Endocrine glans are referred to as ductless glands because they release the hormones directly into the blood stream. They do not have any ducts for their secretion. 

Insulin.

Pituitary gland is attached to brain.

Y Chromosome determines the sex of the individual. The presence of Y chromosome forms a male (XY) while the absence of it indicates a female (XX).

Thyroxine hormone controls metamorphosis in frogs.
Insect hormones control insect metamorphosis.