Quantification of mucosal eosinophils and mast
cells in the oviducts from 22 crossbred heifers was
performed in both natural (estrus, metaestrus and
diestrus) and superovulated (estrus and metaestrus)
estrous cycles. The number of cells/square millimeter of
mucosa was obtained through counts at different regions
of the oviduct (infundibulum, ampulla,
ampullary/isthmic transition and isthmus). Differences
were not found (P > 0.05) among numbers of cells at the
different phases of the natural estrous cycle nor between
natural or superovulated cycles. When all animals were
separated into two phases of the estrous cycle (estrus
and metaestrus), the number of eosinophils at the
ampullary/isthmic transition and isthmus was higher
(P < 0.01) at the estrus cycle phase, and the number at
the infundibulum was higher (P < 0.001) during the
metaestrus phase than at estrus. The number of mast
cells was highest at the isthmus regardless of the estrus
phase, and highest at the infundibulum (P < 0.001) and
ampulla (P < 0.05) during the metaestrus phase.
Significant correlations were found between the
number of mast cells and plasma progesterone levels
at the infundibulum (P < 0.001; r = 0.69) and ampulla
(P < 0.03; r = 0.51). No correlation was seen between
numbers of eosinophils and mast cells, progesterone and
17β-estradiol concentrations. Therefore, the distribution
of mucosal eosinophils in the oviduct of heifers is
apparently not related to the circulating levels of 17β-
estradiol and progesterone; however, the highest
number of mast cells found at the metaestrus phase of
the cycle, at least for the infundibulum and ampulla,
appears to be related to the high circulating
progesterone plasma levels in metaestrus phase
compared to estrus phase. No differences were found
between animals subjected or not to superovulation.
