عملي Oral

Glands

M.Sc Sarah Ahmed
د . سارة (م 2)

Introduction

A gland is an organ that consists of specialized secretory cells. Secreted material is usually a liquid. Epithelial in origin. Present in singly or in groups. Unicellular or Multicellular 2 types: Exocrine Endocrine

Unicellular glands

Single cell like goblet cells


Exocrine: pour their secretions onto an epithelial surface, secrete their products through a duct onto an outer surface of the body
Endocrine (ductless): secrete their secretions directly into the blood.

Classification of exocrine glands

Based on shape & branching pattern of duct Based on mode of release of their product Based on the nature of their secretion

Classification based on shape & branching pattern of duct

Based on shape of secretory units (tubular or alveolar) & branching pattern of ducts. 2 types: Simple Compound

Contd… Simple glands: Simple tubular Simple coiled tubular Simple branched tubular Simple branched alveolar

Compound glands: Compound tubular Compound alveolar Compound tubulo- alveolar

Simple glands

Compound glands

Classification based on mode of secretion
Merocrine: (salivary gland, tear gland). Apocrine: (mammary gland). Holocrine: (sebaceous glands).

Modes of secretion Merocrine

Modes of secretion Merocrine: secretion by exocytosis


Modes of secretion Merocrine: secretion by exocytosis Apocrine


Modes of secretion Merocrine: secretion by exocytosis Apocrine: secretion by loss of cytoplasm


Modes of secretion Merocrine: secretion by exocytosis Apocrine: secretion by loss of cytoplasm Holocrine


Modes of secretion Merocrine: secretion by exocytosis Apocrine: secretion by loss of cytoplasm Holocrine: secretion through loss of entire cell

Classification based on the nature of secretion

Serous glands Mucous glands Mixed glands

Serous glands

Secretion: thin, watery, rich in enzymes, protein in nature. Cytoplasm: granular (stain darkly from pink to dark purple with H/E stain) & rich in rER. Nuclei: rounded & basally placed. Ex:sweat gland

Mucous glands

Secretion: contains mucopolysaccharides which collects in the apical part of cell. Cytoplasm: stain very lightly with H/E stain & therefore gives empty look. Nuclei: basally placed & flattened (mucoid pushes the nuclei). Ex:goblet cell

Mixed glands

Contain both serous & mucous secretory units. Sometimes serous cells form crescent caps on mucous acini called as serous demilunes. Ex: sublingual gland Mandibular gland