The mammary gland is a modification of which of the following glands in Eutherians?

Write a note on the structure of mammary glands.

In a pregnant woman having prolonged labour pains,if childbirth has to be hastened,i.e.,to aid parturition,it is advisable to administer a hormone that can:

$A$: Oxytocin acts on the uterine muscles and causes stronger uterine contractions,which in turn stimulates further secretion of oxytocin.
$R$: Oxytocin is released from the maternal pituitary.

Parturition is

Lactiferous duct is present in