How can the types of secretion (merocrine, eccrine, apocrine, holocrine) be distinguished?

So we can first distinguish glands from whether they release their secretions inward into the bloodstream (endocrine glands) or outward (exocrine No. Endocrine glands are e.g. hormone-producing glands such as the thyroid gland or the adrenal glands. Exocrine glands are, for example, tallow and sweat glands on the skin.

It is then possible to distinguish whether the gland cells release the gland secretion with parts or without parts of the cell:

• ekkrine or merocrine but rather an aqueous secretion without or with only minimal cell loss by exocytosis. Most of the sweat glands are ekkrin.
• Apocrine The secretion together with the apical part of the cell are transmitted through apocytose. This means that the tip of the cell is constricted as a vesicle. Together with the secretion, a part of the cell plasma and the cell membrane is thus also emitted. Apokrin are e.g. the scented glands in the skin (e.g. in the armpits), the mammary glands and the earache glands.
• For holocrins The entire cell is based on glands and releases the content. New cells are constantly moving from below. Holokrin are, for example, sebaceous glands.