Preantral follicle density in ovarian biopsy fragments and effects of mare age.

The aims of the present study were to: (1) evaluate preantral follicle density in ovarian biopsy fragments within and among mares; (2) assess the effects of mare age on the density and quality of preantral follicles; and (3) determine the minimum number of ovarian fragments and histological sections needed to estimate equine follicle density using a mathematical model. The ovarian biopsy pick-up method was used in three groups of mares separated according to age (5-6, 7-10 and 11-16 years). Overall, 336 preantral follicles were recorded with a mean follicle density of 3.7 follicles per cm2. Follicle density differed (P<0.05) among animals, ovarian fragments from the same animal, histological sections and age groups. More (P<0.05) normal follicles were observed in the 5-6 years (97%) than the 11-16 years (84%) age group. Monte Carlo simulations showed a higher probability (90%; P<0.05) of detecting follicle density using two experimental designs with 65 histological sections and three to four ovarian fragments. In summary, equine follicle density differed among animals and within ovarian fragments from the same animal, and follicle density and morphology were negatively affected by aging. Moreover, three to four ovarian fragments with 65 histological sections were required to accurately estimate follicle density in equine ovarian biopsy fragments.

Biomechanical properties of femoral posterior cruciate ligament fixations.

PURPOSE: The success of reconstructions of the posterior cruciate ligament (PCL) mainly depends on the fixation strength of the tendon-bone interface. Reliable data about the mechanical characteristics of PCL fixation techniques are sparse. The aim of this study was to investigate the biomechanical properties of different femoral PCL fixation techniques. METHODS: Fresh human cadaver quadriceps (Q) and hamstring (H) tendons were harvested and fixed into porcine femora with a press-fit fixation suturing the tendon over a bone bridge (group A), a novel implant post-fixation (group B) or an interference screw fixation (group C). Each group consisted of 10 specimens. The constructs were cyclically stretched and eventually loaded until failure. Elongation during cyclic loading, stiffness, failure mode and maximum failure load was evaluated. RESULTS: Elongation during cyclical loading was significantly larger between the 1st and the 20th cycle than between the 20th and the 500th cycle in all groups (p < 0.05). Maximum failure load was 409 ± 71 (336-517) N in group QA, 456 ± 58 (347-510) N in group QB, 548 ± 116 (400-798) N in group QC, 472 ± 114 N (316-676 N) in group HA, 494 ± 98 N (371-668 N) in group HB and 498 ± 87 N (391-687 N) in group HC (significantly higher for QB compared to QA, p < 0.05). CONCLUSION: This is the first study investigating the biomechanical properties of femoral PCL fixations. Implant-free fixation techniques like press-fit or post-fixations are able to withstand equal biomechanical forces compared to interference screw fixation. The novel fixations described in this study can be considered as a reliable alternative for the reconstruction of PCL using either hamstring or quadriceps tendons.

In vitro culture of equine preantral follicles obtained via the Biopsy Pick-Up method.

