What are the glands referred to as when secretary granules leave cells by exocytosis with no loss of other cellular material

The correct option is Merocrine.

To understand why this is the correct answer, we can look at how different types of exocrine glands release their secretions. Exocrine glands are classified into three main groups based on their method of secretion: merocrine, apocrine, and holocrine.

1. Merocrine Glands:
In merocrine secretion, the secretory product is stored in membrane-bound secretory granules. These granules move to the apical surface of the cell, and their membranes fuse with the cell membrane. The contents are then released outside the cell via exocytosis. Crucially, during this process, there is no loss of cell membrane or cytoplasm. The cell remains completely intact. Examples include salivary glands and eccrine sweat glands.

2. Apocrine Glands:
In apocrine secretion, the secretory product accumulates near the apical portion of the cell. During secretion, this apical portion of the cytoplasm pinch off along with the secretory droplets. Thus, the cell loses a part of its cytoplasm and membrane, which is later repaired. An example is the mammary glands.

3. Holocrine Glands:
In holocrine secretion, the secretory product accumulates inside the cell. The entire cell then ruptures and dies to release its secretions, meaning the cell itself becomes the secretion. The sebaceous (oil) glands of the skin are a classic example.

4. Autocrine:
Autocrine refers to a mode of hormone or chemical signaling where a cell secretes a hormone or chemical messenger that binds to autocrine receptors on that same cell, leading to changes in the cell itself. It is not a classification of exocrine secretion mechanism based on cellular material loss.

Since the question describes a process where secretory granules leave cells by exocytosis with no loss of other cellular material, the correct term is Merocrine.