Secretory Vesiclesand Granulocytes, Fixation, Epithelia Flashcards
How to prepare tissues to study under light microscope
fixation: tissue immersed in stabilizing fixative solution that prevents degradation of tissue structure by enzymes eg formaldehyde
dehydration: tissue goes through a series of
increasingly concentrated alcohol solutions, ending in 100%, which removes all water
Clearing: alcohol removed after placing in organic solvent where both alcohol and paraffin miscible
Infiltration: placed in melted paraffin
Embedding: Allows tissue with paraffin to harden in a small container
A microtome is used to section the paraffin blocks
How does dyes stain tissues
by forming electrostatic linkages with ionizable radicles of macromolecules in tissues
basic dyes and acidic dyes
cell components with net negative charge eg DNA and RNA are basillophilic and stain well with basic dyes eg hematoxylin
cationic cell components like proteins or mitochonddria or collagen are acidophillic and stain well with acid dyes eg eoisin
What are secretory vesicles and what do they do?
vesicles from golgi
stores products until ready for exocytosis
Secretory vesicles mediate vesicular transport of cargo, e.g. hormones or
neurotransmitters
What 2 main groups can epithelia be divided into
covering and glandular
Types of simple epithelia
simple squamous: found in innermost lining of blood vessels (endothelium) also in mesothelium.
simple cuboidal: The covering epithelium found in ovary and exocrine glands. The secretory and absorptive epithelium found in proximal/distal convoluted tubules.
simple columnar: has absorptive, secretory, ciliated, sensory and covering functions. Found in stomach, small intestine etc
pseudostratified: found in respiratory tract HAS CILIA
what is a granulocyte
they are white blood cells with secretory granules in their cytoplasm
The 3 types of granulocytes
neutrophils
eoisinphils
basophils
feautures and functions of neutrophils
- 3-5 segmented nucleus
- azurophilic granules/lysosomes
- has specific secondary granules that stains light pink
- normally first leukocyte to arrive at sight of infection
- function: kill and phagocytose bacteria
- can live in anaerobic conditions
feautres and functions of eosinphils
- bean shaped 2 lobed nucleus with distinct bridge
- acidophillic granules reddish/pink
- slighlty larger than neutrophil
- role in the inflammatory response triggered by allergies (chemokines and cytokines)
- function: Kill helminthic and other parasites; modulate local inflammation
feaurtes and functions of basophils
- very rare in blood 0.5-2%
- 2 lobed nucleus
- basillophilic granules containing histamines that increase permeability of capillaries
- function: modulate inflammation, release histamine during
allergy
key features of granulocytes
*Spherical, although may become amoeboid
* Non-dividing, Golgi & RER are poorly developed
* Few mitochondria, glycolysis allows them to function in low oxygen regions
* Chemotaxis attracts them to other tissues
