction by the Primitive Streak and its Derivatives in the Chick

1933 ◽  
Vol 10 (1) ◽  
pp. 38-46 ◽  
Author(s):  
C. H. WADDINGTON
Keyword(s):  
Anterior Part ◽  
Primitive Streak ◽  
Neural Plate ◽  
Embryonic Axis ◽  
Host Embryo

1. Specimens are described which demonstrate the induction of neural plateby (a) the mesodermal part of the primitive streak, (b) the head process and sinus rhomboidalis, and (c) neural plate. 2. The neural plate which was induced by the mesodermal part of the primitive streak was in reversed orientation as regards the host embryo. Thus the orientation of the embryo must be already fixed in the mesodermal part of the streak, and must in this case have overcome any influence which the host may be able to exert. 3. The same embryo was more complete than indicated by the presumptive fate of the tissue which induced it, whence it is concluded that the chick organiser,like the amphibian, shows a tendency to complete itself, and to this extent behaves like part of a harmonious equipotential system. 4. Grafts of the anterior part of the embryonic axis (head process and neuralplate) into the anterior part of the host blastoderm, have induced structures which in nearly all cases give indications of being heads. Inductions by posterior parts of the axis (sinus rhomboidalis) have never given such indications. 5. Grafts of the notochord have not, as yet, given satisfactory inductions.

Studies on Regional Specificity Within the Organization Centre of Urodeles

1950 ◽  
Vol 27 (2) ◽  
pp. 126-144
Author(s):  
C. H. WADDINGTON ◽  
T. YAO
Keyword(s):  
Spina Bifida ◽  
Anterior Part ◽  
Organizer Region ◽  
Neural Plate ◽  
Normal Embryo ◽  
Median Part ◽  
Regional Specificity ◽  
Spatio Temporal ◽  
Regional Character ◽  
Organization Centre

1. In young gastrulae of Triton alpestris the median part of the organization centre immediately in front of the blastopore was excised and replaced after reversal of its anterior-posterior axis. Completely normal embryos developed in many cases, but in others there was some degree of microcephaly or spina bifida. 2. Similar normal embryos can develop after exchange of the anterior and posterior regions of the organizer, either with normal or reversed orientation. 3. The spina bifida which frequently appears is a consequence of the impediment offered by the graft to the normal gastrulation movements. 4. Microcephaly may also result if the presence of the graft prevents the proper development of the anterior part of the archenteron roof. 5. It may also be caused when the posterior organizer region is brought into the anterior region, if the host fails to convert it into anterior material. This occurs the more frequently the older the grafted posterior material is. 6. Even at the end of gastrulation (slit yolk-plug stage) the regional character of the archenteron roof is not finally determined. A fairly normal embryo (with over-thick mesoderm) may develop if an extra archenteron roof is added with reversed orientation between the normal archenteron roof and the presumptive neural plate. 7. The determination of the regional structure of the archenteron roof and the neural plate is discussed. Attention is drawn to the spatio-temporal factors involved in the production and diffusion of the evocator with the dynamic system of the gastrulating egg.

Differentiation capacities of the prospective tail somite region of the neural plate in the embryos of Ambystoma mexicanum

Development ◽  
1969 ◽  
Vol 22 (1) ◽  
pp. 1-14
Author(s):  
I. A. Niazi
Keyword(s):  
Anterior Part ◽  
Posterior Part ◽  
Neural Plate ◽  
Ambystoma Mexicanum ◽  
Trunk Region ◽  
Amphibian Embryos ◽  
The Future ◽  
Transient Contact ◽  
Posterior Trunk ◽  
Neurula Stage

The hind part of the neural plate in amphibian embryos has a mesodermal significance although it occupies an ectodermal position till late neurula stage. In anurans it gives rise to the posterior tail somites (Smithberg, 1954) and in urodeles the somites of the posterior trunk region and of the entire tail together with several other mesodermal structures (Bijtel, 1931; Nakamura, 1938; Aufsess, 1941; Spofford, 1945; Chuang, 1947; Ford, 1949). Presence of mesoderm in the neural plate is an interesting developmental problem. During normal gastrulation this region is at first underlaid by the future anterior part of the archenteric roof which exerts a neuralizing inductive influence. It is only later that the posterior part of the notochord with its mesodermalizing influence comes to lie under it. According to Eyal-Giladi (1954), who worked on gastrula stages of the Axolotl, even a short and transient contact of the invaginating archenteric roof with the overlying ectoderm produces archencephalic induction in the latter.

