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To identify (by naked eye or with a dissecting microscope) malformations or pathomorphological lesions that characterize the mouse. Tissues collected for subsequent examination require appropriate handling and preservation to prevent tissue deterioration. The service includes: 

  • Macroscopic inspection of organs 
  • Organ weights (liver, kidney, spleen, heart, visceral fat) and total body weight and length


  • Stereomicroscopes 
  • Automated macroscope equipped with digital camera 
  • Necropsy bench


Number of mice: six experimental mice (three males and three females) and six age-matched controls (three males and three females) are a minimum required. 
Age: Analyses are performed at about 4 months of age. However, as mutations/treatments may affect the propensity to develop age-related diseases, it may be necessary to investigate old (i.e. over 12 months of age) and eventually senescent (i.e. over 24 months of age) subjects to discover pathological phenotypes.

All listed organs are dissected following a systematic necropsy procedure or, alternatively, collected according to gene expression patterns or to clinical findings. If the effect of the mutation is unknown, a systematic necropsy is recommended for each mouse.

Functional systemTissues
Cardiovascular systemHeart; aorta
Respiratory systemTrachea, lungs
Digestive organs Liver, pancreas (exocrine), salivary glands
Digestive tract Esophagus, stomach, duodenum, ileum, colon
Central nervous system Brain
Sensory organsEye and adnexia, tongue
Endocrine system Pituitary, thyroid, and adrenal glands, pancreas (endocrine)
Immune and haematopoietic systemThymus, spleen, lymph nodes, bone marrow
Urinary systemUrinary bladder, kidney
Male reproductive systemTestis, epididymis, prostate, seminal vesicles, preputial glands
Female reproductive system Ovaries, oviducts, uterus, vagina
Musculoskeletal systemStriated muscle, knee joint
Supporting and connective tissuesWhite and brown adipose tissue
Integumentary system and mammary gland Skin and appendages, mammary gland

Histopathological evaluation of organs


Standard histopathological evaluation is performed on 10 % formalin fixed paraffin embedded 5µm-thick and hematoxylin & eosin stained sections (see histological techniques). All lesions are scored to enrich analyses with basic statistics. This allows to propose more comprehensive reports.

Special histopathological evaluation can also be performed: Detection of atherosclerotic lesions using en face staining of aorta. Whole aortas are dissected under stereomicroscopes and stained with Sudan IV, the lesions are subsequently quantified.


Automated research microscope equipped with a digital camera.

Slide scanner Nanozoomer 2.0 HT (Hamamatsu Photonics K.K., Hamamatsu City, Japan).


Different fixation methods can be used according the needs (see histological techniques)

Strategy of systematic analysis


To allow "meaningful" scientific interpretation of histopathological data through analysis of large cohorts of mice. On a practical level, 24 mice per age group (i.e., number used in systematic clinical tests) is recommended. However, as it takes several hours of technician time to collect, process and stain the tissues of a single mouse, economical aspects must be taken into account. These time considerations highlight the need for a phenotyping strategy.

  • Step 1. Each age group is subdivided into two subgroups. Mice from subgroup A are subjected to systematic macroscopic and microscopic analyses. Mice from subgroup B are subjected to systematic necropsy and to a targeted histological evaluation. 
  • Step 2. A preliminary histopathological report is made available in 5 weeks after necropsy. 
  • Step 3. Depending on the histological findings, a second round of targeted histological analysis of subgroup B mice may be undertaken with the objective of increasing the statistical significance of the observations.


  • Comparative pathology reports and expertise 
  • Sets of stained slides 
  • Macroscopic and microscopic images of the lesions in e-format (upon request)
  • Fixed tissues
  • Tissues frozen in liquid nitrogen for RNA analysis (upon request)
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