HLTH201 Lecture : Developmental Biology Figures 3.docx

• School: University of Waterloo
• Department: Health Studies
• Course: HLTH201
• Professor: Heidi Engelhardt

Document Summary

Amnion structure and cell movements during human gastrulation. (a) human embryo and uterine connections at day 15 of gestation. At days 14 and 15, the ingressing epiblast cells are thought to replace the hypoblast cells (which contribute to the yolk sac lining), while at day 16, the ingressing cells fan out to form the mesodermal layer. Formation of the notochord in the mouse. (a) the ventral surface a the 7. 5-day mouse embryo, seen by scanning electron microscopy. The presumptive notochord cells are the small, ciliated cells in the midline that are flanked by the larger endodermal cells of the primitive gut. The node (with its ciliated cells) is seen at the bottom. (b) the formation of the notochord by the dorsal infolding of the small, ciliated cells. Their deaths allow blood vessels to enter. (d, e) blood vessels bring in osteoblasts, which bind to the degenerating cartilaginous matrix and deposit bone matrix. (f-h)