Which is the correct pathway for the secretion and transport of milk?

The correct answer is Option (3) → Alveoli, mammary tubules, mammary duct, mammary ampulla, lactiferous duct.

Milk is made in the alveoli, the clusters of cells inside each mammary lobe. From there it moves through a series of channels to the nipple: alveoli → mammary tubules → mammary duct → mammary ampulla → lactiferous duct.

Option (1) Mammary ampulla, mammary duct, mammary tubules, lactiferous duct, alveoli. — Incorrect. This order starts at the mammary ampulla and ends at the alveoli. It runs backwards, since milk is made in the alveoli and leaves through the lactiferous duct.

Option (2) Mammary tubules, lactiferous duct, mammary ampulla, alveoli, mammary duct. — Incorrect. This order places the lactiferous duct second and the alveoli fourth. Milk cannot reach the lactiferous duct before it is even made in the alveoli.

Option (3) Alveoli, mammary tubules, mammary duct, mammary ampulla, lactiferous duct. — Correct. Milk is made in the alveoli and leaves through the lactiferous duct; the tubules join to form ducts, and the ducts join to form the wider ampulla. Only this option keeps that order.

Option (4) Lactiferous duct, alveoli, mammary tubules, mammary duct, mammary ampulla. — Incorrect. This order starts at the lactiferous duct, which is the last channel, not the first. It also ends at the ampulla instead of the lactiferous duct.

NCERT Extract:
The Female Reproductive System – “… The glandular tissue of each breast is divided into 15-20 mammary lobes containing clusters of cells called alveoli (Figure 2.4). The cells of alveoli secrete milk, which is stored in the cavities (lumens) of alveoli. The alveoli open into mammary tubules. The tubules of each lobe join to form a mammary duct. Several mammary ducts join to form a wider mammary ampulla which is connected to lactiferous duct through which milk is sucked out.”

Figure 2.4 A diagrammatic sectional view of Mammary gland