What does “merocrine mode of secretion” mean?

What does “merocrine mode of secretion” mean?

1. secret is discharged with complete destruction of glandulocytes


2. secret is discharged with destruction of microvilli of glandulocytes


3. secret is discharged with destruction of apical pole of glandulocytes


4. secret is discharged to the blood


5. *secret is discharged without destruction of glandulocytes