Fine structure of the rectal papillae of the oriental fruuit fly, Dacus dorsalis Hendel (Tephritidae, Diptera Insecta)

1990 ◽  
Vol 48 (3) ◽  
pp. 498-499
Author(s):  
Len Wen-Yung ◽  
Mei-Jung Lin
Keyword(s):  
Fine Structure ◽  
Cell Membrane ◽  
Intercellular Space ◽  
Anterior Part ◽  
Apical Cell ◽  
Posterior Part ◽  
Apical Cell Membrane ◽  
Dacus Dorsalis ◽  
Radial Cell ◽  
Circular Base

Four cone-shaped rectal papillae locate at the anterior part of the rectum in Dacus dorsalis fly. The circular base of the papilla protrudes into the haemolymph (Fig. 1,2) and the rest cone-shaped tip (Fig. 2) inserts in the rectal lumen. The base is surrounded with the cuticle (Fig. 5). The internal structure of the rectal papilla (Fig. 3) comprises of the cortex with the columnar epithelial cells and a rod-shaped medulla. Between them, there is the infundibular space and many trabeculae connect each other. Several tracheae insert into the papilla through the top of the medulla, then run into the cortical epithelium and locate in the intercellular space. The intercellular sinuses distribute in the posterior part of the rectal papilla.The cortex of the base divides into about thirty segments. Between segments there is a radial cell (Fig. 4). Under the cuticle, the apical cell membrane of the cortical epithelium is folded into a regular border of leaflets (Fig. 5).

A remarkable pogonophoran from a desalted shallow near the mouth of the Yenisey River in the Kara Sea, with the description of a new species of the genus Galathealinum (Annelida: Pogonophora: Frenulata)

2020 ◽  
Vol 29 (1) ◽  
pp. 138-154
Author(s):  
R.V. Smirnov ◽  
O.V. Zaitseva ◽  
A.A. Vedenin
Keyword(s):  
New Species ◽  
Arctic Ocean ◽  
Anterior Part ◽  
Morphological Characters ◽  
Kara Sea ◽  
The Arctic ◽  
External Layer ◽  
The Arctic Ocean ◽  
A New Species ◽  
Unusual Finding

A new species of Pogonophora obtained from one station at a depth of 25 m from near the Dikson Island in the Kara Sea is described. Galathealinum karaense sp. nov. is one of the largest pogonophorans, the first known representative of the rare genus Galathealinum Kirkegaard, 1956 in the Eurasian part of the Arctic Ocean and a highly unusual finding for the desalted shallow of the Yenisey Gulf. Several characters occurring in the new species are rare or unique among the congeners: under-developed, hardly discernible frills on the tube segments, extremely thin felted fibres in the external layer of the tube, and very faintly separated papillae in the anterior part of the trunk. Morphological characters useful in distinguishing species within the genus Galathealinum are defined and summarised in a table. Diagnosis of the genus Galathealinum is emended and supplemented by new characters. Additionally, three taxonomic keys are provided to the species of Galathealinum and to the known species of the Arctic pogonophorans using either animals or their empty tubes only, with the brief zoogeographical information on each Arctic species.

MECHANISM OF VARIABILITY REDUCTION IN THE SYSTEM OF SKELETAL MUSCLE MANAGEMENT IN ATHLETES ACCORDING TO THE PRINCIPLE OF FUNCTIONAL SYNERGY FORMATION

2019 ◽  
pp. 95-104
Author(s):  
S.A. Moiseev
Keyword(s):  
Skeletal Muscle ◽  
Skeletal Muscles ◽  
Anterior Part ◽  
Movement Control ◽  
Small Variation ◽  
Deltoid Muscle ◽  
Simultaneous Recording ◽  
Muscle Synergy ◽  
Statistical Parameters ◽  
Left Limb

