Living fibroblast cells in the oviductal masses of mares

The object of this experiment was to estimate the number and type of living cells in oviductal masses of mares. Oviducts of abattoir mares were dissected, divided into 3 sections, and flushed individually. Oviductal masses were recovered from 220 of 250 mares and from 389 of 500 oviducts. A greater number of masses was recovered from the left than the right oviducts. A higher percentage of masses was recovered from the ampullary-isthmic junction than from the ampulla or isthmus. The number of masses increased slightly with increasing mare age and was weakly correlated with the number of unfertilised oocytes recovered per oviduct. Prepubertal mares had fewer recovered masses than anovulatory, early luteal phase, late luteal phase, or pregnant mares. Oviductal masses were classified morphologically as being branched, compact, or cumulus. Living cells were identified with a carboxy fluorescein diacetate stain and dead cells were identified with a propidium iodide fluorescent stain. In branched masses, the proportion of the surface area covered with total cells (live and dead) was 33.7 +/- 14.3%, and with only live cells was 6.2 +/- 7.3%. In compact masses, the proportion of the surface area covered with total cells was 42.4 +/- 21.2%, and with only live cells was 10.7 +/- 13.1%. The detection of living cells was confirmed by isolating and culturing cells. Cells cultured from cumulus masses were viable in 57.1% of wells, whereas cells from branched and compact masses were viable in only 18.1% and 17.7% of wells, respectively. In addition, more of the surface area of wells containing cells from cumulus masses were covered with cells, compared to wells containing cells from either branched or compact masses. Most cells appeared to be fibroblasts because 90-95% of cells from branched and compact masses were stained with a fibroblast cell marker.