5709a7858d5c197721be66d5218a79124abadb70
lrnassar
  Tue Mar 17 08:46:31 2026 -0700
Adding alt text to images across static documentation pages, CGI headers, markdown docs, and Pandoc templates. Content images receive AI-generated descriptive alt text; decorative images (icons, spacers, toggles) receive alt="" per WCAG best practice. Also adds Image Descriptions section to the accessibility page, and fixes Pandoc Lua writers to output alt attributes. 67 files, covering help docs, news archive, ENCODE pages, portal pages, and session examples. refs #37254

diff --git src/hg/htdocs/singlecell.html src/hg/htdocs/singlecell.html
index 7b781d1f4b5..fa9b69194bb 100755
--- src/hg/htdocs/singlecell.html
+++ src/hg/htdocs/singlecell.html
@@ -78,49 +78,49 @@
           <li>View heatmap showing selected gene expression across clusters</li>
           <li>Rename clusters and add custom annotations to a selected set of cells</li>
         </ul>
         Contact us at
         <a href="mailto:&#99;&#101;&#108;&#108;s&#64;&#117;&#99;s&#99;.
         &#101;&#100;&#117;">
         &#99;&#101;&#108;&#108;s&#64;&#117;&#99;s&#99;.&#101;&#100;&#117;</a>
         <!-- above address is cells at ucsc.edu -->
         to request new datasets or suggest improvements.
         To set up your own cell browser, follow our <a href="https://cellbrowser.readthedocs.io/"
         target="_blank">installation and set up instructions</a>.
         </p>
 
         <p class="text-center">
         <a target=_blank href="https://cells.ucsc.edu" alt="Screenshot of UCSC Cell Browser">
-            <img style="width:100%" src="<!--#echo var="ROOT" -->/images/cellbrowser.png">
+            <img style="width:100%" alt="UCSC Cell Browser showing a t-SNE plot of single-cell clusters colored by cell type" src="<!--#echo var="ROOT" -->/images/cellbrowser.png">
         </a>
         </p>
     </div>
     <div class="col-md-6">
         <h2>Single cell datasets in the UCSC Genome Browser</h2>
         <p>
         Below is a screenshot of a
         <a target="_blank"
         href="http://genome.ucsc.edu/s/Max/tabMuris">public session</a>
         that highlights the Tabula Muris gene expression track.
         The session shows the Sox10 locus. The gene expression track at the top shows that the
         gene is only well expressed in basal cells (orange), mammary gland (blue) and oligodendrocytes (pink).
         These cell type names are shown when you hover with the mouse over the bars on
         the genome browser. The coverage tracks below show that all exons are
         transcribed in these, but the last exon is also transcribed in stromal cells
         and some non-coding transcription is seen in goblet cells 3' of the gene. The
         splicing tracks below show that proper splicing is limited to the four cell types
         described above. This is also a non-coding region conserved in zebrafish and chicken.
         </p>
 
         <p class="text-center">
         <a target="_blank" href="http://genome.ucsc.edu/s/Max/tabMuris" alt="genome browser session link">
-                <img src="../images/screenshot-tabMuris.png" style='width:100%'>
+                <img alt="Genome Browser session showing Tabula Muris single-cell RNA-seq expression at the Sox10 locus" src="../images/screenshot-tabMuris.png" style='width:100%'>
         </a>
         </p>
     </div>
 </div>
 
 <!--#include virtual="$ROOT/inc/gbPageEnd.html"-->
 
 <script type='text/javascript' src='/js/hgGtexTrackSettings.js'></script>