Morpho-functional studies regarding the fertility prognosis of mares suffering from equine endometrosis.
Abstract: The aim of the present study was to characterize the morpho-functional features of endometrosis in barren and foaling mares, using both conventional histopathological and immunohistochemical methods. Endometrial biopsy samples were collected during the physiological breeding season from 159 estrous, clinically healthy mares (mean age 12 years), and the quality and degree of endometrosis was histomorphologically defined. The mares were bred and those that foaled were put in the foaling group whereas those that did not foal were placed in the barren group. Foaling mares were then compared with barren mares. Sixty-four percent (101/159) of uterine samples showed varying degrees of endometrosis and were used for this study. The sample population consisted of 51 barren and 50 foaling mares suffering from endometrosis. Expression of steroid hormone receptors (estrogen receptor, progesterone receptor) and endometrial protein secretion patterns (uteroglobin [UG], uterocalin [UC], calbindin(D9k) [CAL], uteroferrin [UF]) was evaluated by immunohistochemistry (barren mares N = 51, foaling mares N = 31). In comparison with unaffected glands, fibrotic glands generally showed a cycle-asynchronous, partially patchy protein expression pattern which is interpreted as a sign of endometrial maldifferentiation within fibrotic areas. In barren mares (N = 51) more than half of biopsy samples (27/51) showed a destructive mostly moderate (20/27) type of endometrosis. In affected glands, staining for UG (17/21) was decreased (P < 0.001). Foaling mares (N = 50) frequently showed a mild, nondestructive endometrosis (35/50). Compared with barren mares, foaling mares had statistically (P < 0.05) more often a cycle-synchronous or increased UG expression pattern within fibrotic glands. Obvious deviations of either UG or UC rarely occurred. Within fibrotic foci, UF often demonstrated a cycle-synchronous or more intense expression pattern in both foaling (28/31) and barren mares (41/51), compared with healthy glands. Mares of both groups showed a cycle-asynchronous staining for estrogen receptor and progesterone receptor in the stromal cells in areas of periglandular fibrosis and the glandular epithelia. These findings indicate that affected areas become independent of the uterine control mechanisms and exhibit specific differentiation dynamics. Immunohistochemical investigations showed that the secretory patterns differ between barren and foaling mares. The findings in this study should be considered as a useful addition to the "classical" Kenney categorization.
Copyright © 2011 Elsevier Inc. All rights reserved.
Publication Date: 2011-08-23 PubMed ID: 21855986DOI: 10.1016/j.theriogenology.2011.06.001Google Scholar: Lookup
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Summary
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The study investigates the characteristics and implications of endometrosis—a common uterine condition—in mares (female horses), particularly concerning their ability to conceive and give birth to offspring. The researchers utilized histopathological and immunohistochemical techniques on collected endometrial biopsy samples from 159 mares, and analyzed the correlation between the level and type of endometrosis with the mares’ fertility outcome.
Study Method and Population Breakdown
- The study comprised of first collecting endometrial biopsy samples from 159 estrous (in heat, and therefore ready to conceive), clinically healthy mares within the normal breeding seasons.
- The mares, which had an average age of 12 years, were categorized based on their ability to foal (give birth) after being bred. Those that gave birth were put in the ‘foaling mares’ group while those who didn’t were classified as ‘barren mares’.
- The researchers detected endometrosis of varying degrees in 101 of these samples, which were subsequently used for further analysis.
- The final population for this study involved 51 barren and 50 foaling mares with endometrosis.
Fertility Markers and Their Expression
- The study also assessed the expression of steroid hormone receptors (specifically estrogen and progesterone receptors) and different endometrial protein secretion patterns, including uteroglobin (UG), uterocalin (UC), calbindin(D9k) (CAL), and uteroferrin (UF) among others. These markers were analyzed by conducting immunohistochemistry on biopsy samples from both barren mares and foaling mares.
- Fibrotic (scarred or damaged) glands generally showed inconsistent protein expression patterns, possibly indicating endometrial malformation within fibrotic areas. The barren mares’ biopsy samples more than often exhibited a moderate type of destructive endometrosis. The researchers noticed decreased staining for UG in affected glands.
- Conversely, the foaling mares majorly displayed a milder, nondestructive type of endometrosis. Compared to barren mares, these foaling mares had statistically more frequent or higher UG expression levels within fibrotic glands. Other significant deviations regarding UG or UC were seldom found.
Findings and Relevance to Fertility
- Both barren and foaling mares exhibited inconsistent staining for estrogen and progesterone receptors in their stromal (connective tissue) cells and glandular epithelia (layers of cells forming the gland’s interior). This shows an independence of the affected areas from uterine control mechanisms, hinting at specific differentiation dynamics within.
- The immunohistochemistry results demonstrated that secretory patterns varied between barren and foaling mares, hinting this may be a significant factor when investigating or predicting a mare’s fertility state in relation to endometrosis.
- In conclusion, these findings should be considered as a valuable addition to the traditional Kenney categorization for assessing equine fertility.
Cite This Article
APA
Lehmann J, Ellenberger C, Hoffmann C, Bazer FW, Klug J, Allen WR, Sieme H, Schoon HA.
(2011).
Morpho-functional studies regarding the fertility prognosis of mares suffering from equine endometrosis.
Theriogenology, 76(7), 1326-1336.
https://doi.org/10.1016/j.theriogenology.2011.06.001 Publication
Researcher Affiliations
- University of Leipzig, Faculty of Veterinary Medicine, Institute of Pathology, Leipzig, Germany. equinevet@gmx.de
MeSH Terms
- Animals
- Calbindins
- Endometriosis / pathology
- Endometriosis / veterinary
- Endometrium / metabolism
- Endometrium / pathology
- Female
- Horse Diseases / pathology
- Horses
- Immunohistochemistry
- Infertility, Female / complications
- Infertility, Female / epidemiology
- Infertility, Female / veterinary
- Receptors, Estrogen / metabolism
- Receptors, Progesterone / metabolism
- S100 Calcium Binding Protein G / metabolism
- Uteroglobin / metabolism
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