Proximal and distal transformation during intercalary regeneration in the planarianDugesia(S)mediterranea

1985 ◽  
Vol 194 (6) ◽  
pp. 364-368 ◽  
Author(s):  
Emili Sal� ◽  
Jaume Bagu��
Keyword(s):  
Intercalary Regeneration

Intercalary regeneration in the amphibian limb and the rule of distal transformation

Development ◽  
1980 ◽  
Vol 56 (1) ◽  
pp. 201-209
Author(s):  
M. Maden
Keyword(s):  
Normal Tissue ◽  
Sole Source ◽  
Black And White ◽  
Intercalary Regeneration ◽  
Proximal Stump ◽  
Reversed Polarity

The applicability to the amphibian limb of the rule of distal transformation, which states that tissue from any level can only become more distal, has been tested during intercalary regeneration following various types of shift-level transplantation. Following the grafting of distal blastemas to proximal levels, such that part of the presumptive pattern is missing, complete limbs nevertheless formed (Series 1). That the intercalated tissue arose entirely from the stump was shown by exchanging blastemas between black and white animals. When the proximal stump was irradiated and its contribution eliminated, intercalary deletions were produced (Series II). This was not due to the inability of irradiated and normal tissue to communicate since irradiated distal blastemas grafted onto proximal stumps still stimulated intercalary regeneration (Series III). When proximal blastemas were grafted to distal levels intercalary regenerates were obtained in about 20% of the cases (Series IV) and under these circumstances the grafted blastema was the sole source of intercalated tissue. The precise structure of these intercalated elements was impossible to ascertain, but it is suggested that they might be of reversed polarity as found in insects. These results are discussed in relation to similar experiments on the insect limb.

Disruption of segmentation in a short germ insect embryo

Development ◽  
1986 ◽  
Vol 96 (1) ◽  
pp. 267-294
Author(s):  
Jane E. Mee ◽  
Vernon French
Keyword(s):  
Heat Shock ◽  
Schistocerca Gregaria ◽  
Intercalary Regeneration ◽  
Early Embryos ◽  
Pattern Regulation ◽  
Segment Pattern

A heat shock (of 15min at 48° C) given to early embryos of the locust, Schistocerca gregaria, results in localized abnormalities in the segment pattern subsequently formed. Most defects involve two consecutive segments of the thorax or abdomen, and these are analysed in detail. The abdominal defects fall into three main classes each of which involves the absence of a particular region of the segment pair and, in one class, duplication of the region which remains. The thoracic defects similarly involve absence of parts of the segments and the formation of a single limb base from which one, two, or three limbs develop. Heat shock may result in the absence of parts of segments in two distinct ways. It may interfere with the process of segmentation or it may delete parts of already formed segment primordia. These possibilities are discussed although, at present, neither can be excluded. The duplication observed in some abdominal disruptions and the formation of triple limbs indicates that the absence of parts of embryonic segments is followed by pattern regulation similar to that occurring in regeneration studies on larval segments and appendages of other insects. Two out of the three classes of abnormality can be explained in terms of intercalary regeneration restoring pattern continuity, but it is possible that discontinuities persist in the remaining class.

Intercalary regeneration around the circumference of the cockroach leg

Development ◽  
1978 ◽  
Vol 47 (1) ◽  
pp. 53-84
Author(s):  
Vernon French
Keyword(s):  
Complete Sequence ◽  
Two Dimensions ◽  
Epidermal Cells ◽  
Host Tissue ◽  
Internal Tissue ◽  
Local Growth ◽  
Intercalary Regeneration ◽  
Longitudinal Strip ◽  
Cuticular Structures ◽  
Independent Aspect

Epidermal cells from different circumferential positions around the femur of Blabera craniifer can interact to form an intercalary regenerate. Removal of a longitudinal strip of integument (cuticle plus epidermis) from any position around the circumference leads to thecut edges healing, localized growth and intercalary regeneration of the missing section ofthe circumference, so that the resulting femur is approximately normal in size and pattern of cuticular structures. Grafting a longitudinal strip of femur integument into a different circumferential position on the host femur confronts epidermal cells from different positions along both the inner and outer longitudinal graft/host junctions. In numerous different situations this results in local growth and intercalary regeneration of that section of the circumference normally separating graft and host positions, by the shorter route around the circumference. Confrontation of opposite positions results in the intercalation of either of the intervening half circumferences. In one opposite confrontation, between mid-anterior and mid-posterior, there was also a third result where graft and host healed together, provoking no intercalary regeneration. Grafts made with reversed proximal/distal polarity show that a confrontation between different circumferential positions gives the same result, regardless of the proximal/distal levels involved, hence circumferential position is an independent aspect of position on the femur. These results strongly suggest that epidermal position is not specified with respect to two transverse axes running through the epidermis and internal tissue of the leg, but that there is a continuous circular sequence of positional values running around the circumference, in the epidermis. This is analogous to but independent of the sequence previously shown by Bohn (1967) and Bulliere (1971) to run proximal/distal along a leg segment. Hence epidermal position on the femur is specified in two dimensions and can be represented in terms of the French, Bryant & Bryant (1976) polar co-ordinate model. Interactions along the edges of the strip-grafts conform to the Shortest Intercalation Rule (French et al. 1976). At the proximal and distal ends of strip-grafts intercalation restores normal sequences of positional values where possible. However, where the graft, together with the intercalary regenerates formed at the longitudinal graft/host junctions and the adjacent host tissue formed a complete sequence of circular values, then a supernumerary distal regenerate was formed, in agreement with the Complete Circle Rule of French et al. (1976). The problem of generating a continuous circular sequence of positional values by one or more circumferential gradients, is briefly discussed.

Intercalary regeneration in planarians

2003 ◽  
Vol 226 (2) ◽  
pp. 308-316 ◽  
Author(s):  
K. Agata ◽  
T. Tanaka ◽  
C. Kobayashi ◽  
K. Kato ◽  
Y. Saitoh
Keyword(s):  
Intercalary Regeneration
Sign in / Sign up

Export Citation Format

Share Document