Forms of classical and alternative secretion. Cell polarity

Secretion Not visible in LM sections Visible in LM sections In constitutive secretory pathway secretory vesicles DO NOT accumulate eg. extracellular matrix Membrane replacement or exocytosis All 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

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

Cell polarity Mast cell - Non-polarized Goblet cell - polarized http://www.bu.edu/histology/p/22602ooa.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%20cell

Protein secreting cell Exocrine pancreatic acinar cell (multicellular gland, polarized cell) Basic Histology 7.ed. Polarized cytoplasmic basophilia

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

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

Biogenic amine and proteoglycan secreting cell Any of a group of naturally occurring, biologically active amines, such as norepinephrine, histamine, and serotonin, that act primarily as neurotransmitters and are capable of affecting mental functioning and of regulating blood pressure, body temperature, and other bodily processes. accumulation degranulation http://quizlet.com/20863897/microanatomy-flash-cards/

Steroid hormone secreting cell Features A lot of SER Lipid droplets Tubular mitochondria www.life.uiuc.edu/csb/213/PPT/26.ppt

Steroid hormone secreting cell www.life.uiuc.edu/csb/213/PPT/26.ppt http://www.visualphotos.com/image/1x8466313/tubules_of_endoplasmic_reticulum_tem

Alternative secretion

Alternative secretion - ions Ecrin: Sweat gland cells (CFTR: Cystic Fibrosis Transmembrane Conductance Regulator

Alternative secretion - proteins e.g. secretion of IL-1 Beta (pro-inflammatory cytokine) Pro-IL-1beta inflammasome Molecular interaction after the stimulus induces the release

Alternative secretion - vesicule e.g. different pathways of alpha-synuclein secretion Classical secretory pathway 2) Recycling early endosomes 3) Exosomal vesicules (derived from MVB) http://www.nature.com/cddis/journal/v3/n7/fig_tab/cddis201294f2.html http://www.nature.com/cddis/journal/v3/n7/fig_tab/cddis201294f2.html

Multiple mechanisms is engaged for the release of IL-1β within the same cell population Mechanism recruited may be dependent upon the strength of the inflammatory stimulus as perceived by the cell http://www.sciencedirect.com/science/article/pii/S1359610111000475

Slides

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

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

Facultative

Name the organelles 1=? 2=? 3=? Z=? L=? 3 1 2 1: euchromatin 2: nucleus 3: RER Z: zymogen granules L: lumen http://visualhistology.com/Visual_Histology_Atlas/VHA_Chpt1_Cells.html 3 1 2 http://visualhistology.com/Visual_Histology_Atlas/VHA_Chpt1_Cells.html

Secretion or exocytosis or exocytosis All cells, continuously signal 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)