Steps Procedure performed Age (wks) Equipment and reagents Data collected 1 Male mice aged and acclimated before survey 29-67 - - 2 Mice weighed and anesthetized 29-67 balance scale, needles and syringes, anesthesia body weight, body length 3 Mice euthanized 29-67 dissecting kit - 4 Both left and right retroperitoneal fat pads dissected 29-67 dissecting kit, balance scale perirenal fat pads weights 5 Both left and right testicular fat pads dissected 29-67 dissecting kit, balance scale gonadal fat pad weights 6 Both left and right kidneys dissected 29-67 dissecting kit, balance scale kidney weights 7 Heart dissected 29-67 dissecting kit, balance scale heart weight
• small animal dissecting kit
• analytical balance scale
• ruler or caliper
• dissecting board
• dissecting scope
• paper towels
• disinfectant solution
• rodent anesthesia: 70 mg/kg ketamine +10 mg/kg xylazine (5 mL/kg)
• needles and syringes
• 95 % ethanol
a. Male mice between the ages of 29-67 wks are initially measured for body weight (to the nearest 0.1 g) then anesthetized, before measuring body length (from the base of the lower incisors to the base of the anus, distance to the nearest 1 mm).
b. While still under deep anesthesia, the mice are euthanized by exanguination.
c. Following complete exanguination, the dissection of both the left and the right retroperitoneal fat pads, adipose tissue from the perirenal capsules as well as adipose tissues attached to the dorsal body wall near the kidneys are conducted, with the removal of adrenal glands embedded in the adipose kidney capsules.
d. No attempt is made to isolate and discard the renal artery and the ureter from the retroperitoneal fat pads.
e. Gonadal fat pads in male mice are dissected according to their defined proximity to the epididymis and vesicular gland (See lower panel in the figure below).
f. Gonadal fat pads in female mice are dissected accordingly with their defined location and direct proximity to the ovaries and uterus (See lower panel in the figure below).
Investigator's note: "Although the epididymal (male) and parametrial (female) fat depots are categorized with a single label (gonadal), these depots are different in structure and possibly differ in function."
g. Other adipose tissues associated with the omental membrane, ileum, jejunum, or duodenum (mesenteric fat pads) are not removed or measured.
h. Following the dissections of the four total fat depots, they are weighed individually to the nearest 0.01 g.
Data collected by investigator
Fat pads:gonadal fat pads weight and perirenal fat pads weight
Whole body metrics: body length and body weight
Organ weight: heart weight and kidneys weight
Definitions and calculations
Normalized weights = (raw weight ÷ body weight) × 100
BMI = body mass index [kg/m2] = (body weight in g x (kg/1000g)) ÷ ((body length in cm x (m/100cm)) x (body length in cm x (m/100cm))