In vitro developmental competence of buffalo oocytes collected at various stages of the estrous cycle.
The objective was to determine the in vitro developmental competence of buffalo oocytes collected from abattoir-derived ovaries at various stages of the estrous cycle and follicular status. In Experiment 1, ovaries (n=476 pairs) were collected and divided into the following five groups: (a) ovaries with a corpus hemorragicum and no dominant follicle (CH-NO-DF); (b) ovaries with a mature functional corpus luteum (CL) and a dominant follicle (CL-DF); (c) ovaries with a mature functional CL and no dominant follicle (CL-NO-DF); (d) ovaries with a regressing CL and a dominant follicle (RCL-DF); and (e) ovaries without any luteal structures and only small follicles (ANEST). In Experiment 2, 144 pairs of ovaries with a CL (or regressing CL) and a dominant follicle were collected and follicles were classified as dominant, largest subordinate, and subordinate. In both experiments, the dominant follicle was defined as any follicle >10mm in diameter that exceeded the diameter of all other (subordinate) follicles. Although oocytes were collected from each group of ovaries, only Grades A or B oocytes were used for in vitro embryo production. Cleavage rates were higher (P<0.05) from oocytes collected from ovaries in the CH-NO-DF (59.6%) and CL-NO-DF (59.2%) groups than those collected from CL-DF (52.2%) and ANEST (43.6%) groups. The yield of transferable embryos was higher (P<0.05) from oocytes collected from CH-NO-DF (27.4%) and CL-NO-DF (24.0%) ovaries than from CL-DF (16.2%), RCL-DF (15.4%), and lowest (P<0.05) from ANEST (8.8%). In Experiment 2, oocytes from the dominant follicle had a higher (P<0.05) cleavage rate (65.2 %) and transferable embryo yield (30.2%) than those collected from the largest subordinate and subordinate follicles. In conclusion, oocyte competence depended on the morphofunctional state of ovaries. Oocyte development was maximal in pairs of ovaries with a corpus hemorragicum or CL and no dominant follicle; in paired ovaries with a CL and a dominant follicle, development was maximal in oocytes derived from the dominant follicle.
Manjunatha
B M
BM
Veterinary College, Karnataka Veterinary, Animal and Fishery Sciences University, Bangalore 560024, India. drmanjunathvet@gmail.com
Gupta
P S P
PS
Ravindra
J P
JP
Devaraj
M
M
Ramesh
H S
HS
Nandi
S
S
D000818:Animals; D002020:Buffaloes / Q000502:physiology*; D002970:Cleavage Stage, Ovum / Q000502:physiology; D004624:Embryo Transfer; D030762:Estrous Cycle / Q000502:physiology*; D005260:Female; D008297:Male; D009865:Oocytes / Q000166:cytology / Q000254:growth & development*; D009866:Oogenesis / Q000502:physiology*; D006080:Ovarian Follicle / Q000166:cytology; D013997:Time Factors; D020858:Tissue and Organ Harvesting