GLANDULAR EPITHELIUM Dr Katalin Gallatz FUNCTION AND TYPES

GLANDULAR EPITHELIUM Dr. Katalin Gallatz

FUNCTION AND TYPES OF EPITHELIUM 3. Absorbtion 4. Excretion 5. Secretion GLANDULAR EPITHELIUM 6. Sensation SENSORY EPITHELIUM 7. Contractility MYOEPITHEL COVERING EPITHELIUM 1. Covering and protecting surfaces 2. Diffusion

Covering and protection – Covering epithelium 1. epithelial cells cover the external and internal surfaces, 2. protect underlying tissue from mechanical injury, harmful chemicals, invading bacteria and from excessive loss of water. Diffusion Simple squamous epithelium promotes the diffusion of gases, liquids and nutrients ( walls of capillaries and lungs).

Characteristics of covering epithelia 1. Cells of the epithelium are closely packed. 2. Junctional complexes can be found beetween the cells. 3. Small amount of intercellular substance 4. Cells form one or more layers. 5. Cover or line all internal and external body surfaces. 6. Basement membrane separates it from the underlying tissues

BASEMENT MEMBRANE COMPONENTS: I. Basal lamina a. lamina lucida b. lamina densa II. Reticular lamina

Types of covering epithelium Covering epithelium can be divided into two groups depending on the number of layers 1. simple epithelium is only one cell thick 2. stratified epithelium is two or more cells thick

Glandular Epithelium n n n Epithelial are cells specialized to produce secretion. Secretion – exocytotic release of products, Molecules to be secreted may be stored in membrane bound secretory granules

Glands are classified as : n ENDOCRINE and EXOCRINE depending on their route of secretion

Formation of the exocrine and endocrine glands

ENDOCRINE GLANDS n Secretory products called hormones, are secreted directly into the blood n n No ducts Large amount of capillaries

ENDOCRINE GLANDS

Follicular type (thyroid gland) adenohypophysis

EXOCRINE GLANDS n release their products onto the free surface of the skin or n mucouos membranes of tubular organs of the digestive, respiratory or reproductive tracts.

Exocrine glands the can be classified according to A) Number of cells Uni- or multicellular B) Mode of secretion holocrine, apocrine, merocrine D) Shape tubular, alveolar (acinar), tubuloalveolar C) Secretory products mucous and serous

Classification according to the number of the cells 1. Unicellular 2. Multicellular A. ) simple (one unbranched duct)- sweat gland B. ) compound (branched ducts) salivary glands, pancreas

Unicellular glands n They are scattered among other non-secretory epithelial cells n They have no ducts, but they secrete their products directly on the free surface n The most common unicellular exocrine glands are the goblet cells (mucus secreting cells)

Unicellular endoepithelial gland: goblet cell Narrow basal part: nucleus and RER Apical part: basophilic mucin containing secretory granules foamy apperence From Dr. Zita Puskár

Unicellular glands

trachea Goblet cells small intestine simple columnar epithelium with cuticule Pseudostratified columnar epithelium From Dr. Zita Puskár

Demonstration of mucins with different stainings small intestine H. E. pale small intestine PAS purple large intestine mucicarmin redish From Dr. Zita Puskár

EM picture of the goblet cell

Multicellular glands a) intraepithelial gland is entirely within the epithelium. b) extraepithelial gland below epithelium

Multicellular endoepithelial glands In the epithelium of the male urethra From Dr. Zita Puskár

Exocrine gland types according to their shape

Compound tubuloalveolar mixed gland submandibular gland

Modes of Secretion (how products leave the cell) 1) merocrine - secretion does not affect the well-being of the cell sweat glands, salivary glands, pancreas etc. 2) apocrine 3) holocrine - small part of the cell cytoplasm is lost with the secretion; mammary glands - great deal of cytoplasm is lost with the secretion; the cell dies. sebaceous glands

Modes of Secretion (how products leave the cell) merocrine apocrine -secretory granules are formed inside the cytoplasm, and leave the cell with exocytosis, pancreas, salivary glands, lacimal gland, sweat glands holocrine Apical part of the The whole cell cytoplasm with a part of degenerates, dies the cell-membrane and forms the leaves the surface secretum mammary gland sebaceaous glands

11. Holocrine secretion (sebaceous gland, hairy skin, H-E) The whole cell degenerates, dies and forms the secretum

HOLOCRINE SECRETION SEBACEAUOS GLAND

APOCRINE SECRETION mammary gland Apical part of the cytoplasm with a part of the cell-membrane leaves the surface

Merocrine secretion Secretory granules are formed inside the cytoplasm, and leave the cell with exocytosis

MEROCRINE SECRETION Sero-mucous gland (submandibular gland)

Composition of the secretum A) mucous B) serous C) sero-mucous D) lipid

Mucous gland - basally located nuclei - viscous secretory product - well-seen, wide lumen - pale-stained, foamy citoplasm with H. E. Esophagus

Salivary gland HE Serous glands - centrally located nucleus - basophil cytoplasm - narrow lumen - protein-reach fluidy secretum Exocrine pancreas HE

Serous (pancreatic acinar) cell

Mixed sero-mucous gland Gianuzzi’s demilune ducts M S

MEROCRINE SECRETION Sero-mucous gland submandibular gland

Sero-mucous gland

Parts of the duct-system A. Intercalated duct B. Salivary (striated) duct C. Interlobular duct D. Excretory duct A B

interlobular duct intercalated duct

Myoepithelium n n n Myoepithelium - specialized epithelial cells with powers of contraction, Surround glandular acini and ducts of many glands, Contain actin, myosin, cytotokeratin definitely epithelial in origin

Myoepithelial cell in salivary gland

Thank you for your attention!