Step Procedure accomplished Data collected 1 Mice are weighed Body weight 2 Mice are bled for hematology 3 Mice are euthanized - 4 Brain is dissected and weighed Brain weight 5 Heart is dissected and weighed Heart weight 6 Liver is dissected and weighed Liver weight 7 Rt. and Lt. Kidneys are dissected and weighed Kidney weights 8 Spleen is dissected and weighed Spleen weight
• Top loading balance: Ohaus Navigator, Model N12120 with internal calibration (Ohaus Corp., Pine Brook, NJ).
• Analytical balance: Mettler-Toledo, Model AL54 (Mettler-Toledo, Inc., Columbus, OH).
• Fume hood: used for self-protection from any potential inhalants (either from the mouse or fixatives).
- Lily tubs: 64-oz paper bucket (Sweetheart Cup Company, Owings Mills, MD)
- Dissecting board or tray lined with disposable paper towels
- Masking tape, pins, or locking forceps: depending on personal preference to stabilize the mouse and facilitate dissection
- Small animal dissecting instruments: curve and straight iris scissors, curve and straight, and rat-tooth and serrated forceps
- Physiological (0.9%) saline or PBS (phosphate buffered saline): for rinsing tissues and removal of blood or debris (hair etc.)
- Parafilm©: all-purpose laboratory film (Alcan Packaging, Neenah, WI)
- Dilute solution of disinfectant detergent for quickly cleaning of instruments in between organ specimen or mouse sample
- Sterilizing solution of 70% ethyl alcohol for animal preparation and cleaning
Acclimation to test conditions
Mice are obtained at 8 and 16 wks of age (DOB +/- 3 days) from production rooms and are acclimated to test conditions for at least half-hour.
a. Mice are weighed and bled for hematology (see above), then immediately euthanized using CO2 asphyxiation or cervical dislocation.
b. Immediately after euthanasia, mice are prepared for dissection and selected organs carefully isolated and removed for weighing.
c. A piece of parafilm is placed on a Mettler analytical balance to be tarred or zeroed before each dissected organ is weighed.
d. The weighed organ is either fixed in preservative solution for later histology, or submitted immediately for flow cytometry, as in the case of the spleen.
e. Dissecting instruments are cleaned thoroughly in between mice samples.
f. For additional tips on dissecting a mouse see The Virtual Mouse Necropsy.
Body weights and organ (brain, heart, liver, kidneys, and spleen) weights are recorded for ages 8 and 16 wks.