The number of laticiferous ducts that open into the nipple is

Breast is a compound tubulo-alveolar gland which secretes milk. The gland consists of 15 to 20 lobes. Each lobe is a cluster of alveoli, and is drained by a lactiferous duct. The lactiferous ducts converge towards the nipple and open on it. Near its termination each duct has a dilatation called a lactiferous sinus. Ref - BDC Vol1 6th edition pg 34