Full Characterization of Corpus Luteum Morphological Dynamics, Echotexture, and Blood Flow During Different Stages of the Follicular Wave in Spontaneously Non-Mated Female Camels (Camelus dromedarius)

This study was designed, for the first time, to fully characterize the corpus luteum's (CL) dynamics, echotexture, and ovarian blood flow on the ipsilateral side of the CL during different stages of the follicular wave in spontaneously non-mated camels (<i>Camelus dromedarius</i>) and to correlate the CL's size echotexture with Doppler parameters. Of 20 non-mated camels, only 7 exhibited spontaneous ovulation. B- and color-mode analyses of the CL were estimated; CL frozen image echotextures [CL echogenicity (CLE) and CL heterogeneity (CLH)] and ovarian artery (OV. A.) dynamics were recorded, and ultrasound scanning was performed. Blood sampling and progesterone (P4) levels were measured after ovulation. CL diameter and echotexture were elevated (<i>p</i> = 0.025 and <i>p</i> = 0.037) at the mid-maturation stage and compared to the early growth and late regression stages (1.03 ± 0.45/cm and 82.65 ± 2.87 for CLE and 33.65 ± 1.83 for CLH vs. 1.98 ± 0.88 cm; 66.52 ± 4.32 for CLE and 15.66 ± 0.25 for CLH vs. 1.02 ± 0.02 cm, 65.12 ± 2.66 for CLE, and 19.32 ± 1.33 for CLH), as those parameters are critical in the determination of CL activity. Ipsilateral OV. A. diameter increased (<i>p</i> = 0.021) in the mid-maturation and regression stages, with a significant elevation in Doppler velocities (<i>p</i> = 0.025) in the maturation stage, with a decline in Doppler indices (<i>p</i> = 0.013), while the contralateral side was not affected. Ipsilateral mean velocity (Vm; cm/s) and blood flow volume (BFV; mL/min) were increased in the mid-maturation stage (23.55 ± 0.66 cm/s and 25.62 ± 0.32 mL/min). CL diameter was positively correlated with the CL's total colored area/pixels (r = 0.81; <i>p</i> = 0.001), total colored area % (r = 0.93; <i>p</i> = 0.001), and OV. A. velocities (r = 0.96; <i>p</i> = 0.001). In addition, there was a positive correlation between CLH and OV. A.BFV (r = 0.89; <i>p</i> = 0.001). After spontaneous ovulation, the CL increases in diameter and reaches its peak on day 12, with an elevation in the P4 level at day 10, and the total colored area of the CL continues to elevate until day 14. Ipsilateral OV. A. blood flow is elevated and linked to changes that occur in the CL's total coloration %. Evaluating luteal function in camels presents several challenges due to the species' unique reproductive physiology.