The equine infundibulum and fibrin tags
Key words: infundibulum, equine, ovary, fibrin, tag, submerged,
anatomy, mare
Image size: 1815 x 1199 px
The complex infundibulum of a mare seen here (at left) submerged in water. Submerging an organ in water, which has practically the same specific gravity as soft tissue, often reveals nuances of anatomy that are not evident when the organ is not supported in this manner. This image reveals the infinite number of folds and crevices that assist in catching the oocyte after it is discharged from the ovulation fossa. As shown at right, these are not visible if the ovary is viewed out of water.
The complex infundibulum of a mare seen here (at left) submerged in water. Submerging an organ in water, which has practically the same specific gravity as soft tissue, often reveals nuances of anatomy that are not evident when the organ is not supported in this manner. This image reveals the infinite number of folds and crevices that assist in catching the oocyte after it is discharged from the ovulation fossa. As shown at right, these are not visible if the ovary is viewed out of water.
The infundibulum is closely associated with the ovary but in
the absence of a bursa that completely envelopes the ovary, its efficiency in
capturing the oocyte is not well understood. Also, the infundibulum is not
highly active in a mechanical sense ("waving" to catch oocytes) because its wall
contains very little smooth muscle. Interestingly, the rest of the uterine tube becomes progressively more muscular as it approaches the uterus.
The tags of fibrous tissue seen on the ovary at left, are sometimes referred to as "adhesions" but have been present in most mares seen by the author. Indeed, this has also been reported elsewhere (Kenney. R.M. 1993 A review of the pathology of the equine oviduct. Equine Vet.J.25: 42–46). They do not appear to be associated with infertility. These fibrous tags probably arise from hemorrhage that occurs at the time of ovulation. As with the infundibulim, these fibrous tags only become noticeable in submerged samples.
True peri-ovarian adhesions are rare. However, a view of an ovary from an aged mare (see below) shows an example of adhesion that could have interfered with fertility.
Image size: 1000 x 969 px
These adhesions could have formed through the usually innocuous process discussed above. Alternatively, they may have formed from an inflammatory process that ascended from the uterus.
Interestingly, fibrous tags (clearly visible here) similar to those on the ovary were also present across most of the peritoneal surface of the uterus in this mare, suggesting perimetritis in the absence of general peritonitis. It is of course possible that blood from an ovulation spread widely over this surface forming fibrin, then fibrous tags.
The author has a made a point of evaluating the ovaries of mares at post mortem, submerged in water. The majority of mares show fibrous tags such as these. In some cases, such as that shown below, there is little doubt that these "physiological" tags may compromise the ability of the infundibulim to capture oocytes.
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Despite the frequent occurrence of fibrin tags on the surface of the ovary and its adnexa, extensive experience with equine slaughter plant specimens has convinced this author that peri-ovarian adhesions such as those seen in cows are quite rare in mares. In this case, adhesions were severe and probably due to inflammation. A finger has been placed under some adhesions between the ovary and the mesopsalpinx. It is not known if this pathology caused infertility in this mare but it is possible.
Image size: 750 x 879px
The relative lack of periovarian adhesions due to inflammation in mares may be due to the fact that the utero-ovarian junction is an effective one-way valve in horses. In postmortem specimens, a dye solution can easily be forced from the uterus into the uterine (fallopian) tube in cattle but this is very difficult to do in mares.
True peri-ovarian adhesions are rare. However, a view of an ovary from an aged mare (see below) shows an example of adhesion that could have interfered with fertility.
Image size: 1000 x 969 px
These adhesions could have formed through the usually innocuous process discussed above. Alternatively, they may have formed from an inflammatory process that ascended from the uterus.
Interestingly, fibrous tags (clearly visible here) similar to those on the ovary were also present across most of the peritoneal surface of the uterus in this mare, suggesting perimetritis in the absence of general peritonitis. It is of course possible that blood from an ovulation spread widely over this surface forming fibrin, then fibrous tags.
The author has a made a point of evaluating the ovaries of mares at post mortem, submerged in water. The majority of mares show fibrous tags such as these. In some cases, such as that shown below, there is little doubt that these "physiological" tags may compromise the ability of the infundibulim to capture oocytes.
Image size: 902 x 1044px
Despite the frequent occurrence of fibrin tags on the surface of the ovary and its adnexa, extensive experience with equine slaughter plant specimens has convinced this author that peri-ovarian adhesions such as those seen in cows are quite rare in mares. In this case, adhesions were severe and probably due to inflammation. A finger has been placed under some adhesions between the ovary and the mesopsalpinx. It is not known if this pathology caused infertility in this mare but it is possible.
Image size: 750 x 879px
The relative lack of periovarian adhesions due to inflammation in mares may be due to the fact that the utero-ovarian junction is an effective one-way valve in horses. In postmortem specimens, a dye solution can easily be forced from the uterus into the uterine (fallopian) tube in cattle but this is very difficult to do in mares.
