Reagent cartridge, reagent cartridge set, and pathological specimen preparation device

A reagent cartridge, comprising:

• a drug solution storage section which has a light transmissive first window section and a drug solution chamber capable of storing a drug solution;
• a case section which holds the drug solution storage section movably in a first direction and has a light transmissive second window section, a drug solution flow path, and a nozzle section communicating with the drug solution flow path;
• a biasing unit which biases the drug solution storage section in a direction opposite to the first direction with respect to the case section;
• and
• a discharge mechanism for discharging a predetermined amount of the drug solution stored in the drug solution chamber from the nozzle section by the moving motion of the drug solution storage section in the first direction within a predetermined range, wherein
• the second window section is provided on a first side face of the case section, and
• the first window section and the second window section are disposed along a second direction crossing the first direction to form an optical path with respect to the drug solution chamber.