Types of epithelia. Glandular epithelium Dr. Károly Altdorfer

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Dr. Nemeskéri: Histology manual (not ready yet)

Dr. Nemeskéri: Histology (not ready yet)

Basic tissues

Organs (stomach, eyeball)  Tissues (epithelia, …)  Cells

Hematoxylin-eosin (H-E) Stainings: Most common: Hematoxylin-eosin (H-E) Blue (basophil) Red (acidophil, eosinophil)

Epithelial tissue is composed of tightly packed cells. Types of epithelia Covering epithelia Glandular epithelia Pigment epithelia Sensory epithelia (Myoepithelium)

Covering epithelia Glandular epithelia Pigment epithelia Sensory epithelia (Myoepithelium) Epithelial tissue Functions of epithelial cells: -protection of the internal environment (mechanical+biological) -resorption, excretion of materials -secretion -sensory function -(contraction)

1. Covering epithelia 1. Cells are closely packed 2. junctional complexes beetween the cells 3. covers or lines all internal and external body surfaces 4. basement membrane separates it from the underlying tissues Basal membrane = basal lamina + fibroreticular lamina (Light microscope electrone microscope)

Types of covering epithelium 1. simple epithelia  2. stratified epithelia:

2. Glandular epithelium EPITHELIAL SPECIALISATION FOR SECRETION MICROSCOPIC, PART OF AN ORGAN OR AN ORGAN BY ITSELF CONNECTIVE TISSUE FRAMEWORK

GLANDULAR EPITHELIA Exocrine glands Endocrine glands Secrete through ducts onto the surface of the gland Endocrine glands Release hormones into surrounding fluid (blood flow) A PATCH OF EPITHELIAL CELLS (INTERNAL SURFACE) OR A DOWNGROWTH THAT PROLIFERATES (EXTERNAL SURFACE)

MORPHOLOGICAL TYPES MULTICELLULAR UNICELLULAR Organs containing glandular epithelium (large glands, crypts) UNICELLULAR Individual secretory cells (goblet cells) TUBULO- ACINAR TUBULO- ALVEOLAR TUBULAR ALVEOLAR SIMPLE BRANCHING COMPOUND

CLASSIFICATION ACCORDING TO SECRETIONAL TYPES merokrine apokrine holokrine

CLASSIFICATION ACCORDING TO SECRETIONAL TYPES Merocrine (product released through exocytosis) Cells of the gland are unaltered Ex: Eccrine sweat glands, salivary glands Apocrine (involves the loss of both product and cytoplasm) Ex: Mammary gland, (prostate), scent glands Holocrine (destroys the whole cell) Ex: Sebaceous glands

MECHANISMS OF GLANDULAR SECRETION

SEROUS AND MUCOUS ACINI Merokrine secretion: SEROUS AND MUCOUS ACINI THE CELL'S PRODUCT SEROUS, LIKE SERUM - CLEAR, WATERY SOLUTION OF ENZYMES MUCOUS, LIKE MUCUS - GLYCOPROTEIN MIXTURE MIXED glands (most salivary glands) contain both types of cells (many serous demilunes) SEROUS glands (e.g., parotid gland or pancreas) MUCOUS glands (e.g., Brunner's glands)

Merokrine secretion SEROUS SECRETORY CELLS TYPICAL ACINUS (UNIT) TUBULOALVEOLAR small lumen round nuclei basophil cytoplasm THE CYTOPLASM IS POLARIZED BASAL CYTOPLASM – basophilic due to protein synthetic organelles (ribosomes on rough endoplasmic reticulum) APICAL CYTOPLASM - variously-staining secretory vesicles (zymogen granules) The Golgi apparatus is usually located midway along the cell, typically in a supranuclear position.

SEROUS SECRETORY CELLS TYPICAL ACINUS (UNIT) in a sweat gland COILED TUBULAR wide lumen round nuclei well stained cytoplasm THE CYTOPLASM IS POLARIZED Long excretory portion Opens onto the external surface

MUCOUS SECRETORY CELLS Merokrine secretion: MUCOUS SECRETORY CELLS TYPICAL ACINUS (UNIT) wide lumen flat nuclei poorly stained cytoplasm (foamy appearance) THE CYTOPLASM IS POLARIZED MUCOUS CELLS - "empty" appearance BASAL CYTOPLASM – nucleus and rest of cell organelles MIDDLE and APICAL CYTOPLASM – large secretory granules Mucus does not stain well with standard dyes, but is demonstrated with the Periodic Acid Shiff procedure (PAS stain).

UNICELLULAR (MUCOUS) GLAND GOBLET CELLS : scattered among enterocytes within the epithelium of the small intestine and colon, respiratory and reproductive tracts.  They secrete MUCUS, which facilitates passage of material.   The proportion of goblet cells to absorptive cells increases along the entire length of the bowel, with relatively few in the duodenum and very many in the colon.  

APOCRINE SECRETION 1. MAMMARY GLAND PROSTATE NON-LACTATING TYPICAL ACINUS (UNIT) wide lumen oval nuclei light staining in cytoplasm MAMMARY GLAND NON-LACTATING THE CYTOPLASM IS POLARIZED APOCRINE CELLS - irregular height (torn luminal surface) BASAL CYTOPLASM – nucleus + cell organelles MIDDLE and APICAL CYTOPLASM – large secretory granules (extreme exocytotic procedure- the upper part maybe missing) PROSTATE PSEUDO-APOCRINE LACTATING

APOCRINE SECRETION 2. APOCRINE SWEAT GLANDS open into hair follicles FOUND: axillae, perineum, and areolae mammae (phylogenetic remnant of the mammalian sexual scent gland; the sweat is initially odorless upon production. It is only after skin's bacteria has acted upon the apocrine sweat that it develops an odor)

HOLOCRINE SECRETION THE CYTOPLASM IS NOT POLARIZED TYPICAL ACINUS (UNIT) no lumen round nuclei light / no staining in cytoplasm THE CYTOPLASM IS NOT POLARIZED HOLOCRINE CELLS - gradually age and die cells with lipid-filled vacuoles short duct empties into hair follicle Associated with hair follicles in hair covered areas Independent of hair follicles at mucosal margins (lips, eyelids, penis, labia minora, nipples) Secretes oily substance (sebum) onto hair to waterproof hair and skin

STRUCTURES AIDING SECRETION MYOEPITHELIAL MUSCLE BUNDLES MYOEPITHELIAL CELLS ACTIN STAINING