Caspase-3-mediated apoptosis and cell proliferation in the equine endometrium during the oestrous cycle.

Cell proliferation and apoptosis are hormone-dependent physiological processes involved in endometrial growth and regression. The aims of the present study were: (1) to evaluate endometrial cell proliferation using proliferating cell nuclear antigen (PCNA) expression; (2) to evaluate the induction of endometrial cell death by the expression of active caspase-3 and the apoptotic phenotype visualised by DNA fragmentation; and (3) to relate these observations to endometrial tissue dynamics in the equine endometrium throughout the oestrous cycle. Endometria were assigned to follicular and luteal phases based on ovarian structures and plasma progesterone. Cell proliferation and active caspase-3-mediated apoptosis were expressed in both phases of the oestrous cycle. In the luteal phase, PCNA expression was higher than in the follicular phase. Highest PCNA activity was noted in the luminal and glandular structures. Active caspase-3 staining was increased in luminal epithelium and deep glandular cells during the luteal phase. However, in the follicular phase, stromal cells showed greater active caspase-3 expression. Only a few apoptotic endometrial cells were detected by terminal deoxyribonucleotidyl transferase-mediated dUTP-digoxigenin nick end-labelling (TUNEL) and these cells were mostly present in luminal and glandular structures. A simultaneous increase in DNA, cell proliferation and protein synthesis was observed in the endometrium during the mid-luteal phase. This suggests that cell hyperplasia occurs at the time the histotroph is needed for eventual embryo nourishment.

Esophageal replacement in rat using porcine intestinal submucosa as a patch or a tube-shaped graft.

This study compares the efficacy of porcine intestinal submucosa (SIS) patch graft versus SIS-tube graft in esophageal replacement, using a novel esophageal regeneration model. Clinical function, as well as macroscopic and microscopic morphology were evaluated in both SIS-treated groups. We performed semi-circumferential esophageal excision followed by repair of the defect using either a SIS-patch graft (group I) or segmental esophageal excision followed by a SIS-tube interposition graft (group II) in rats. The 28-day survival rate was significantly different between the SIS-treated groups (100% in group I vs. 0% in group II). Unlike the rats in group II, which died within the first postoperative month due to esophageal dysfunction, all surviving animals in group I resumed a normal solid diet within a few days after surgery, without signs of esophageal dysfunction and gained weight. Barium swallow studies showed no evidence of fistula, significant stenosis or diverticula. No hematological or serum biochemistry abnormalities were found. By day 150 the SIS patch was replaced by esophageal-derived tissues. In the rat model, a patch graft technique using SIS appeared to induce esophageal regrowth and provided an initial and long-term satisfactory function, while a tube-shaped graft technique using SIS was unsuccessful.

Progesterone receptors and proliferating cell nuclear antigen expression in equine luteal tissue.

Steroid hormones act via specific receptors, and these play an important physiological role in the ovary. The objective of this study was to evaluate the cellular distribution of progesterone receptors and their staining intensity in different equine luteal structures during the breeding season, as well as their relationship to luteal cell composition, cell proliferation pattern and plasma progesterone (P4) concentration. There was an increase in proliferating cell nuclear antigen (PCNA) expression in large luteal cells from the corpus hemorrhagicum (CH) to mid-luteal phase, followed by a decrease toward the late luteal stage. In the CH, the number of large luteal cells was lower than in other structures. Only large luteal cells showed positive staining for P(4) receptors. An increase in staining intensity for P(4) receptors was observed between CH and mid-phase corpus luteum, and CH and late-phase corpus luteum. Synthesis of P(4) started at a very early stage of the luteal structure and was accompanied by an increase in P(4) receptors and PCNA expression, and proliferation of large luteal cells, until mid-luteal phase. These data suggest that large luteal cells might play an important role in the regulation or synthesis of P(4) in equine luteal structures.