German postage stamp from 1991, commemorating 750 years of the apothecary profession The<unk> , or<unk> ' weights and measures, is a historical<unk>  of mass and volume units that were used by physicians and<unk>  for medical recipes and also sometimes by scientists. The English version of the<unk>  is closely related to the English troy<unk>  of weights, the pound and grain being exactly the same in both. It divides a pound into 12 ounces, an ounce into 8 drachms, and a drachm into 3 scruples of 20 grains each. This exact form of the<unk>  was used in the United Kingdom; in some of its former colonies, it survived well into the 20th century. The<unk>  of measures is a similar<unk>  of volume units based on the fluid ounce. For a long time, medical recipes were written in Latin, often using special symbols to denote weights and measures. The use of different measure and weight<unk> s depending on the purpose was an almost universal phenomenon in Europe between the decline of the Roman Empire and metrication. This was connected with international commerce, especially with the need to use the standards of the target market and to compensate for a common weighing practice that caused a difference between actual and nominal weight. In the 19th century, most European countries or cities still had at least a "commercial" or "civil"<unk>  (such as the English avoirdupois<unk>  for general trading, and a second<unk>  (such as the troy<unk>  for precious metals such as gold and silver. The<unk>  for precious metals was usually divided in a different way from the commercial<unk> , often using special units such as the carat. More significantly, it was often based on different weight standards. The<unk>  often used the same ounces as the precious metals<unk> , although even then the number of ounces in a pound could be different. The<unk> ' pound was divided into its own special units, which were inherited (via influential treatises of Greek physicians such as Dioscorides and Galen, 1st and 2nd century) from the general-purpose weight<unk>  of the Romans. Where the<unk> ' weights and the normal commercial weights were different, it was not always clear which of the two<unk> s was used in trade between merchants and<unk> , or by which<unk> <unk>  weighed medicine when they actually sold it. In old merchants' handbooks, the former<unk>  is sometimes referred to as the pharmaceutical<unk>  and distinguished from the<unk> . __TOC__
Apothecaries' system
Endocrine system
Immune cycle
Hypothalamic–pituitary–gonadal axis
Ovarian reserve
Dermatome
Dermatome 
Hypothalamic–pituitary–prolactin axis