Morphologic comparisons among equine endometrium categories I, II, and III, using light and transmission electron microscopy.

This research study investigates the cellular changes in different categories of equine endometrium using light and transmission electron microscopy. The study finds that the most severe changes in cell structure, likely reducing fertility, are seen in category-III endometrium.

Objective

The prime objective of the study was to analyze whether the pathological changes visible under light microscopy in categories II and III endometrium are mirrored in the cellular changes. In addition, the study aimed to outline the differences in endometrial cell ultrastructure during estrus and diestrus cycles.

Methodology

• The research was conducted on 18 healthy mares.
• Biopsies of endometrial tissues during the physiological breeding season, were categorized using light microscopy and further studied under TEM (transmission electron microscopy).

Results

• During diestrus, glycogen granules were found to be associated with giant mitochondria in all types of endometrium, as seen through TEM.
• The development of rough endoplasmic reticulum (RER) and the Golgi apparatus signified protein synthesis in endometrial glands during diestrus.
• TEM didn’t show any significant ultrastructural disparities between categories I and II endometrium. This contrasted the differences identified by light microscopy.
• The most prominent pathological alterations were observed in category-III tissue, under both TEM and light microscopy.
• Category-III endometria displayed a large amount of light cells with more degenerative structures and fewer organelles. These also lacked cilia in the lumen of the glands, had extensive fibrotic tissue in the lamina propria (a thin layer of connective tissue) and numerous inflammatory cells in most tissue layers.

Conclusions

• The study concluded that severe ultrastructural changes might be one of the many factors responsible for the decline in the fertility of mares with category-III endometrium compared to those with category-I and category-II endometrium.