An illustration of the adapted OPU system. A 0.25 mL semen straw (4) was placed between the Teflon circuit (2) and the needle (6). To connect the straw, a small silicone tube (3) was used to hold one tip to the circuit, while the other tip was directly connected to the needle (6). For follicles from 7.5 to 8.5 mm in diameter, a second 0.25 mL semen straw was placed between the first straw (4) and the needle (6). The cotton plug of the second straw was removed and another small silicone tube was used to connect the two semen straws. 1, needle guide; 2, Teflon circuit; 3, silicone tube; 4, 0.25 mL semen straw; 5, needle adapter; 6, 20G needle.