Relationship between follicle size and ultrasound-guided transvaginal oocyte recovery.
We evaluated the relationship between follicle size and oocyte recovery (OR) using ultrasound-guided follicle aspiration. Thirty Holstein cows were subjected to OR without gonadotrophic therapy. Oocytes were recovered two to four times from each cow in a total of 67 aspiration sessions. Ovarian follicles with diameters < or =4 mm and >4 mm were aspirated in separated groups. Recovered oocytes from each group were kept separate and submitted to in vitro maturation, fertilization, and culture to the blastocyst stage. A total of 430 follicles were aspirated, of which 154 (35.8%) were from follicles >4 mm and 276 (64.2%) were from follicles < or =4 mm. Seventy-seven oocytes (50%) were recovered from follicles >4 mm and 200 (72.2%) were from follicles < or =4 mm. Nineteen blastocysts were obtained from follicles >4 mm, whereas 45 blastocysts were obtained from follicles < or =4 mm. Recovery rate was greater (P<0.01) in follicles < or =4 mm. Oocyte quality, cleavage rate and blastocyst development did not differ between different follicle sizes. Routine aspiration of small follicles (< or =4 mm) could increase the number of oocytes available for in vitro development.
Seneda
M M
MM
Department of Clinical Veterinary, CCA, UEL, PR 86051-990, Londrina, Brazil. mseneda@uel.br
Esper
C R
CR
Garcia
J M
JM
Oliveira
J A
JA
Vantini
R
R
D000818:Animals; D001755:Blastocyst; D002417:Cattle; D005260:Female; D005307:Fertilization in Vitro / Q000662:veterinary; D009865:Oocytes / Q000502:physiology; D006080:Ovarian Follicle / Q000033:anatomy & histology*; D013396:Suction; D020858:Tissue and Organ Harvesting / Q000379:methods*; D014463:Ultrasonography