Primers are short pieces of DNA that are made in a laboratory. Since they're custom built, primers can have any sequence of nucleotides you'd like. In a PCR experiment, two primers are designed to match to the segment of DNA you want to copy.
One of the first symptoms of trigger finger is soreness at the base of the finger or thumb. The most common symptom is a painful clicking or snapping when bending or straightening the finger. This catching sensation tends to get worse after resting the finger or thumb and loosens up with movement.
Trigger finger is the popular name of stenosing tenosynovitis, a painful condition in which a finger or thumb locks when it is bent (flexed) or straightened (extended). Tendons are tough, fibrous cords that connect muscles to bones. Tendons must slide easily through their protective coverings (tendon sheaths).