Histology and mRNA arrays are two different services that may be offered by contract research organizations (CROs) to support preclinical research and drug development.

Histology services involve the examination of tissue samples using microscopy to study the structure and function of cells and tissues. This can include evaluating the effects of drugs on tissues and organs, identifying biomarkers of disease or drug response, and assessing the safety and efficacy of drug candidates. Histology services may include sample preparation, staining, and imaging, as well as image analysis and interpretation.

mRNA arrays, on the other hand, involve the analysis of gene expression patterns in tissue samples using microarray technology. This can provide valuable information on the molecular mechanisms underlying disease and drug response, as well as potential biomarkers of disease or drug efficacy. mRNA arrays may be used to identify genes that are upregulated or downregulated in response to a drug, or to study the effects of drugs on specific cellular pathways.

CROs may offer both histology and mRNA array services, as well as other related services such as immunohistochemistry, in situ hybridization, and gene expression analysis. These services can provide valuable insights into the safety, efficacy, and pharmacology of drug candidates in preclinical models, helping to guide drug development and inform clinical trial design.