Accumulation of chromotrope 2R positive cells in equine endometrium during early pregnancy and expression of transforming growth factor-beta 2 (TGF-beta 2).

This research studies the accumulation of specific cells in the uterine tissue of pregnant mares and the expression of a particular protein, the Transforming Growth Factor-beta 2 (TGF-beta 2), during early pregnancy. It notes that these cells start to appear from day 38 of gestation and are seen within certain areas of the uterine tissue at different stages of gestation.

Study of TGF-beta 2 in Uterine Tissue During Gestation

• The researchers collected endometrial or uterine tissue from the pregnant mares and looked for mRNA that would match with particular cDNA and RNA probes from a mouse TGF-beta 2 1.2 kb cDNA clone.
• The mouse cDNA probe matched with some characteristic TFG-beta2 mRNA transcripts in a type of test called a northern blot. These transcripts were identified in total RNA isolated from uterine tissue samples collected from the mares at day 45 of gestation.
• Major 4.0, 3.5 kb transcripts and possibly a minor 1.6 kb transcript were observed, suggesting specific match to equine TGF-beta 2 mRNA.

Observation of TGF-beta 2 During Different Stages of Gestation

• Using in situ hybridization, a biological process that localizes the RNA or DNA sequences within the tissue, the researchers found that clusters of cells matched with the riboprobes transcribed from the fragment used in the previous northern analysis. These clusters were found between endometrial glands on specific days of gestation (38, 40, 42, 43, 78, and 81).
• Notably, these matched clusters were not observed before day 38.
• From day 38 to day 43, significant hybridization happened over maternal leucocytes in the region of the developing endometrial cups. At subsequent stages (day 78 and 81), clusters of cells displaying TGF-beta 2 were found within the dense band of leucocytes at the periphery of the degenerating endometrial cups.

Characteristics of TGF-beta 2 Positive Cells

• The study also revealed that there was no hybridization to invasive or non-invasive trophoblasts, which refer to cells providing nutrients to the embryo, or to fully differentiated endometrial cup cells.
• An estimated 90% of TGF-beta 2 positive cells identified in day 78 sections also stained with chromotrope 2R, used to detect a type of white blood cell called eosinophils.
• Additionally, about 50% of these stained cells had a morphology that was characteristic of eosinophils.