The objective was to conduct a preliminary evaluation of the efficacy of two media for in vitro culture of equine preantral follicles. Ovarian cortical strips were obtained from mares (N = 10) via the Biopsy Pick-Up method during the breeding season. Ovarian tissue was immediately submitted to histological analysis (noncultured control; D0) or cultured in situ for 1 day (D1) or 7 days (D7) in either α-MEM or TCM-199 and submitted to histological analysis, generating five treatment groups: noncultured control, α-MEM:D1, TCM-199:D1, α-MEM:D7, and TCM-199:D7. Preantral follicles were evaluated for follicle class (primordial, transitional, primary, and secondary) and morphology (normal vs. abnormal). A total of 142 preantral follicles were analyzed in five replicates. No follicles were observed in the TCM-199:D7 treatment group. The proportion of primordial follicles was higher (P < 0.03) in the control compared to the α-MEM:D7 treatment group. The proportion of primary follicles was higher (P < 0.04) in the α-MEM:D7 treatment group compared to the control. The proportion of developing follicles (transitional, primary, and secondary) was higher (P < 0.03) in the α-MEM:D7 treatment group compared to the control group. There was a greater (P < 0.004) percentage of morphologically normal developing follicles in the α-MEM:D1 treatment group compared to the TCM-199:D1 treatment group. Overall, the percentage of morphologically normal follicles was higher in the control group (72%; P < 0.02) and α-MEM:D1 group (84%; P < 0.0001) compared to the α-MEM:D7 (27%) treatment group. Mean follicle diameter was greater (P < 0.04) in the α-MEM:D7 treatment group (40.6 ± 1.1 µm) compared to the control group (37.3 ± 0.7 µm). Mean oocyte diameter was greater in the α-MEM:D1 (31.0 ± 0.7 µm; P < 0.006), TCM-199:D1 (30.7 ± 1.8 µm; P < 0.006), and α-MEM:D7 (33.2 ± 1.8 µm; P < 0.006) treatment groups compared to the control group (27.4 ± 0.9 µm). In conclusion, based on these preliminary data, in vitro culture of equine ovarian fragments obtained in vivo via the Biopsy Pick-Up method promoted preantral follicle development and follicle and oocyte growth in α-MEM for 7 days, with some follicles remaining morphologically normal throughout the culture period.

Equine preantral follicles obtained via the Biopsy Pick-Up method: histological evaluation and validation of a mechanical isolation technique.

The aims of this study in mares were to: (1) compare preantral follicle parameters between in vitro Biopsy Pick-Up (BPU) and scalpel blade collection methods and between histological and mechanical isolation processing (experiment 1); (2) histologically evaluate preantral follicles (experiment 2); and (3) compare histological analysis with a previously established mechanical isolation technique using a tissue chopper (experiment 3) for ovarian cortical fragments obtained in vivo using a BPU instrument. In experiment 1, preantral follicles were analyzed (N = 220; 90% primordial and 10% primary). Proportions of primordial and primary follicles did not differ (P > 0.05) between tissue collection (BPU vs. scalpel blade dissection) or processing (mechanical isolation vs. histology) methods. Follicle viability and morphology rates were similar (P > 0.05) between tissue collection methods, but mechanical isolation produced more (P < 0.05) morphologically normal follicles than histology. For experiment 2, preantral follicles (N = 332) were analyzed and primordial and transitional (combined) follicles and oocytes were 36.3 ± 0.3 and 26.1 ± 0.3 µm in diameter, respectively, and primary follicles and oocytes averaged 42.9 ± 1.8 and 31.8 ± 2.1 µm. For experiment 3 (188 preantral follicles), within the same animals, the proportion of primordial versus primary follicles was higher (P < 0.03) for histological analysis (98%) compared to tissue chopper analysis (94%), and number of follicles per mg of tissue was not affected (P > 0.05) by processing methods. In conclusion, most parameters evaluated for preantral follicles were similar between histological and tissue chopper processing techniques; hence, mechanical isolation efficiently dissociated equine preantral follicles from the ovarian cortex. Therefore, the tissue chopper could be used to isolate large numbers of morphologically normal equine preantral follicles for cryopreservation and/or in vitro culture.

Quantification, morphology, and viability of equine preantral follicles obtained via the Biopsy Pick-Up method.

