الفهرس | Only 14 pages are availabe for public view |
Abstract Studies on different aspects of reproduction of the camels are urgently needed to disclose the possibilities of improving reproductive and productive capabilities of this important species. The current work aimed to study the follicular wave pattern, hormonal profiles and to investigate the efficacy of inducing ovulation using GnRH analogue. In addition, the changes in blood vasculature of the ovarian follicles and corpus luteum during different developmental stages were studied. Three reproductively sound, non pregnant, non lactating female dromedary camels were used in the present study. The animals were examined ultrasonographically, in a daily basis, using B-mode and color Doppler to detect the changes in ovarian structures and their blood vasculature, respectively, for 22 follicular cycles. Camels were bled daily to trace the hormonal changes relative to the structural changes of the ovary. During each follicular cycle, the interwave interval, day of emergence, deviation, and ovulation, maximum diameter of the dominant follicle, detection and regression of the CL were determined. Blood area and percentage were determined in the ovarian structures. A single injection of GnRH analogue was used to induce ovulation for dominant follicles over 0.9 cm. E2 and P4 were assayed during each studied reproductive phase during the present study. The results showed that, three phases of follicular development were noticed during each follicular wave including, growth (11.6 ± 0.8 days), mature (6.9 ± 0.6 days) and regression (13.3 ± 1.3 days) phases. The mean total number of recruited follicles was 16.5 ± 1.8. The follicular wave lasted for 35 ± 2.3 days. In approximately 70.8 % of the studied waves, the dominant follicle reached a mean maximum diameter of 21.6 ± 0.6 mm whereas in the other 29.2 % of the waves, the follicle continued to grow until it reached a mean maximum diameter of 40.6 ± 3.2 mm. Estrous behavior was unpronounced and highly variable in duration and intensity. The mean diameter of the DF at the day of emergence was 4.6 ± 0.2 mm versus 4.1 ± 0.3 mm for the subordinate. The day of deviation was determined on day 6.1 ± 1.08. The mean diameter of the DF at the day of deviation was 9.9 ± 0.4 mm versus 8.3 ± 0.4 mm for the subordinate follicle. The mean maximum diameter of the subordinate follicle was 8.6 ± 0.3. The regression of subordinate follicle started on Day 8.1 ± 1.3. An ovulation rate of 100 % was recorded with the GnRH treatment when the maximum size of the dominant follicle measured between 9.2–18.9 mm. Treatment was noticed to shorten the interwave interval from 17.03 ± 0.8 to 11.7 ± 1.7 days. Ovulation occurred within 24–32 h of treatment in 92.3 % of trials and within 32–40 h of treatment in 7.7 % of trials. The induced CL attained its maximum diameter on day 9.9 ± 0.9. The corpus luteum lasted for 24.2 ± 1.9 days. Estradiol increased from basal levels of 27.4 ± 0.4 pg/ml to peak concentrations of 134.4 ± 47.5 pg/ml as the follicle reached a diameter of 13.2 mm then decreased until the next wave of follicular growth. Peripheral concentrations of progesterone remained low (less than 0.4 ng/ml) throughout the follicular wave. Following induction of ovulation, concentrations of progesterone increased gradually to reach a mean peak concentrations of 15.9 ± 7.3 ng/ml by day 9 and decreased thereafter until the complete regression of the CL. The blood flow of ovulatory follicles detected for the first time when the diameter was 6.9 ± 0.8 mm (day 4.0 ± 0.5). The vascularized area increased gradually with the growth of the follicles. At 8 hr before ovulation, the maximum diameter of the follicle was 15.8 ± 0.7 mm, with BA and BA% of 0.19 ± 0.04 cm2 and 9.8 ± 2.6 %, respectively. BA and BA% decreased gradually with regression of the follicles to disappear completely on day 27 ± 1 when the diameter of the DF was 16.1 ± 0.5 mm. The blood flow to the oversized follicle wall increased gradually till reached the maximum value of 0.34 ± 0.05 cm2 when the size of the follicles was 26.7 ± 4.6 mm, but the BA% was decreased till reached 4.1 ± 0.2 %. Then both the BA and BA% decreased for few days inspite of the follicle continued to grow. Blood circulation in the CL was detected in all ovulations starting from day 1 after ovulation. The blood flow to the CL rose distinctly after ovulation till reached the maximum when the CL was 13.8 ± 1.01 mm in diameter (day 5) while the maximum BA noticed when the CL was 18.1 ± 0.4 mm in diameter (day 7). On day 10 both, the BA and BA% decreased to 0.33 ± 0.01 cm2 and 19.8 ± 6.7 %, respectively concomitant with beginning of regression of the CL, then both, the BA and BA% decreased gradually before completely disappeared on day 22. On the scope of the present study we concluded that 1. The follicular wave pattern in dromedaries consists of well defined, but individually variable, periods of growth, maturity and regression. 2. The dominant follicle is larger than that of subordinate follicle in the day of emergence (with few exceptions) and deviation. 3. Ovarian follicles best respond to induction of ovulation using GnRH analogue when their size ranges from 9-19 mm. No ovulation occurred from follicles larger than 30 mm diameter. 4. There is a close temporal relationship between luteal diameter and serum progesterone concentration after induced ovulation. 5. Doppler ultrasound could provide new information on the development of the follicle towards ovulation, allowing visual observations of the blood flow in a delimited area in the walls of preovulatory follicles and CL in camels. |