Short answers, pulled from the story.
The testicle serves as the male gonad and acts as the primary engine for sperm production and the secretion of androgens, primarily testosterone. It functions as an internal organ homologous to the female ovary yet diverging into distinct functional paths for male reproduction.
The testicle maintains an optimal temperature of 34.4 degrees Celsius, which is slightly less than the core body temperature of 36.7 degrees Celsius. The cremasteric muscle contracts to move the testicles closer to the body for warmth or relaxes to lower them away from the body for cooling.
The average adult testicle measures up to 18 cubic centimeters, with a normal volume ranging between 15 and 25 cubic centimeters. This volume is directly proportional to sperm production, as larger testicles contain more seminiferous tubules and Sertoli cells.
The sex-specific gene SRY on the Y chromosome initiates sex determination at about week 6 of embryonic development. This process leads to the development of the male phenotype through downstream regulation of sex-determining factors such as GATA4, SOX9, and AMH.
Testicular torsion has a 90% chance to save the testicle if de-torsion surgery is performed within six hours of onset. This medical emergency requires immediate intervention to prevent severe trauma affecting the tunica albuginea.
Testicular size varies widely across the mammalian kingdom, with the right whale having the largest testes weighing around 500 kilograms. Human testicular size falls between the extremes of gorillas at 0.03% and chimpanzees at 0.3% of body weight.