Correlative changes during early morphogenesis of the sacroiliac complex in squamate reptiles

Citation
Vg. Borkhvardt et Yb. Malashichev, Correlative changes during early morphogenesis of the sacroiliac complex in squamate reptiles, ANN ANATOMY, 182(5), 2000, pp. 439-444
Citations number
16
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Experimental Biology
Journal title
ANNALS OF ANATOMY-ANATOMISCHER ANZEIGER
ISSN journal
0940-9602 → ACNP
Volume
182
Issue
5
Year of publication
2000
Pages
439 - 444
Database
ISI
SICI code
0940-9602(200009)182:5<439:CCDEMO>2.0.ZU;2-6
Abstract
We tested the limb bud" hypothesis, which explains morphogenetic mechanisms of the formation of the sacroiliac skeletal complex in tetrapods. The hypo thesis assumes that: 1) the destruction of the embryonal sacral myomeres an d the appearance in their place of a sacral gap filled in with mesenchymal cells favor the development of the sacroiliac complex; and 2) the destructi on of myomeres takes place under the influence of limb buds. We studied ser ial hystological sections of embryos from squamate reptiles with large limb buds (sand lizard, Lacerta agilis L.), small and short-living limb buds (s low worm, Anguis fragilis I,.) and without limb buds (adder, Vipera berus ( L.)). In embryos of the sand lizard, the hypaxial part of the second sacral myomere degenerated, whereas that of the first one survived in its cranial part. Thus, a large sacral gap was formed where two sacral ribs expanded l ater. They stretched in a manner similar to the sacral gap across the longi tudinal axis of the body, the large ilium lying opposite them. In embryos o f the slow worm, the sacral gap was of reduced size and was significantly b eveled caudally. The only sacral rib and the upper part of the ilium, which lie within the sacral gap, were beveled in the same manner. In embryos of the adder, myomere destruction was not observed, and sacral ribs and the pe lvic girdle did not arise. The obtained results generally agree with the li mb bud hypothesis; therefore, it can be said that tetrapods possess a simpl e and effective morphogenetic mechanism by which the hind limbs create thei r own support on the axial skeleton.