Fruit anatomy 

The pericarp is typically made up of three distinct layers: 

1 The exocarp, which is the outermost layer. The exocarp forms the tough outer skin of the fruit, if there is one. 

2 The mesocarp, which is the middle layer. The mesocarp (from Greek: meso-, "middle" + -carp, "fruit") is the fleshy middle layer of the pericarp of a fruit; it is found between the exocarp and the endocarp. It is usually the part of the fruit that is eaten.

3 The endocarp, which is the inner layer surrounding the ovary or the seeds. The endocarp is a botanical term for the inside layer of the pericarp (or fruit), which directly surrounds the seeds. It may be membranous as in citrus where it is the only part consumed, or thick and hard as in the stone fruits of the family Rosaceae such as peaches, cherries, plums, and apricots.