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Ultrastructure of the secretory endometrium during oestrus in young maiden and foaled mares
Author(s) -
TUNÓN AM.,
RODRIGUEZMARTINEZ H.,
HAGLUND A.,
ALBIHN A.,
MAGNUSSON U.,
EINARSSON S.
Publication year - 1995
Publication title -
equine veterinary journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.82
H-Index - 87
eISSN - 2042-3306
pISSN - 0425-1644
DOI - 10.1111/j.2042-3306.1995.tb04074.x
Subject(s) - apocrine , endometrium , estrous cycle , epithelium , secretion , biology , endometritis , ultrastructure , endocrinology , medicine , pathology , anatomy , pregnancy , genetics
Summary Cyclical accumulation of uterine fluid occurs during oestrus and is often seen in excessive volumes in mares considered susceptible to endometritis. Since the mechanisms behind the formation of free uterine fluid remain to be clarified, the fine structure of the secretory equine endometrium was studied in biopsies collected during videoendoscopy from 14 endometritis‐free, 4–9‐year‐old mares during oestrus. A distinct oedema of the tunica mucosa was evident. The surface epithelium had both ciliated and nonciliated cells and, particularly at the uterine body, often presented intra‐epithelial macrophages. The epithelial cells of the gland duct were similar to the surface epithelium, except that the nonciliated cells lacked secretory vesicles. The mid‐deep glandular segment was, however, loaded with apical secretory vesicles in the nonciliated cells. This glandular epithelium presented clear signs of secretory activity with conspicuous secretory vesicles holding electron‐dense granula in the adluminal cytoplasm and a well developed supranuclear Golgi apparatus. Secretory products as well as cell debris were commonly found in the lumen of the glands. No clear signs of apocrine secretion were found and it seemed therefore, that the mechanism of secretion is merocrine, i.e. by exocytosis. The endometrial oedema and intense secretory activity, both under oestrogenic influence, contribute to the building up of the uterine fluid during oestrus. No differences in morphology of the secretory endometrium could be noticed between nulliparous mares and mares that had had 1 or 2 foals.