Dissection

How To - For absolute beginners

For the individual steps, techniques might vary and you might want to try different approaches if you are still learning.

Not everything written here, might be the best way for you or even in general.

Before performing any experiment make sure you are allowed to do so.

1. Put on gloves and wear a red headlight
2. Kill mouse, but
   • Only if you have a Sachkundigennachweis and are on the Tötungsmitteilung
   • Otherwise ask someone who is allowed to kill it for you
3. Put mouse in box
   • From now on you should be quick. The retina does not have oxygen supply.
4. Bring mouse into dark room
5. Pick one eye and mark dorsal side of one eye
   • Test marker first on paper
   • Mark dorsal side
   • Test marker after eye again on paper
   • If a test fails, better take another marker and start again
6. Cut out eye
   • If it was the left eye, put it left and vice versa.
7. Repeat 5 and 6 for the other eye
8. Open eyeball
   • Gently hold the eye with a forceps, take the second one for support if necessary
   • Take a 19x0.4 needle in the free hand and pinch a whole in the cornea
   • Make a small cut into the cornea to let oxygen in
   • Put eye back to its position (left or right) again
9. Repeat 8 for the other eye
10. Continue with this eye and make dorsal cut
    1. Make sure to cut sufficiently deep into the retina to be able to distinguish the cut from potential tear
11. Remove cornea with forceps and scissor
    1. Hold cornea with forceps (non-dominant hand)
    2. Cut with dominant hand
    3. Cut close to where you hold the cornea
    4. Sometimes you may want to use two forceps to readjust the positioning
12. Remove lens
    1. Grab it with dominant hand
    2. Hold eye cup with other hand
    3. Pull out lens, you may need to grab the eye cup at different locations
13. Remove eye cup
    1. Peal it off
    2. don’t pull violently. If the retina is stretched too much, it will be damaged
    3. Instead try different positions
14. Remove vitreous
    1. Grab vitreous with dominant hand
    2. Block retina on edge (don’t grap it) with other hand
    3. Make quick vertical movement (just slightly upwards too) with dominant hand to pull the vitreous out
    4. Repeat this over on over again until the retina is free of vitreous
15. Repeat 10-14 for the other eye