diff --git a/appendix.tex b/appendix.tex
index 3853bc5..8086e4f 100644
--- a/appendix.tex
+++ b/appendix.tex
@@ -29,6 +29,19 @@ \chapter{Supplementary material for \texorpdfstring{\cref*{sec:trna}}{chapter 2}
     occupancy at \trna gene loci, differential expression analysis of \trna
     genes, and anticodon isoacceptor abundance analysis.}
 
+\textfig{mrna-heatmap}{spill}{\textwidth}
+    {Hierarchical clustering of \mrna gene expression correlations.}
+    {The heatmap shows the Spearman correlations of \mrna gene expression values,
+    representing the same data as \cref{fig:mrna-pca}. The samples cluster
+    hierarchically by tissue, followed by developmental stage.}
+
+\textfig{trna-heatmap}{spill}{\textwidth}
+    {Hierarchical clustering of \trna gene expression correlations.}
+    {The heatmap shows the Spearman correlations of \trna gene expression values,
+    representing the same data as \cref{fig:trna-pca}. The samples cluster
+    hierarchically by tissue, followed by developmental stage, with few
+    exceptions.}
+
 \textfig{correlation-plots-rnaseq-pol3}{text}{0.7\textwidth}
     {Correlation of \rnaseq and \pol3 \chipseq data during mouse liver and brain
     development.}
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diff --git a/gfx/supplements/trna-heatmap.pdf b/gfx/supplements/trna-heatmap.pdf
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