Any process that decreases the frequency, rate or extent of mesenchymal cell proliferation that contributes to the progression of the ureter gland over time. A mesenchymal cell is a cell that normally gives rise to other cells that are organized as three-dimensional masses, rather than sheets.
Synonyms:
related_synonym:
negative regulation of ureter mesenchymal cell proliferation; negative regulation of ureteral mesenchymal cell proliferation