Which cells secrete testosterone in man?

Mast cells secrete

Which cells secretes androgens in man?

Peptic cells secrete:

Write 'True' or 'False' : Hypothalamus stimulate Leydig's cells to secrete testosterone.

Oxyntic cells secrete:

Which cell secretes antibody?

Which cells secrete the neurilemma?

Which cells secrete the medullary sheath?

Trypsinogen is an inactive enzyme of pancreatic juice. An enzyme, enterokinase, activates it. Which tissue/cells secrete this enzyme? How is it activated?