Regeneration from half lower arms in the axolotl

Development ◽  
1986 ◽  
Vol 95 (1) ◽  
pp. 247-260
Author(s):  
Peter Wigmore
Keyword(s):  
Posterior Half ◽  
Upper Arm ◽  
Digit Number ◽  
Single Digit ◽  
Skeletal Structures ◽  
Anterior Dorsal ◽  
Anterior Half ◽  
Ventral Muscle ◽  
Posterior Anterior

A technique involving grafting of pieces of skin from the head onto the limb in order to isolate halves of the limb is described. This technique was used to isolate posterior, anterior, dorsal and ventral halves of the lower arm. All halves produced regenerates but no part of the limb was able to produce a high proportion of regenerates with a complete pattern of skeletal structures. Posterior half stumps regenerated limbs with a mean digit number of 2.7 and had a normal dorsoventral muscle pattern. Anterior half stumps produced a high proportion of single-digit regenerates and had a mean digit number of 1.3. Dorsal and ventral half stumps regenerated limbs with a mean digit number of 2.8 and 2.3 respectively. Hypomorphic regenerates from dorsal and ventral half stumps often had only dorsal or ventral muscle. These results are in contrast to those from the upper arm (Wigmore & Holder, 1985) where a complete skeletal and muscular pattern regenerated from posterior and dorsal halves and hypomorphic regenerates were obtained from anterior and ventral half limbs.

Regeneration from isolated half limbs in the upper arm of the axolotl

Development ◽  
1985 ◽  
Vol 89 (1) ◽  
pp. 333-347
Author(s):  
Peter Wigmore ◽  
Nigel Holder
Keyword(s):  
Regional Differences ◽  
Dorsal Side ◽  
Posterior Half ◽  
Upper Arm ◽  
Digit Number ◽  
Dorsoventral Axis ◽  
Anterior Dorsal ◽  
Posterior Anterior

A technique enabling the isolation of half limb stumps using strips of skin from the head is described. Using this technique posterior, anterior, dorsal and ventral halves of the upper arms of axolotls were constructed. All halves produced regenerates and regional differences were shown in the regenerative and regulative abilites of the different halves. Posterior half stumps regenerated limbs with a mean digit number of 3·9 and had a normal dorsoventral muscle pattern. Anterior halves produced hypomorphic limbs with a mean digit number of 1·2 while dorsal and ventral halves produced an average of 3·8 and 2·6 respectively. Regenerates from dorsal half stumps had a normal dorsoventral axis but the majority of those from ventral halves were either double ventral or had little muscle on the dorsal side of the limb.

The effect of replacing different regions of limb skin with head skin on regeneration in the axolotl

Development ◽  
1986 ◽  
Vol 98 (1) ◽  
pp. 237-249
Author(s):  
Peter Wigmore ◽  
Nigel Holder
Keyword(s):  
Spatial Organization ◽  
Normal Pattern ◽  
Upper Arm ◽  
Single Digit ◽  
Anteroposterior Axis ◽  
Skeletal Pattern ◽  
Ventral Skin ◽  
Ventral Muscle

Head skin was used to replace different halves of limb skin from the upper and lower arms of axolotls. Replacement of upper arm posterior skin caused the regeneration of a high proportion of single-digit limbs while replacement of dorsal, ventral or anterior skin caused only minor defects to the normal skeletal pattern. When dorsal or ventral skin was replaced, however, regenerates often lacked dorsal or ventral muscle. Results from the lower arm were different in that replacement of any half of limb skin failed to cause defects either in the skeletal or muscular pattern. These results are used in conjunction with previous work (Wigmore & Holder, 1985; Wigmore, 1986) to suggest that posterior skin is essential for regeneration of the anteroposterior axis and dorsal and ventral skin is necessary for the differentiation of the muscle pattern in regenerates from the upper arm. In the lower arm no localized region of skin appears to be essential for regeneration of the normal pattern and the patterning mechanism may have a different spatial organization.

The Results of Experimental Measurements of the Effects of Floating Floor Washers

2016 ◽  
Vol 820 ◽  
pp. 454-459
Author(s):  
Dušan Dlhý ◽  
Peter Tomašovič ◽  
Peter Petrák
Keyword(s):  
Noise Level ◽  
General Public ◽  
Experimental Measurements ◽  
Digit Number ◽  
Single Digit ◽  
Impact Noise

Many manufacturers of spring washers laid under floating floors express the effect of the reduction in a normalized impact noise level as a single digit number ∆L(dB) without defining the composition of the ceiling construction and wear layer, where the reduction in impact noise has occurred. This expression represents the quality and efficiency of washers for general public as well as for experts (architects, designers), which however, cannot be achieved by in situ (on site) measurements.