A Biopsy Pick-Up (BPU) method was tested to determine the feasibility of retrieving preantral follicles from mare ovaries in vivo. A total of 33 ovarian biopsy procedures were performed on 18 mares during the breeding season. Mares were 5 to 21 years old and biopsies were performed during the estrous and/or diestrous phase, as confirmed by transrectal ultrasonography. Follicles were mechanically isolated using a tissue chopper, counted, and classified as normal or abnormal and primordial or primary. Viability of isolated follicles was determined by Trypan Blue dye. A total of 256 biopsy attempts were made resulting in 185 successful tissue sample collections (72% success rate). The mean weight of ovarian tissue collected per procedure was 25.0 ± 1.6 mg. Overall, 620 preantral follicles were collected and isolated (95% primordial and 5% primary). The mean (±SEM) number of follicles isolated per biopsy procedure was 18.8 ± 1.9. Primordial and primary follicles had an average diameter of 31.3 ± 6.2 and 41.1 ± 6.6 µm, respectively. Viability rate was higher (P < 0.001) for primordial follicles (91%) compared with primary follicles (50%). Primordial follicles tended (P < 0.06) to have a higher rate of morphological normality (96%) compared with primary follicles (80%). The total number of follicles isolated, amount of tissue harvested, and number of follicles per mg of tissue did not differ (P > 0.05) according to phase of the estrous cycle. Younger mares (5 to 7 years old) had more (P < 0.05) follicles isolated per procedure than older mares (14 to 21 years old). The length of the interovulatory interval was not affected (P > 0.05) by any biopsy procedure, and there were no adverse effects on cyclicity or general reproductive health. In conclusion, the BPU method provided large numbers of normal and viable preantral follicles for the study of early follicular development in mares. The BPU method might be used in the future to obtain preantral follicles for in vitro culture to enable the use of numerous oocytes present within the equine ovary. This could allow for the preservation of genetic material or large-scale embryo production.

Long-term in vitro culture of ovarian cortical tissue in goats: effects of FSH and IGF-I on preantral follicular development and FSH and IGF-I receptor mRNA expression.

Long-term in vitro culture (16 days) of caprine ovarian cortical tissue was performed to test the effect of FSH and IGF-I on the viability and development of preantral follicles and mRNA expression for FSH and IGF-I receptors. Fragments were cultured in α-MEM(+) alone or supplemented with different combinations of FSH and IGF-I (sequential medium). The culture period was divided into two parts. Follicles were isolated and classified as normal or abnormal and primordial, primary or secondary. Viability of isolated follicles was determined by staining with Trypan Blue dye. Expression of FSHR and IGFR-1 mRNA was evaluated by qPCR. At day 8 of culture, more (P < 0.05) follicles in treatments containing IGF-I alone or associated with FSH were normal and viable (overall mean, 81 % and 79 % respectively) than the treatments cultured with FSH or α-MEM(+) alone (68 % and 63 %). At day 16 of culture, treatments with FSH and/or IGF-I had more (P < 0.05) viable follicles (69 %) than α-MEM(+) (38 %). The percentages of follicular development observed in the IGF-I/FSH, FSH+IGF-I/FSH+IGF-I and FSH/IGF-I treatments were similar but higher (P < 0.05) than the other treatments. FSH and IGF-I during the entire culture period maximized (P < 0.05) follicular and oocyte diameters and the percentage of secondary follicles (28 %). FSHR mRNA expression in the non-cultured control was similar to the treatment supplemented with FSH and IGF-I but higher (P < 0.05) than α-MEM(+). IGFR-1 expression did not differ among treatments. Association of FSH and IGF-I in long-term in vitro culture promoted follicular development, maintaining FSHR mRNA expression.

Effect of insulin-like growth factor-I on some quality traits and fertility of cryopreserved ovine semen.

