The aim was to study number, volume, apoptosis of corpora lutea (CL), and serum P₄ concentrations in early, middle, and late diestrus of dogs. Thirty-six bitches were ovari-hysterectomized (OVX): Early Diestrus (Group [G]1; OVX 20 days after end of estrus [DEH]); Mid-diestrus (GII; OVX between 21 and 40 days after DEH), and Late-diestrus (GIII; OVX between 41 and 60 days after DEH). Before OVX a blood sample was collected to quantify P₄. After OVX, the number of CL (NCL) was recorded, CL measured using both ultrasonography (US) and caliper (CAL), and the volume (mm³) was calculated. Based on abundances of caspase-3, apoptotic luteal cells were detected. Bitches in early-diestrus had greater P₄ concentrations than bitches in mid- and late-diestrus (23.52 ± 3.78 and 10.86 ± 3.88 ng/mL; P < 0.05). The NCL, cumulative USCLV, and CALCLV were similar among diestrus stages (P > 0.30). Bitches with CL (≥5) had twice the serum P₄ concentrations as bitches with CL1−2 and CL3−4 (22.71 ± 3.70 and 10.97 ± 4.06 ng/mL; P < 0.05). There were correlations between P₄ concentrations with USCLV, CALCLV, and NCL (r = 0.64, r = 0.67, r = 0.44; P < 0.0001). When serum P₄ concentrations were adjusted for stages of diestrus, however, there were only correlations during early diestrus. The percentage of apoptotic cells was greater in GIII compared with GI and GII (13.75 ± 2.26 % compared with 4.5 ± 0.68 % and 4.6 ± 1.5 %, respectively; P < 0.05). As days of diestrus increased, number of apoptotic cells increased, and serum P₄ concentrations decreased.

目的是研究犬发情期早期、中期和晚期黄体（CL）的数量、体积、凋亡和血清 P ₄浓度。36 只母犬进行了卵巢子宫切除术 (OVX)：早发情（组 [G]1；发情结束后 20 天的 OVX [DEH]）；发情中期（GII；DEH 后 21 到 40 天之间的 OVX）和发情后期（GIII；DEH 后 41 到 60 天之间的 OVX）。在 OVX 之前收集血液样本以量化 P ₄。OVX 后，记录 CL (NCL) 的数量，使用超声 (US) 和卡尺 (CAL) 测量 CL，并计算体积 (mm ³ )。基于 caspase-3 的丰度，检测到凋亡的黄体细胞。发情早期的母犬有更高的 P ₄中后期发情期的浓度比母犬高（23.52 ± 3.78 和 10.86 ± 3.88 ng/mL；P  < 0.05）。NCL、累积 USCLV 和 CALCLV 在发情期之间相似（P  > 0.30）。CL (≥5) 母犬的血清 P ₄浓度是 CL1-2 和 CL3-4 母犬的两倍（22.71 ± 3.70 和 10.97 ± 4.06 ng/mL；P  < 0.05）。P ₄浓度与 USCLV、CALCLV 和 NCL之间存在相关性（r  = 0.64，r  = 0.67，r  = 0.44；P  < 0.0001）。当血清 P ₄浓度根据发情期进行了调整，但是，只有在发情期早期才有相关性。与 GI 和 GII 相比，GIII 中的凋亡细胞百分比更高（13.75 ± 2.26 %，分别为 4.5 ± 0.68 % 和 4.6 ± 1.5 %；P  < 0.05）。随着发情天数的增加，凋亡细胞数量增加，血清P ₄浓度降低。