Multi-digit Number Processing

2014 ◽  
Author(s):  
Hans-Christoph Nuerk ◽  
Korbinian Moeller ◽  
Klaus Willmes
Keyword(s):  
Numerical Cognition ◽  
Distance Effect ◽  
Number Processing ◽  
Place Value ◽  
Digit Number ◽  
Single Digit ◽  
Numerical Development ◽  
Conceptual Distinction ◽  
Place Identification

Only recently the focus in numerical cognition research has considered multi-digit number processing as a relatively new and yet understudied domain in mathematical cognition. In this chapter: (i) we argue that single-digit number processing is not sufficient to understand multi-digit number processing; (ii) provide an overview on which representations and effects have been investigated for multi-digit numbers; (iii) suggest a conceptual distinction between place-identification, place-value activation, and place-value computation; (iv) identify language influences on multi-digit number processing along that conceptual distinction; and (v) argue that for numerical development indices of multi-digit number processing may be more suitable predictors of later arithmetical performance than classical single-digit measure such as the distance effect or non-numerical variables (e.g., working memory). In the final section, we summarize the important issues in multi-digit number processing, outline future directions and try to encourage readers to contribute to a new, exciting, yet understudied domain of numerical cognition.

scholarly journals Strategies Used by Grade 6 Learners in the Multiplication of Whole Numbers in Five Selected Primary Schools in the Kavango East and West Regions

2020 ◽  
Vol 13 (3) ◽  
pp. 65
Author(s):  
Alex Mbonabi ILUKENA ◽  
Christina Nyarai UTETE ◽  
Chosi KASANDA
Keyword(s):  
Primary Schools ◽  
Traditional Method ◽  
Mathematics Curriculum ◽  
Ministry Of Education ◽  
Digit Number ◽  
Single Digit ◽  
Whole Numbers ◽  
Paper And Pencil ◽  
East And West ◽  
Short Method

This research paper reports strategies used by Grade 6 learners in multiplying whole numbers in five selected primary schools in Kavango East and West regions. A total of 200 learners’ mathematics exercise books were analysed in order to identify the commonly used strategies by learners in multiplying whole numbers. A total of ten teachers teaching grade 6 mathematics were also requested to complete a questionnaire which required them to indicate the strategies that they employed in class when teaching multiplication of whole numbers. The teachers indicated that they used a variety of strategies including repeated addition, complete-number (Including doubling), partitioning and compensation to teach multiplication of whole numbers. The results also disclosed that the majority of the learners’ mathematics exercise books reflected the use of the traditional method of repeated addition contrary to the teachers’ claims. It was also found that a few of the learners used other strategies such as long method, short method and learner “invented” strategies. Additionally, the mathematics curriculum for upper primary learners (Grade 4-7 mathematics syllabus) requires learners to use paper and pencil algorithms to carry out multiplication of whole numbers without calculators (Ministry of Education, Arts & Culture [MoEAC], 2015, p. 2). However, at Grade 6, learners were expected to use paper and pencil algorithms to multiply numbers within the range 0-100000. Analysis of the learners’ exercise books indicated that the majority were not able to multiply a two digit by a single digit, a two digit by a two digit and a three digit by a two digit number.

scholarly journals Evidence of five digits in embryonic horses and developmental stabilization of tetrapod digit number

2020 ◽  
Vol 287 (1920) ◽  
pp. 20192756
Author(s):  
Kathryn D. Kavanagh ◽  
C. Scott Bailey ◽  
Karen E. Sears
Keyword(s):  
Extreme Case ◽  
Developmental Stability ◽  
Digit Number ◽  
Single Digit ◽  
Developmental Mechanisms ◽  
Organ Systems

Previous work comparing the developmental mechanisms involved in digit reduction in horses with other mammals reported that horses have only a ‘single digit', with two flanking metapodials identified as remnants of digit II and IV. Here we show that early Equus embryos go through a stage with five digit condensations, and that the flanking splint metapodials result from fusions of the two anterior digits I and II and the two posterior digits IV and V, in a striking parallel between ontogeny and phylogeny. Given that even this most extreme case of digit reduction exhibits primary pentadactyly, we re-examined the initial stages of digit condensation of all digit-reduced tetrapods where data are available and found that in all cases, five or four digits initiate (four with digit I missing). The persistent pentadactyl initiation in the horse and other digit-reduced modern taxa underscores a durable developmental stability at the initiation of digits. The digit evodevo model may help illuminate the biological circumstances under which organ systems become highly stabilized versus highly plastic.

