Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Blastula – Structure and Fate Map V 1 D A First Steps • “Bottle cells” form at the vegetal most side of the organizer by apical constriction. V D Vg Apical constriction and invagination of Bottle Cells Invagination: “the infolding of a sheet of cells". 2 Organizer region • The bottle cells invaginate into the interior of the embryo making a dimple. A Next Step • Endodermal and marginal dorsal cell layers start to involute into the blastocoel. V D Vg Organizer region Involution – of Endodermal and marginal dorsal cell “A type of cell movement during gastrulation by which an expanding epithelium turns over on itself and continues to spread in the opposite direction along its basal margin". 1 3 2 Blastopore Formation • The surface endodermal cells and the deep mesodermal cells continue to involute and move towards the animal side. • At the site of entry an opening forms – the blastopore. Extension and Archenteron Formation • The involuting layers elongate by convergent extension. 4 Convergent Extension “cell movement resulting in tissue elongation via intercalation. Two or more rows of cells intercalate, but the intercalation is highly directional. Cells converge by intercalating perpendicular to the axis of extension, resulting in the overall extension of the tissue in a preferred direction” . Extension and Archenteron Formation • The involuting layers elongate by convergent extension. • The archenteron forms between the involuting endoderm and the vegetal inner endoderm. 5 Extension and Archenteron Formation • The involuting layers elongate by convergent extension. • The archenteron forms between the involuting endoderm and the vegetal inner endoderm. • The animal cells extend to cover the space left using epiboly. Epiboly - of the animal cells “over the ball", usually the growth of epidermal ectoderm to cover the surface of the embryo during gastrulation. 6 Blastopore Extension • The blastopore extends laterally and ventrally. Dorsal blastopore lip Fate Map at Onset of Gastrulation 7 Gastrulation Progression Apical constriction and invagination Involution Convergent extension and epiboly Gastrulation Progression 8 פתרון עבודת הכנה לתרגיל Xenopus Gastrulation – 5 על סמך הניסוי של Vogtמהמאה ה ) 19עמוד 12במהדורה שביעית של Gilbert ” ( “Developmental Biologyובהתאם לתהליך תנועות התאים לאורך הגסטרולציה ב ,Xenopus ציינו את מיקומם החדש של התאים השונים בסוף הגסטרולציה ).(B Lateral view Dorsal view 6 7 8 9 10 11 V D 6 Dorsal lip Mesoderm 8 9 1 7 6 3 5 4 11 8 9 10 Anus 3 Ectoderm V 7 2 D Archenteron D 5 4 2 1 A 4 Head 10 11 Endoderm 3 4 5 10 11 B V 9