The question of physiological function variability is of great theoretical interest, since it is a part of the theory of human voluntary movement control. The skeletal muscle control system should probably have a mechanism to reduce or limit the range of its possible variations. Presumably, the organization of the motor system elements according to the principle of muscular synergy is of such a nature. The objective of the work is to study variations and signs of the coordinated bioelectric activity of skeletal muscles in one of the resulting archery phases. Materials and Methods. The study enrolled 5 highly qualified sportsmen (Master of Sport, International Master of Sport). Archers shot 10 series of 3 shots, target distance 18 m, indoors. Simultaneous recording of electrical activity of 12 skeletal muscles of the upper limb girdle and a 3D video sequence was made. The authors analyzed indicators of distribution, descriptive and variation statistics for grouped data. Multiple regression analysis was used to identify signs of consistent muscle activity. Results. Variability magnitudes, characterized by statistical parameters, established for the turn-off-peak characteristics of various muscles, did not have an explicit dependence. Muscles with relatively high scattering parameters in terms of the EMG average amplitude could have a small variation in the average number of EMG turns. The radial flexor of the left hand wrist was a part of muscular synergy in 90 % of cases, the anterior part of the left limb deltoid muscle – in 80 % of cases, the lower and upper beams of the right and left cowl muscle – in 70 % of cases. Other muscles under consideration were their part in less than 60 % of cases. Conclusion. The system of skeletal muscles that are actively involved in the resulting phases of precision movement can be controlled according to the mechanism of functional synergy formation, which probably helps to reduce the range of possible variations in the parameters of muscle electroactivity. Keywords: variability, archery, electromyography, coordination structure, muscle synergy. Вопрос вариативности физиологических функций представляет интерес в теоретическом плане, поскольку является частью теории управления произвольными движениями человека. Система управления скелетными мышцами, вероятно, должна иметь механизм, позволяющий сократить или ограничить диапазон возможных ее вариаций. Таковым, предположительно, является организация элементов моторной системы по принципу мышечных синергий. Цель работы – изучение вариаций и признаков согласованной биоэлектрической активности скелетных мышц в одной из результирующих фаз выстрела из лука. Материалы и методы. В исследованиях приняли участие 5 высококвалифицированных спортсменов (МС, МСМК). Лучники выполняли 10 серий по 3 выстрела с дистанции 18 м в крытом помещении. Производилась синхронная регистрация электрической активности 12 скелетных мышц верхнего плечевого пояса и 3D-видеоряда. Анализировались показатели распределения, описательной и вариационной статистики для сгруппированных данных. Для выявления признаков согласованной активности мышц применялся множественный регрессионный анализ. Результаты. Величины вариативности, характеризуемые статистическими параметрами, установленные для турн-аплитудных характеристик различных мышц, не имели явной зависимости. Мышцы, имеющие относительно высокие параметры разброса значений по показателю средней амплитуды ЭМГ, могли иметь небольшую вариативность среднего числа турнов ЭМГ. Лучевой сгибатель кисти левой руки являлся частью мышечной синергии в 90 % случаев, передняя часть дельтовидной мышцы левой конечности – в 80 %, нижние и верхние пучки трапециевидной мышцы правой и левой сторон – в 70 %. Другие исследуемые мышцы являлись их частью в менее чем 60 % случаев. Выводы. Управление системой скелетных мышц, принимающих активное участие в реализации одной из результирующих фаз точностного движения, может осуществляться по механизму образования функциональных синергий, что, вероятно, способствует снижению диапазона возможных вариаций параметров электроактивности мышц. Ключевые слова: вариативность, стрельба из лука, электромиография, координационная структура, мышечные синергии.

Possibility of simultaneous transposition of segments of the pectoralis major muscle to restore flexion in the shoulder and elbow joints (clinical observation)

MedAlliance ◽  
2020 ◽  
Vol 8 (1) ◽  
pp. 61-68
Keyword(s):  
Anterior Part ◽  
Pectoralis Major Muscle ◽  
Elbow Flexion ◽  
Functional Results ◽  
Proximal Part ◽  
Deltoid Muscle ◽  
Pectoralis Major ◽  
Orthopedic Surgeons ◽  
Active Function ◽  
Head Neck

The pectoralis major is a widely used muscle in reconstruction surgery for replacement soft tissue defects of a head, neck, thorax, upper limbs and restoration of muscle active function. The peculiarities of anatomy of the pectoralis major makes it possible to divide the muscle into several segments with their own innervations and supply and use them independently from each other. This article describes the anatomy of the pectoralis major and the opportunity for clinical applications of different segments of this muscle. The authors demonstrate the result of the restoration of shoulder and elbow flexion in a patient with arthrogryposis due to simultaneous transfer of the proximal part of pectoralis major to the anterior part of the deltoid muscle and the distal part of pectoralis major to the biceps with good functional results. The article will be useful for plastic surgeons, orthopedic surgeons and physiotherapists.

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