Osteoblasts__B -> Osteocytes__S
0 -> Pre_Osteoblasts__P
0 -> Pre_Osteoblasts__P
Pre_Osteoblasts__P -> Osteoblasts__B
Pre_Osteoblasts__P -> 0
Osteoblasts__B -> 0
0 -> Osteoclasts__C
Osteoclasts__C -> 0
Bone_volume__z -> 0
0 -> Bone_volume__z