Pathology

Introduction

The pathology is an important screen in the GMC with more than 20 years of experience in rodent pathology unique in Germany.  Our team performs a systematic histopathological characterisation of genetically modified mouse lines in order to improve the understanding of mammalian gene function and its role in the development of human diseases, contributing to ways of preventing and treating them.

Integrated in the standard primary phenotyping pipeline of the German Mouse Clinic, the pathological screen plays a vital role in providing a diagnostic context for the in vivo phenotyping results and recognising further phenotypes not detected in high-throughput mouse screening pipelines (https://www.mousephenotype.org/impress/).

Primary Screen

During the necropsy, mutant and control mice are health monitored and fully morphologically characterised. The exact body and organ weight/length measurements and description of lesions in the organs are recorded and photographed by our experienced necropsy technical personnel.  The macroscopically terminology used is in agreement with the mouse phenotyping annotation of data for high-throughput phenotyping (https://www.mousephenotype.org/impress/procedures/14).

The organs are collected, fixed in 4 % neutral buffered formalin and embedded in paraffin. For histological examination, haematoxylin-eosin stain (HE) is routinely used in the 28 organs listed below.  Other organs such as brown and white fat, pituitary gland, nasopharynx, skeletal muscle, sciatic nerve and bone can also be histologically examined on as a special request.

SkinSpleenTestes
BrainLiverEpididymis
Cervical lymph nodeAdrenalsFuniculus spermaticus
Salivary glandsKidneyProstate
TracheaUrinary bladderMale accessory glands
ThyroidOesophagusOvaries
ParathyroidStomachUterus
HeartSmall intestineVagina
LungLarge intestine
ThymusPancreas

The microscopic analysis is performed by experienced veterinary or medical pathologists in identifying the incidence and severity of morphological manifestations of disease, taking into account sex, age and strain background derived-lesions and sectioning/staining artefacts. The use of digital documentation of histopathological findings (scanner Hamamatsu Photonics Deutschland GmbH) and standardised terminology allow images of tissues to be copied and its pathological diagnosis to be shared into a wider phenotyping community.

Secondary screening

Assuming  findings in the primary screen, additional specific targeted evaluations such special histochemical stains (Masson’s trichrome, Weigert’s elastic stain, Turnbull’s blue, Perls’ Prussian blue, Luxol Fast Blue, Tartrate resistant acid phosphatase (TRAP)  and  Periodic acid–Schiff),  immunohistochemistry and double immunohistochemistry can be performed in a secondary screen to provide further insight into the histopathological findings such as localisation of specific cells, tissue components and cell processes on histological sections.

For the immunohistochemistry technique more than 200 primary antibodies, originally designed against human proteins, have been tested and established for mouse tissue. It is performed in an automated slide staining system (Discovery Ventana Medical System, Roche) to address expression patterns of proteins for the following areas: hematology, cell and tissue markers, stem cell marker, cell cycle and processes, signal transduction, growth factors, endocrine markers and phospho-specific antibodies.

The photomicrographs below illustrate some of our histopathological findings.


A: Macroscopic appearance of the liver from a Jak1S645P+/− mouse reveals a congestive liver with irregular margins and prominent vessels. H&E stainings of the liver show a dilation of the hepatic sinusoidal plexus. Anti-CD31 IHC for endothelial cells illustrates an increased vascularization in the mutant liver. Scale bars: 200 μm; 500 μm. B: Reticulin silver staining (Gomori’s trichrome staining) visualizes an increase in hyperplastic hepatocytes neighbored by atrophic hepatocytes in a Jak1S645P+/− mouse. Masson’s trichrome staining excludes the presence of fibrosis in Jak1S645P+/− mice. Anti–p-Stat3 IHC depicts phosphorylation and nuclear localization of Stat3 in the hepatocytes of Jak1S645P+/− mice compared with Jak1wt mice demonstrating activation of the JAK/STAT pathway. Scale bar = 200 μm.

Sabrautzki et al., 2013, An ENU Mutagenesis-Derived Mouse Model with a Dominant Jak1 Mutation Resembling Phenotypes of Systemic Autoimmune Disease, The American Journal of Pathology, Vol. 183, No. 2, August 2013. doi:10.1016/j.ajpath.2013.04.027

Head

Dr. Julia Calzada-Wack MD     
phone: +49 (089) 3187-3241
fax:     +49 (089) 3187-3360
e-mail:

Scientist:

Dr. Patricia da Silva-Buttkus
phone: +49 (089) 3187-3241
fax:     +49 (089) 3187-3500
e-mail: dasilva-buttkusnoSp@m@helmholtz-muenchen.de

Staff

Anja Mantik

Jacqueline Müller

Marion Fisch

phone: +49 (089) 3187-2629 / 4579
fax: +49 (089) 3187-3360