156 man, his character made him a house-surgeon and later a partner in the anatomy school. He was the leading expert in the study of comparative anatomy, infectious diseases, and gunshot wounds [2,3]. 　John Hunter began to study on the descent of fetal testis with an interest in Baron von Haller’s observations. In 1762, Hunter confirmed the abdominal position of the fetal testes as well as the neurovascular supply and the cre- master or musculus testis (a more proper name, according to Hunter). Through postmortem dissection, he first ob- served that the testis descends generally around the eighth month. He also described the retractile testes, undescend- ed testes, and testicular ectopia. He did not agree with the current suggestion that the testis was forced into the scro- tum by the compressive force of respiration, or pulled by the cremaster muscle. Instead, he proposed the sig- nificance of gubernaculum as a helm or rudder for tes- ticular descent [4]. 　Although the precise cause of failure to descend has not been clearly understood at this time, his association of cryp- torchidism with faulty testis appears interesting, as he stated that: ‘‘when one or both testicles remain through life in the belly, I believe that they are exceedingly imperfect and probably incapable of performing their natural func- tions, and that this imperfection prevents the disposition for descent from taking place.’’ 　He believed in the necessity of treatment of undescended testis after a period of patient observation. He wrote ‘‘As this progress is very slow, especially when the testicle is creeping through the ring, a doubt often arises whether it is better entirely to prevent its passage or to assist it by ex- ercise or other means; and it would certainly be the best practice to assist it, if that could be done effectually and safely.” 　Hunter’s accurate description of fetal testicular descent made great progress in the understanding of cryptor- chidism. Although testicular decent and maldescent are now being explored on the molecular level, most of our knowledge on cryptorchidism is still based on his obser- vations. Furthermore, even though many theories such as abdominal pressure, endocrine factors, cremasteric mus- cle contraction and gravity have been proposed to explain testicular descent, none is more important than the gu- bernaculum as Hunter claimed more than 2 centuries ago. 　After the great discovery of Hunter, the discussion of the nature of the gubernaculum, the role of the cremaster, and the process of descent continued. 　In 1866 Thomas B. Curling summarized what was known at that time regarding undescended testicles in his book, A Practical Treatise on the Diseases of the Testis [5]. Some of his observations hold true today, such as abnormal testicular function in undescended testis and proper evolu- tionary time limits to recovery of retained testicles. He also summarized the possible cause of the retained testicle: ei- ther the defective development of the cremasteric muscle, adhesions secondary to peritonitis, or a contracted ex- ternal ring. Although he reported some misconceptions in Korean J Urol 2010;51:155-160 Park and Choi current understandings, his observations surely gave a theoretical basis on which later doctors attempted the first orchiopexy. UNDERSTANDING AND CONTROVERSIES ABOUT GUBERNACULUM The structure of the gubernaculum, or genitoinguinal liga- ment, was first described and named by Hunter in 1762. Although most authors believe that it contributes sig- nificantly to testicular descent, there is little consensus on the mechanism involved. Controversies around gubernac- ulum were related to its tail structures and its role in the development of ectopic testis. 　In 1840, Curling noted the gubernaculum to be a soft, sol- id protruding body that varied in shape and size at different stages of testicular descent [6]. He also claimed that the gu- bernaculum terminated in three muscular processes, which he could trace before, during and after testicular descent. He listed these as (i) external - connected to Poupart’s ligament; (ii) middle - through the external ring to the bottom of the scrotum; and (iii) internal - to the os pubis and the rectus muscle sheath. 　Since the gubernaculum contains muscle that is likely to contract, this led Lockwood to propose the ‘traction theo- ry’ of testicular descent. Following the examination of eight fetuses (7 weeks’ gestation to full term), he noted the change of distal gubernaculum from a soft, jelly- like mass into a leash of fibers that spread out to several areas and pulled the testis into the scrotum [7]. Sometime later, his description of the fibers became known as the ‘tails of Lockwood’ and the presumed cause of testicular ectopia (Fig. 1) [8]. Although Lockwood himself did not mention that abnormal development of the gubernacular tail could be the cause of testicular ectopia, some authors referred to Lockwood’s work as an explanation for testicular ectopia [9-11]. 　In the early 20th century, the concept of gubernacular tails as a cause of testicular maldescent prevailed. Coley found many similarities between Curling’s and Lock- wood’s theories and tried to amalgamate both theories [12]. 　Some authors reported findings in conflict to the “tails of Lockwood.” Sonneland could not find any corroborative evidence either embryological or anatomical for the ex- istence of multiple processes [9]. Instead of multiple gu- bernacular tails, he claimed a singular gubernacular proc- ess and believed that the fibrous attachment of ectopic tes- tis was just a result and not the cause of testicular maldescent. McGregor also failed to find any subdivision of the gubernaculum and concluded that Lockwood’s theo- ry was unproved and proposed the ‘third inguinal ring’ or congenital fascial packets or barriers as a cause of tes- ticular ectopia [13,14]. 　Backhouse proposed his own theory regarding the gu- bernaculums [15]. He described the gubernaculum as con- sisting only of mesenchyme (not muscles and fibers, as pre- vious believed), which formed a column in the abdomen at-