Which Tanner stage describes males with a testicular volume of less than 1.5 ml?

The Tanner stages are a classification system that describes the physical development of children, adolescents, and adults, particularly during puberty. In males, Tanner stage I denotes prepubertal genitalia. At this stage, the testicular volume is less than 1.5 ml, indicating minimal or no testicular development.

In Tanner stage I, there are not yet any significant secondary sexual characteristics, and the penis and testicles remain small. This stage reflects the early phase of sexual development before hormonal changes initiate the growth of the testicles and other genitalia.

As puberty progresses into Tanner stage II and beyond, testicular volume and size increase, along with the development of secondary sexual characteristics. Thus, the specified characteristic of a testicular volume of less than 1.5 ml is specifically indicative of Tanner stage I. Understanding the Tanner stages helps healthcare providers assess and monitor the normal progression of puberty in males.