Vestibular glands secrete

$A$ : The male urethra is longer than the female urethra.
$R$ : It carries both urine as well as semen.

The mammary glands are paired structures that contain the glandular tissue and variable amount of fat. The correct sequence of tissues involved in synthesis and flow of milk are

Location - function : Testis and Ovary

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

In vertebrates the nails are formed from