Retinoic acid induces a pattern of digits in anterior half wing buds that lack the zone of polarizing activity

Development ◽  
1989 ◽  
Vol 107 (4) ◽  
pp. 863-867 ◽  
Author(s):  
G. Eichele
Keyword(s):  
Retinoic Acid ◽  
Cell Fate ◽  
Anterior Margin ◽  
Limb Bud ◽  
Posterior Half ◽  
Anterior Half ◽  
Zone Of Polarizing Activity

Wing buds whose posterior half is excised, develop into wings lacking distal structures. However, such experimentally generated preaxial half wing buds can be rescued by implanting a retinoic-acid-releasing bead at their anterior margin. The polarity of the pattern that originates from preaxial half wing buds is reversed. For example, instead of a 234 digit pattern typical for normal wings, the order of digits is 432. This result implies that retinoic acid has the capacity to reprogram anterior limb bud tissue, and that the resulting change in cell fate does not depend on the presence of posterior tissue regions such as the zone of polarizing activity (ZPA).

The development of hepatogenic potency in the endoderm of quail embryos

Development ◽  
1979 ◽  
Vol 52 (1) ◽  
pp. 49-62
Author(s):  
Sumiko Fukuda
Keyword(s):  
Digestive Tract ◽  
The Other ◽  
Chick Embryos ◽  
Posterior Half ◽  
Coelomic Cavity ◽  
Somite Stage ◽  
Anterior Half ◽  
Other Hand ◽  
Cardiac Region ◽  
Cardiac Mesenchyme

Hepatogenic potency of the endoderm is detectable in the anterior half of the endoderm of quail embryos older than 2-somite stage when endodermal fragments are cultured with or without heterologous chick mesenchymes, in the coelomic cavity of 3-day chick embryos. On the other hand, the posterior half of the endoderm never has hepatogenic potency. The hepatogenic potency of the endoderm is gradually stabilised with increasing age. However, expression of hepatogenesis can be affected when the endoderm is associated with inductively active digestive tract mesenchymes. Mesenchyme taken from the presumptive cardiac region (‘cardiac’ mesenchyme) of chick embryos is necessary for the uncommitted anterior endoderm to acquire hepatogenic potency, and this effect is specific for the ‘cardiac’ mesenchyme. The ‘cardiac’ mesenchyme, however, fails to induce hepatic epithelium in the allantoic endoderm, which can differentiate heterotypically when cultured in combination with digestive tract mesenchymes. The evidence presented in this study suggests that the effect of ‘cardiac’ mesenchyme on the acquisition of hepatogenic potency in the endoderm is limited.

Gross anatomical features of the sternum of green-winged macaw (Ara Chloroptera)

2015 ◽  
Vol 49 (6) ◽  
Author(s):  
A. R. Sreeranjini ◽  
N. Ashok ◽  
V. R. Indu ◽  
K. M. Lucy ◽  
S. Maya ◽  
...  
Keyword(s):  
Anterior Extremity ◽  
Dorsal Surface ◽  
Ventral Surface ◽  
Morphological Features ◽  
Posterior Border ◽  
Posterior Half ◽  
Lateral Border ◽  
Convex Surfaces ◽  
Anatomical Features ◽  
Anterior Half

The present study was conducted on the sternum of an eight year old, male Green-winged Macaw. The sternum was quadrilateral with dorsal concave and ventral convex surfaces and four borders. The dorsal surface presented numerous pneumatic foramina. The ventral surface furnished a large, boat shaped keel. The anterior extremity showed two facets for coracoid. The anterior and posterior borders were convex. The lateral border on either side presented six costal facets. Two distinct oval foramina were seen near the posterior border. Craniolateral processes were short and stump-like. Caudolateral processes fused with the median trabecula on either side. The rostrum was distinct. The morphological features of the sternum of Green-winged Macaw conformed to that of flying group of birds. It was almost similar to that of goose in its anterior half and to that of pigeon in its posterior half.

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