<p>The first use of this strain designation was UM-HET3</p>
<blockquote>
<p>Miller, R. A., C. Chrisp, and A. Galecki. 1997. CD4 memory T cell levels predict lifespan in genetically heterogeneous mice. FASEB Journal 11:775-783</p>
</blockquote>
<p>UM-HET3 mice are neither an F1 nor an F2 hybrid. (An F2 hybrid is made by crossing males and females of the same F1 hybrid stock.) The correct designation is a "four-way cross."</p>
<p><a href="https://www.nia.nih.gov/research/dab/interventions-testing-program-itp/publications-nia-interventions-testing-program" target="_blank">Publications from the NIA Interventions Testing Program</a></p>
<p>The first ITP paper also referred to these mice as UM-HET3, using this strain designation regardless of the site at which the mice were produced. <br aria-hidden="true" />
See: </p>
<blockquote>
<p>Miller, R. A., D. E. Harrison, C. M. Astle, R. A. Floyd, K. Flurkey, K. L. Hensley, M. A. Javors, C. Leeuwenburgh, J. F. Nelson, E. Ongini, N. L. Nadon, H. R. Warner, R. Strong. 2007. An aging interventions testing program: study design and interim report. Aging Cell 6: 565 - 575. [PMC: 17578509]</p>
</blockquote>
<p><a href="https://phenome.jax.org/projects/ITP1" target="_blank">ITP1: Interventions Testing Program: Effects of various treatments on lifespan and related phenotypes in genetically heterogeneous mice (UM-HET3) (2004-2022)</a></p>