The objective was to evaluate the effects of insulin-like growth factor-I (IGF-I) on the quality and fertility of frozen/thawed ovine semen. Five rams (five ejaculates/ram) were used for evaluation of semen parameters. Before cryopreservation, ejaculates were divided into four aliquots and extended with Tris alone or supplemented with human IGF-I (50, 100, or 250 ng/mL). Semen was evaluated immediately after thawing (T0), after 1 h (T1) and 2 h (T2) post-incubation at 37 °C. The percentage of live cells (fluorescence analysis-calcein and ethidium), acrosome integrity (NAR) and motility were analyzed, and hypo-osmotic swelling tests (HOST) were used to evaluate membrane resistance. In addition, AI was performed using 121 ewes to compare the optimal concentration of IGF-I vs. Tris alone on pregnancy rates after laparoscopic insemination. Pregnancy diagnosis was performed by transrectal ultrasonography. After 1 and 2 h post-incubation, in every group, percentage motile sperm, NAR and HOST decreased compared to semen at T0. Motility was higher (P < 0.05) in the IGF-I 100 and IGF-I 250 groups when compared to the IGF-I 50 and Tris groups (76.2 and 74.4% vs. 66.2 and 64.4 percent, respectively) at T0, after 1 h (67 and 63.6% vs. 56.2 and 54.7%) and 2 h post-incubation (58.2 and 55.8% vs. 48 and 47.2%). Furthermore, viability was higher (P < 0.05) in the insulin-like growth factor-I (IGF-I) 100 and IGF-I 250 groups than in the IGF-I 50 and Tris groups (88.7 and 88.3% vs. 76.6 and 77.6%, respectively) at T0. There was no difference (P > 0.05) in NAR or hypo-osmotic swelling tests (HOST) among groups. There were no differences (P > 0.05) in fertility between the IGF-I 100 and Tris groups. In conclusion, IGF-I improved subjective sperm motility and structural integrity of the plasma membrane without a significant effect on 45-day pregnancy rates after laparoscopic insemination of ewes with frozen-thawed semen.

Effect of embryo age and recipient asynchrony on pregnancy rates in a commercial equine embryo transfer program.

In the present study, 809 uterine flushes and 454 embryo transfers performed in mares over a 4-yr interval were examined to evaluate the effects of: (1) the day of embryo collection on recovery rates; (2) the degree of synchrony between donor and recipient mares on pregnancy rates; (3) the recipient day post ovulation on pregnancy rates; and (4) the age of the embryo at recovery on pregnancy rates at 60 days. Uterine flushes were performed on Days 6, 7, 8, 9, and 10 (Day 0 = ovulation) and embryos were transferred to recipients with degrees of synchrony varying between +1 to -6 (recipient ovulated 1 day before through 6 days after the donor). Recipient mares ranged from 2 to 8 days post ovulation. Embryo recovery rates were similar for flushes performed on Day 7 (61%), Day 8 (66%), Day 9 (59%), and Day 10 (56%), but the embryo recovery rate was lower (P < 0.03) for flushes performed on Day 6 (42%) compared with all other days. Pregnancy rates for various degrees of synchrony were as follows: +1 (71%), 0 (77%), -1 (68%), -2 (63%), -3 (66%), -4 (76%), -5 (61%), and -6 (27%). The -6 day of degree of synchrony had the lowest (P < 0.05) pregnancy rate compared with all other days, but there was no significant difference among +1 to -5 days. There was a lower (P < 0.05) pregnancy rate for embryos transferred to recipient mares on Day 2 (33%) compared with mares on Day 3 (66%), Day 4 (66%), Day 5 (62%), Day 6 (55%), Day 7 (58%), and Day 8 (56%). Pregnancy rate was higher (P < 0.05) for Day 7 (76%) embryos compared with Day 6 (50%), Day 8 (64%), and Day 9 (44%) embryos; Day 9 embryos resulted in lower (P < 0.05) pregnancy rates than Days 7 or 8 embryos. In conclusion, this study demonstrated that: (1) embryo recovery rates between Days 7 and 10 were similar and acceptable (e.g., 63% 488/771); (2) the degree of synchrony between donor and recipient mares does not need to be as restricted as previously reported in horses. Acceptable pregnancy rates (e.g., 70%, 99/142) were obtained even when recipient mares ovulated 4 to 5 days after the donors; (3) similar pregnancy rates were obtained when recipient mares received embryos within a large range of days post ovulation (Days 3 to 8); and (4) Day 7 embryos produced higher pregnancy rates when compared with Days 8 and 9 embryos. In clinical terms, the application of these new findings will be beneficial to large equine embryo transfer operations in producing more pregnancies per season.