The progression from earlier to later stages in maturation, e.g. a fertilized egg develops into a mature tree. It involves growth, morphogenesis (the acquisition of form and structure), and differentiation.
Stages in plant development
Zygote
Two-celled embryo
Eight-celled embryo
Globular embryo
Heart embryo
Torpedo embryo
Mature plant
Stages in animal development (sea urchin)
Zygote (fertilized egg)
Two cells
Morula (16-64 cells)
Blastula
Plant development
1. Pollen carried to stigma
2. Pollen tube grows to egg cell
3. Fertilization
4. First division into apical and basal cells
5. Apical cells form embryo, basal cells form suspensor
6. Cotyledons and root/shoot meristems form
7. Seed forms
Animal development (sea urchin)
1. Egg and sperm fuse to form zygote
2. First division into two cells
3. Subsequent divisions every 12 hours
4. Cells migrate to periphery, cavity forms - blastula stage
The plant embryo grows right from the first division, with immediate cell differentiation between apical and basal cells. The tissue is solid.
The animal embryo (sea urchin) stays spherical and does not grow during the early cell division stages.
