EXOCRINE GLANDS:
Exocrine Glands Classification:
- Classification based on the shape of the secretory portion/duct:
Simple: Having an unbranched duct.
Simple tubular: Tubular-shaped secretory portion.
Straight simple: Intestinal glands (Crypts of Lieberkühn).
Coiled: Sweat glands.
Branched: Found in the stomach and endometrium of the uterus.
Simple acinar: Sac-like secretory portion.
Unbranched acinar: Found in the penile part of male urethral glands.
Branched acinar: Sebaceous glands.
Compound: Having a duct network.
Tubular: Brunner glands of the duodenum.
Acinar: Parotid gland, pancreas, mammary gland.
Tubulo-acinar: Salivary gland, submandibular gland, sublingual gland.
- Classification based on the nature of the secretory product:
Mucous glands: Produce mucus, like pyloric glands of the stomach.
Serous glands: Produce serous watery secretions, like the salivary gland.
Mixed glands: Produce both mucous and serous secretions, like the sublingual and submandibular glands.
- Classification based on the mode of secretion:
Merocrine: Secretory product is discharged without loss of cell cytoplasm (e.g., salivary, lacrimal, intestinal glands), also called eccrine glands.
Apocrine: Some part of cell cytoplasm is lost with secretory products (e.g., sweat glands of the axilla, ceruminous glands of the ear).
Holocrine: The entire cell is lost with secretion (e.g., sebaceous glands).
Acne Vulgaris (Histological Basics):
Acne vulgaris is a skin disorder characterized by comedones (blackheads and whiteheads), papules, pustules, nodules, and in severe cases, cysts. The cause is abnormal keratinization of the follicles, leading to the formation of a plug called a microcomedo, which enlarges into a comedo.