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Unformatted text preview: Graphs for lab reports if yours isn't done correctly, and you don't understand the format or how to do it in Excel, see me. Plagiarism: to steal and pass off (the ideas or words of another) as one's own : use (another's production) without crediting the source without crediting the source sharing of graphs is plagiarism DEVELOPMENTAL BIOLOGY 1 5 15 21 36 42 44 Staging a technique for quantifying developmental progress based on the appearance of key structures or features timebased scale: rate of development (progress/time) can vary due to environmental factors temperature, chemicals Landmark features/processes
Cleavage early cell divisions of zygote Blastula ball or disc of cells with hollow cavity (blastocoel) Gastrula internal tissue layers forming through movement of cells inward through blastopore or primitive streak Neurula formation of central nervous system
blastopore/yolk plug neural fold Primitive streak (chick embryo) groove along midline on dorsal side of blastodisc Somites repeated blocks of mesoderm
primitive streak somites LAB EXERCISES: Living frog embryos from have been reared at four different temperatures: 3.8o C 22.8o C 37.0o C 41o C Look at embryos from each temperature treatment determine stage of development using features such as cell number, blastopore, neural folds, etc. Predictions? What are these temperatures in degrees Fahrenheit? Prepared slides :
Chick whole mounts: 1. 18 hour 2. 24 hour 3. 48 hour 4. 72 hour 5. 96 hour Suggestion: look at chick embryos in chronological sequence: youngest to oldest. Look for (and include in your drawings) the appearance/development of the following: head fold, Hensen's node, primitive groove, neural fold, somites, notochord, eye, heart (=ventricle/atrium), limb buds 72hour chick 96hour chick Use the dissecting scopes or lowpower objective on compound scopes. You can break the slides with higher power objectives. Magnification Illumination control Objective lens Remember: Frog development and chick development vary significantly because of different amounts of yolk in the egg Mesolecithal (frog) vs. macrolecithal (chick) Also: chick embryos are cleared and stained; frog embryos are living material Drawings
Need not be photographically accurate, but schematic show relative locations and sizes of parts you can identify Drawings should always be labeled with: a) the subject (i.e., 48hour chick embryo) b) the magnification at which the subject was observed (i.e., 24x) c) prominent or identifiable parts indicated with arrows To do:
1) Frog embryos: look at embryos from each of the four temperature treatments determine stage using Table 1 (p. 13) and diagrams record stages in Table 1 (p. 15) draw one embryo from each treatment 2) Chick embryos: look at each of the five slides draw 3 embryos, labeling prominent features refer to Table 2 (p. 14) for stages To turn in March 20:
1) Labeled drawings of frog embryos (4) 2) Data in Table 1 (p. 15) 2) Labeled drawings of chick embryos (3) 3) Brief answers to questions 2, 3 and 4 on p. 14. Refer to the data in Table 1 in your answer to #2. ...
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- Spring '08
- Developmental Biology