A Gracia-Molina’s research while affiliated with University of Las Palmas de Gran Canaria and other places

The aim of the first experiment was to determine the plasma concentrations of LH and progesterone in seven ewes of the Canarian breed during the follicular phase of a synchronized cycle. In the second experiment, cyclic ewes of the Canarian breed were bilaterally ovariectomized on the Days 1 (n = 3), 2 (n = 3) and 3 (n = 3), Day 0 being the day of withdrawal of the sponges. All the follicles greater than 1 mm in diameter were dissected out and their follicular quality was determined by histological examination of their degree of atresia throughout the experimental period. The duration of the LH surge (values >5 ng/ml) was 14.12 +/- 0.36 h and the preovulatory peak of secretion of LH averaged 56.3 +/- 1.9 ng/ml. The plasma levels of progesterone were basal (<0.5 ng/ml) from 48 h before LH peak until 48 h after it. During the follicular phase, 61.8% of the follicles greater than 1 mm in diameter were atretic (63 versus 39; p < 0.01), with the highest level of atresia in the first 2 days of the follicular phase; no significant differences were found between early atresia and advanced atresia in the experimental study period as a whole. In small follicles (1-2 mm. in diameter) there was a normal follicles majority (24 versus 13; p < 0.05); in medium follicles (2-4 mm. in diameter) the number of atretic follicles was very high (42 versus 8; p < 0.01), with a constant rate of atresia throughout the 3 days of the follicular phase; in large follicles (>4 mm. in diameter) the number of normal follicles was quite similar to the number of atretic follicles (7 versus 8; p > 0.1).

The objective of the study was to identify the effects of LH on the final follicle maturation process as well as the incidence of atresia during the follicular phase of the goat's estrous cycle. In Experiment 1, concentrations of the LH were measured during the follicular phase of a synchronized cycle in 8 Canary goats. In Experiment 2, the same animals were synchronized again. On each day of a 4-day experimental period (day 0 = day of sponges withdrawal), 2 of the goats were bilaterally ovariectomized. Follicles with a diameter > 1 mm were dissected out to obtain qualitative histological data in normal, early atretic I, early atretic II, advanced atretic I and advanced atretic II follicles. The total interval from sponge withdrawal to LH peak was 77.5 +/- 9.8 h. LH peak concentration averaged 44 +/- 5.3 ng/ml and the mean length of the preovulatory surge (amounts over 10 ng/ml) was 8.9 +/- 0.9 h. During the total follicular phase, there were more atretic follicles than normal follicles (58 vs. 30, P < 0.05). The number of early and advanced atretic follicles was similar. There were more early atresia I than early atresia II follicles (23 vs. 6, P < 0.05). On day 2, the number of advanced atretic follicles was greater than early atretic follicles (10 vs. 4, P < 0.05). There was an increase in the number of early atretic follicles from day 2 to day 4 (4 vs. 9, P < 0.05), which was consistent with the effects of the preovulatory LH surge.