Mast cells in the ovarian bursa of the golden hamster

In the golden hamster, the number and maturity of mast cells were determined in serial sections of the ovarian bursa stained with either toluidine blue and acid fuchsin or alcian blue and safranin. The number of mast cells in connective tissue within 250 microns of the bursal mesothelium significantly decreased on Day 4 compared to the numbers between Days 1, 2, and 3 of the estrous cycle. The number of mast cells in connective tissue within 50 microns of the bursal mesothelium significantly decreased from Day 1 to 2 of the cycle, but did not vary between Days 2 and 4 of the cycle. Mast cells in this zone accounted for approximately 40-50% of the mast cells located within 250 microns of the bursal mesothelium throughout the cycle. If the tissue volume is taken into consideration, mast cells occurred in concentrations several times higher in connective tissue close to the bursal mesothelium than in connective tissue more distant from the mesothelium. Mast cells were occasionally located in the layer of bursal mesothelium, and some of them appeared to discharge granules into the bursal cavity. All mast cells encountered in the hamster bursa were mature cells, which stained reddish-orange with safranin. These results suggest that mast cells in the golden hamster ovarian bursa may act on the submesothelial connective tissue, bursal cavity, or ovary. The possible biological significance of their proximity to the bursal mesothelium is discussed.