1. (

• meiosis ,
• miosis ,
• reduction_division

) (genetics) cell division that produces reproductive cells in sexually reproducing organisms; the nucleus divides into four nuclei each containing half the chromosome number (leading to gametes in animals and spores in plants) ;

2. (

• light_reflex ,
• pupillary_reflex ,
• miosis ,
• myosis

) reflex contraction of the sphincter muscle of the iris in response to a bright light (or certain drugs) causing the pupil to become smaller ;