Were there any cases so far that lack of or absence of testis by birth??

Yes: Unfortunately this has occurred, though it is EXTRAORDINARILY RARE. Testosterone is given as hormone therapy to try to replicate normal function. A testicle prosthesis can be placed for aesthetic/cosmetic purposes.

? is question: Not exactly sure what the question is. An absent testicle on one side is not unusual. There can be undescended testicles. This means they are present, but just haven't dropped into the scrotum yet. If the testicles are not found in the scrotum or the abdominal cavity, then the infant needs a workup for ambiguous genitalia.

Confusing question: The testis form near tissue that forms the kidneys & make a gradual descent toward the lower body during fetal development. They usually make a final move into the scrotum during the last weeks of pregnancy. Some don't make the full journey & can be found in the abdomen. Rarely a testis will twist during travel, cut its own blood supply and die.