Fimbrial capture of the ovum and tubal transport of the ovum in the rabbit, with emphasis on the effects of beta 2-adrenoreceptor stimulant and prostaglandin F2 alpha on the intraluminal pressures of the tubal ampullae

Embryo transfer in buffalo (Bubalus bubalis)

The use of assisted reproductive technologies, such as superovulation and in vivo embryo production and in vitro embryo production (IVEP), has increased rapidly in recent years and is now applied worldwide for genetic improvement in beef and dairy buffaloes. Although in vivo embryo production has been shown to be feasible in buffalo, low efficiency and limited commercial application has been documented. These results could be associated with low antral follicle populations, high levels of follicular atresia and/or failures of the oocyte to enter the oviduct after superovulation. Additionally, IVEP technology has been shown to be an important tool for multiplying genetic material from donors of superior merit, and promising results have been achieved with the use of ovum pick-up (OPU) along with IVEP in buffalo. However, several factors appear to be critical for successful OPU/IVEP, including circulating levels of anti-Müllerian hormone, antral follicle populations, sizes of the follicles available for the OPU, reproductive seasonality, semen (sire) used for IVEP, donor category and farm. Furthermore, technologies applied to control follicular wave emergence and ovulation at predetermined times, without the need for estrus detection in recipients, has facilitated management and improved the efficiency of embryo transfer programs in buffalo herds. Conclusively, with the considerable evidence of poor results with in vivo embryo production in buffaloes, the association of OPU with IVEP represents a new alternative for the exploitation of buffalo genetics.

Administration of PGF2α during the periovulatory period increased fertilization rate in superovulated buffaloes

The aim of the present study was to determine the recovery of embryonic structures (ova/embryos) and fertilization rate in superovulated buffaloes treated with PGF_2α during the periovulatory period. On day 0 (D0), buffaloes at random stages of the estrous cycle were treated with an intravaginal progesterone device (P4; 1.0 g) and estradiol benzoate (EB, 2.0 mg i.m.). From D4 to D7, all buffaloes received i.m. FSH (200 mg total) twice-daily over 4 days in decreasing doses. On D6 and D7, the animals were given PGF_2α analogue (0.53 mg i.m. sodium cloprostenol) and the P4 device was removed on D7. On D8, all buffaloes received GnRH (20 μg i.m. buserelin acetate). Buffaloes were then randomly allocated to one of three groups: control (Group C, n = 18), no further treatment; PGF_2α analogue injection (Group IM-PGF; n = 18), four injections (0.53 mg i.m. sodium cloprostenol) 12 h apart, from D8 to D10; PGF_2α analogue osmotic pump (Group OP-PGF; n = 18), s.c. osmotic mini-pump (2.12 mg sodium cloprostenol) from D8 to D10. The study had a crossover design (three treatments x three replicates). All animals underwent timed AI, 12 and 24 h after treatment with GnRH. Embryonic structures were recovered on D14. Ovarian ultrasonography was used on D8 and D14 to record follicular superstimulation and superovulatory responses. Blood samples were obtained on Days 7, 8, 9 and 10 to measure circulating concentrations of P4, E2 and PGFM. Data were analyzed by GLIMMIX procedure of SAS®. There was no effect (P = 0.58) of treatment on the total number of embryonic structures (Group C, 2.1 ± 0.8; Group IM-PGF, 2.1 ± 0.6; Group OP-PGF, 1.4 ± 0.4). There was also no effect (P = 0.93) of treatment on the recovery rate of embryonic structures (oocytes and embryos D14/CL D14). The fertilization rate was higher (P = 0.04) in Groups IM-PGF (84.6%) and OP-PGF (88.0%), which did not differ, than Group C (63.2%). The viable embryos rate was greater (P < 0.01) for Groups IM-PGF (82.0%) and OP-PGF (88.0%) than Group C (52.6%). There was no interaction between treatment and time and treatment effects for P4, E2 and PGFM concentrations. The findings showed that treatment with PGF_2α during the periovulatory period has potential to increase fertilization rate and embryo production in superovulated buffaloes.

Essential role of ZP molecules in tubal transport of embryos in mice

Our understandings of the molecular and cellular mechanisms underlying tubal transport of embryos are poor. This study describes the essential role of the molecules on the zona pellucida (ZP) in the tubal transport of mouse embryos. The bovine and porcine embryos that were interspecifically transferred to the mouse oviduct were selectively retained in the oviduct and rarely transported to the uterus. Antiserum ZP3-9 against synthetic peptides that are specific for mouse ZP3, significantly interfered with tubal transport of the treated embryos. The treatment of mouse embryos with antiserum ZP2-20 against the synthetic peptides, deduced from the sequences that are conserved in the structure of ZP2 from mouse and human, also inhibited their tubal transport. Among various proteolytic and glycosidic enzymes, treatments with trypsin and beta-glucosidase prior to transfer to the oviduct, significantly interfered with the tubal transport of the enzyme-treated mouse embryos. We hypothesize that species-specific epitopes on the ZP may be recognized by the oviductal cilia and/or the epithelial cells of ducts for tubal transport.

Investigation of ovum transport in the oviduct: the dynamics of oviductal fluids in domestic rabbits

Ova are captured by the oviductal fimbria and rapidly transported to the ampullary-isthmic junction of the fallopian tube. Fertilized ova and oviductal fluids are then carried medially in the fallopian tube, while undergoing maturation in preparation for entering the uterine cavity, where nidation and further development take place. This movement of oviductal fluids was visualized in a rabbit model with human chorionic gonadotropin-induced ovulation, by injection of a contrast medium into the ampulla region of the oviduct. In the ampulla, the opaque medium was observed to oscillate at 0-85.4 mm/s. This medial transport of the fluid towards the uterus decreased to 0-9.6 mm/s in the isthmic portion of the tube. This decrease substantiates previous findings that the transport of material in the isthmic portion of the oviduct is more strongly under the control of ciliary action than under peristaltic activity.