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This topic delves into the stages of embryonic development, from fertilization to gastrulation, highlighting key processes and structures such as cleavage, morula, blastula, and gastrula. Through the description of external and internal fertilization, types of organisms involved, and the differentiation of germ layers, students will gain a comprehensive understanding of how complex organisms develop from a single cell.
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Topic: Reproduction Aim: Describe the stages of embryonic development. Do Now: • Describe the process of fertilization. • Describe the types of organisms that use external fertilization. • Describe the types of organisms that use internal fertilization. HW: Work on your science fair board. CL Mitosis and Asexual Repro due Tuesday, February 24th
1. How does a zygote move through the oviduct? • Smooth muscle contractions • Cilia lining the oviduct
2. Identify the process in which the zygote undergoes mitotic cell division. • Cleavage
Observe what is happening to the size of the cells as cleavage occurs.
Cleavage in Clam embryonic development Observe what is happening to the size of the cells as cleavage occurs.
Are the cells growing? - NO CELL GROWTH
1 2 3 4 5 Identify the numbers that represent cleavage.
3. Identify the structure that forms as a result of cleavage. • Morula Occurs 3 days after fertilization.
4. Describe a morula. • Solid ball of cells Consists of 16 cells
5. Identify the structure that forms AFTER the morula and describe its structure. • Blastula • Hollow ball of cells Identify the blastula. Support your answer.
1 2 3 4 5 Morula Blastula • Identify the morula. • Identify the blastula.
Zygote Cleavge Cleavage This takes about 6–7 days Blastula http://www.youtube.com/watch?v=6lnr4HWiz9M • Identify the zygote. • Where is cleavage occurring? • 3. Identify the photo showing the blastula.
6. Identify the structure that the blastula attaches to. • Endometrium • (lining of uterus) Occurs 9 – 10 days after conception.
Endometriosis occurs when tissue normally found in a woman’s uterus grows outside of the uterus. • Each month, this displaced tissue goes through the normal menstrual process, thickening and then shedding through bleeding. However, since it has no way to exit the body, it becomes trapped and can irritate the areas around it, causing pain, scarring, infertility and other issues. • The cause of endometriosis is not known. Symptoms include: • Painful periods • Pelvic pain • Pain with urination or bowel movements (often during monthly periods) • Trouble getting pregnant
7. Identify the structure that the forms after the blastula. • Gastrula Describe the difference between structure of the blastula and gastrula.
8. Identify the three layers that make up the gastrula. • Endoderm • Mesoderm • Ectoderm
Look at the prefix of each word to help you identify each layer. • Endoderm • Mesoderm • Ectoderm A B C
1. Endoderm = inner layer 2. Mesoderm = middle layer 3. Ectoderm = outer layer A Mesoderm Ectoderm B C Endoderm
Gastrulation http://www.youtube.com/watch?v=Lgb4wMsZwZA&feature=related
Do any of the cells that make up these structures have a function? What are these cells called?
9. Identify and describe the process that occurs to the three germ layers that make up the gastrula. • Differentiation • Layers start to develop into different cells and eventually different structures
Identify what the cells of the ectoderm differentiate into. • Identify what the cells of the mesoderm differentiate into. • Identify what the cells of the endoderm differentiate into.
10. Identify the process represented by process 1. Fertilization 11. Identify the name of structure 2 how many chromosomes it contains (in humans). 46
12. Identify the process occurring in structure 3 and 4. Cleavage 13. Identify structure 5. Morula 14. Identify structure 6. Blastula
15. Identify structure 7 and the three layers that make up this structure. Gastrula Endoderm, mesoderm and ectoderm 16. Identify the process that occurs after structure 7 is formed. Differentiation
