Embryology

flat =Viewing Medaka= 1. Using a medicine dropper, place the egg in the depression on your slide with several drops of embryo rearing solution. Rotate the egg gently with a toothpick to view different areas of the egg. 2. Examine your egg under low magnification with a compound microscope. Label any identifiable structures including the **chorionic filaments**, **egg** **membrane**, and **oil droplets**. Consult a guidebook to help you identify these structures. Depending upon the approximate age of your egg (time after fertilization) you may be able to see several cells in early cell division or cleavage (2,4,8, 16 cell stage) or a blastula (mass of cells) at the pole opposite where most of the oil droplets are congregated (vegetal pole). Label the **dividing cells (blastomeres)** or **blastula** if visible. 3. Remove the egg from the depression slide and place it back in the container. 4. You will also need to change your water daily. You will do this by using a dropper to remove a little over half the water and then replacing it with new spring water.

=Pictures and information to collect:= 1. Take a picture and label any visible structures of your egg. Eventually, you should be able to see **__a streak or embryonic shield__** lying on the surface of the yolk. This is the beginning of the body of your embryonic fish. . Ectodermal cells from this area will form the nervous system of your embryo (brain, spinal cord). **__Optic buds__** may also be visible projecting from the primitive brain. These form an **optic cup** from which the parts of the eye develop. As development progresses during the second day, the embryo lies over the surface of and curves around the yolk. Various numbers of **__somites__** may also be visible in the tail or caudal region of your embryo. Somites form blocks of muscle tissue and bone tissue. A **primitive heart** may be visible below the head region by the end of the second day of development. By the end of the second day of development the three main regions of the brain should be visible.

2. Consult your guidebook or other sources available help you identify visible structures.

3. On each subsequent day, carefully observe, take pictures, label, and identify observable structures. Rotate and examine your egg at different angles and from different views to try and observe all structures. A possible sequence of events follows although the times at which structures appear vary with a number of environmental conditions.

4. When the **heart** is be clearly visible and beating, count and record the number of heartbeats during each day that you observe your embryo. As more **somites** are formed, count and record their number. Blood vessels should be visible over the yolk sack. Make sure you include these on your drawings. Carefully observe the eyes. Take pictures of new structures that you can observe as they form such as the **lens** or **cornea**. **Pigmentation** of the eye will also increase. The embryo is actively growing. The gut or digestive tube should be visible below the somites. Otoliths forming internal ear structures are present behind the area of the brain. **Fins** will begin to appear at the end of this period.

5. Organogenesis or formation of major organs and systems will occur. Continue to make sure to observe the heart and count the heart rate each day. Blood becomes red in color. There is increased blood flow and branching of vessels over the yolk. More fins develop. The embryo begins moving. Record the exact day when you first observe movement of the embryo. A green organ will become visible. This is the **urinary bladder**. A bright red organ is the **spleen**. The digestive tract should appear visible in the middle of the body of the embryo. The **liver** lies over the green colored urinary bladder. Your embryo should look more like a fish with each additional day of development. By day fourteen, the embryo should be ready for hatching. Time of hatching may vary and be as long as three weeks, however. Slowly swirl the fluid in the dish or container your egg is in to stimulate hatching. Record the day on which your embryo hatches. Carefully remove the small fish (fry) with a large plastic pipette into a depression slide with ample rearing solution. You will quickly make and record any other appropriate observations.

6. Keep careful records of the heart rate and numbers of somites and any other information that you can record. Major stages of development (heart beat, seeing pink blood, twitching...) are all notable and determine the stages of the embryo.

=Infographic - Your Medaka story=
 * You need to create two Infographic slides per group - each person is responsible for one. Between the two slides you must meet all of the requirements (labels, functions, did you know facts, etc.)

You are to create an Infographic of the life of your Medaka/Casper egg. You can tell about the development from the Medaka's point of view, create an anticipation for the great day of hatching, use some interesting narration to create interest, development of Medaka and other chordates, or other creative ideas. In your story, you must:
 * show pictures of the various stages (enough pictures to show all parts that were required).
 * discuss structures and the functions throughout (a good idea would be to include a did you know about structures that are similar with other vertebrates - other fish or animals - like us!) Here are some questions to answer: Why do the Medaka have filaments along the outside of the egg but the Casper do not? What other structures seem to be different or the same in the fish?
 * discuss developmental stages you saw (first heartbeat, etc.)
 * basics of what Medaka's require to survive to hatching **and** beyond hatching
 * be creative in your presentation. some examples: "how not to kill a fish", "what my fish must be thinking", "As new parents, we can't wait!", "The life and times of _", "What to expect when you are waiting for your fish to hatch," and more....
 * use any multimedia tool that can embed in the wiki. For example, you can write and create a newsletter but pages would show as a download, therefore you would need to upload to scribd or slideshare in order for it to show when your wiki page is opened. Some great applications you can use: comic life, cartoon online apps like pixton, glogster, voicethread, garageband, imovie, powerpoint/keynote, pages...
 * Did you know information such as how long it takes a fish to hatch, comparison of different kinds of fish, other organisms that have the same kind of structures when they develop, etc.

=Required Labels= • filament • chorion • cytoplasm • yolk sac • oil globule • heart • fin(pectoral, caudal, dorsal) • optic cup/eye • brain • mouth/jaws • somites

=Bonus Labels= • vitelline membrane • blood vessel • urinary bladder • swim bladder • spleen • liver • intestine

=Resources to learn about Medaka=

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= = =Embryology study guide=
 * 1) Embryonic stages in medaka:http://ani.embl.de:8080/mepd/medakaStages/MedakaDevStages.html
 * 2) Videos and pics of developing medaka: https://www.msu.edu/~timkophi/LBS144/medaka.htm
 * 3) Books are found along the back of the room. Please keep them in the room for all to have access.
 * 4) Information: http://www.fishbase.org/Summary/SpeciesSummary.php?id=4669
 * 5) Medakafish developmental stage map: http://www.bio.nagoya-u.ac.jp:8000/stage-map.html