A micro-probe is inserted through the nipple pore to study the...

The pathway of milk secretion from the site of production to the exterior is:

Lumen of alveolus $\rightarrow$ Mammary tubule $\rightarrow$ Mammary duct $\rightarrow$ Mammary ampulla $\rightarrow$ Lactiferous duct $\rightarrow$ Exterior.

Since the micro-probe is inserted from the exterior (nipple pore) towards the site of milk production, it will traverse these structures in the reverse order.

The correct sequential order is:

Lactiferous duct (D) $\rightarrow$ Mammary ampulla (C) $\rightarrow$ Mammary duct (A) $\rightarrow$ Mammary tubule (E) $\rightarrow$ Lumen of alveolus (B).

Answer: D $\rightarrow$ C $\rightarrow$ A $\rightarrow$ E $\rightarrow$ B