Secretion Secretion eg extracellular matrix Membrane replacement In

Secretion

Secretion eg. extracellular matrix Membrane replacement In constitutive secretory pathway or exocytosis secretory vesicles. All. DO NOT accumulate cells, continuously Not visible in LM sections signal In regulated secretory pathway secretory vesicles accumulate in glandular cells or exocytosis Hormone, digestive enzymes or neurotransmitter Visible in LM sections Glandular cells and neurons

Note the differences: • Secretion: synthesis, modification and release of different substances having physiological function • Excretion: Discharging waste matter • Common step: exocytosis: fusion of the membrane of a vesicle and the plasma membrane thus release of vesicle content outside of the cell 3

Grouping of glands According to the: Ø Size: unicellular - multicellular Ø Site where the substances are secreted to: exocrine – endocrine Ø Mechanism of release: merocrine, holocrine, apocrine Ø Cell polarity : polarized not polarized Ø Secreted substances : proteins highly glycosylated proteins biogenic amines proteoglycans steroids etc. 4

Cell polarity Mast cell - Non-polarized Goblet cell - polarized http: //www. bu. edu/histology/p/22602 ooa. htm http: //www. studyblue. com/notes/note/n/epithelium-and-glands/deck/12029883

Secreted substances

Protein secreting cell Plasma cell (unicellular) http: //www. gophoto. us/key/tem%20 cell

Protein secreting cell Exocrine pancreatic acinar cell (multicellular gland, polarized cell) Polarized cytoplasmic basophilia

Protein secreting cell Exocrine pancreatic acinar cell (multicellular gland, polarized cell) Condensation (Water loss)

Highly glycosylated protein = glycoprotein (mucus) secreting cell Hydration Goblet cell (unicellular, polarized) (water uptake) http: //www. studyblue. com/notes/note/n/epithelium-and-glands/deck/12029883

Biogenic amine and proteoglycan secreting cell accumulation http: //quizlet. com/20863897/microanatomy-flash-cards/ degranulation

Steroid hormone secreting cell Features – A lot of SER – Lipid droplets – Tubular mitochondria

Steroid hormone secreting cell http: //www. visualphotos. com/image/1 x 8466313/tubules_of_endoplasmic_reticulum_tem

Slide

Slide No. 11. Rat peritoneal fluid, thick-drop (toluidine blue) 1: mast cells: (metachromasia due to heparin content) Accumulation and degranulation accumulation 2: lymphocyte

Slide No. 11. Rat peritoneal fluid, thick-drop (toluidine blue) Mast cell during degranulation 1: nucleus of mast cell

Facultative

Secretion eg. extracellular matrix Membrane replacement or exocytosis All cells, continuously signal or exocytosis Hormone, digestive enzyme or neurotransmitter Glandular cells and neurons

Mechanism of release (types of glands) Merocrine E. g. exocrine part of pancreas Holocrine Eg. Sebaceous gland Apocrine E. g. Mammary gland Some sweat glands