At the time of necropsy, 52 tissues for females and 53 tissues for males are examined by trained technicians for gross abnormalities. Collection and photography of tissues occurs only if there are significant gross lesions. Collected tissues are immersion-fixed in 10% neutral buffered formalin for 24 hours, trimmed, processed to paraffin, embedded, sectioned at 4-5 mm, and stained with hematoxylin and eosin for histopathological examination. A board-certified veterinary pathologist examines tissues from one male and one female homozygote for each knockout line (heterozygotes are examined for homozygous lethal projects). When possible gene-related lesions are identified, complete gross and histopathologic examination is completed on four additional homozygous mice (2 males and 2 females).

NOTE: We only include images of histopathological examination in each data set upon abnormal findings.