Practical Histology Section - Non-membranous Organelles and Inclusions PDF

Practical Histology Section Non-membranous organelles and inclusions  Learning Objectives Enumerate non-membranous organelles. Identify histological structure of ribosomes at LM and EM levels. Describe histological structure of microtubules at EM level. Identify histological st...

Practical Histology Section Non-membranous organelles and inclusions  Learning Objectives Enumerate non-membranous organelles. Identify histological structure of ribosomes at LM and EM levels. Describe histological structure of microtubules at EM level. Identify histological structure of centriole at EM level. Describe histological structure of cilia at LM and EM levels. Identify histological structure of Microvilli at LM and EM level. Identify different types of inclusions.  Non-membranous organelles Ribosomes Microtubules Centrioles Cilia and flagella Cell Filaments.  RIBOSOMES small particles, nonmembranous dynamic organelles, present either free or attached to rER. L/M:- basophilia of the cytoplasm which may be: a) Diffuse basophilia. b) Localized basophilia E/M:- Electron-dense granules either free in cytoplasm or attached to rER. TEM of attached ribosomes Electron dense granule. Polyribosomes: Electron dense granules attached together by thin electron dense Filament of mRNA forming whorl's figures. MICROTUBULES Def: Microtubules are non- membranous organelles. Site: In all cells especially where stiffness, shape or oriented motion are needed as in blood platelets, cilia, flagella, mitotic spindle,…….  MICROTUBULES L/M:- Appear as filaments after using immunofluorescent staining technique examined by fluorescent microscope. E/M: Long, straight, cylindrical, non- branching structures, (L.S).  Its wall is formed of 13 protofilaments (T.S). Diameter constant  Longtudinal section (L.S) of MT Transverse section (T.S) of MT EM: in L/S; appear as long, slender, non branched EM: in T/S; appear as small circles, formed of 13 tubules of uniform diameter and variable length protofilaments MICROTUBULES Functions 1- Cytoskeleton of the cell 2- Formation of mitotic spindle Mitotic spindle 3- Formation of centrioles & the axoneme of cilia & flagella. 4- Movement of organelles and vesicles in the cytoplasm. cytoskeleton  CENTRIOLE Def: Non- membranous organoid. Site: Present close to the nucleus & Golgi apparatus in all cells except those that do not divide as RBCs & nerve cells.  CENTERIOLE Non- Membranous organelle [ E/M  Appears as a short cylinder. The wall is composed of 9 triplets of microtubules.  The triplet microtubules are formed of 3 microtubules(a,b and c).  Microtubule a is formed of 13 protofilaments while b& c are formed of 10 protofilaments.  TEM of CENTRIOLE TEM: The wall is formed of 27 microtubules arranged as 9 triplets with no central microtubules.  CILIA Def: elongated motile structures forming outgrowths of the free cell surface. Site: present in the ciliated epithelium. L/M: - Short, fine hair-like processes arising from the free cell surface.  CILIA (basal body+shaft+rootlet+basal foot) E/M:  Appear as outgrowths of the cell which are covered with plasma membrane.  Each cilium is formed of: 1. Basal body: This is a centriole which has migrated to near the cell surface.  CILIA 2. Shaft ( axoneme ): formed of : 2 single (singlets) microtubules in the center and 9 paired (doublets) microtubules circularly arranged around the periphery. CILIA  CILIA 3. Rootlets: extend from the deep aspect of the basal body. 4. Basal foot: attached laterally to the basal body  TEM OF CILIA Basal body of cilia Shaft of cilia SEM OF CILIA  CILIA Functions: 1. Spreading of a thin film of fluid or mucus across a surface. 2. Become modified to receive stimuli as: light stimuli in rods & cones of the retina. NB. Flagella: Motile structures resemble cilia but are rather longer and usually single.  N.B: Cytoskeleton Cytoskeleton Formed of: 1- microtubules 2- microfilaments (actin) 3- intermediate filaments  CELL FILAMENTS According to the diameter , they are classified into 3 main types: Thick filaments: 10-15 nm as myosin filaments. Intermediate filaments: 8-10 nm as in neurofilaments. Thin filaments: 6-8nm as actin filaments.  Cell filaments Actin filaments forming sheets  Actin filaments forming Microvilli - Extensions from the apical cell membrane LM of Microvilli EM of Microvilli (LS and TS)  Cell inclusions  CELL INCLUSIONS Def: They are temporary constituents of the cell. They may be: - Nutritive substances: proteins (secretory granules), CHO (glycogen) & fats (lipid droplets). - Pigments: Endogenous (melanin, Hb, Hb derivatives as hemosiderin, lipofuscin) and exogenous (carbon, tattoo particles). - Crystalloids e.g. crystalloids that present in sertoli cells. Liver glycogen ( stained by Best's Carmine) TEM of glycogen granules - Structure: glycogen granules appear as rosette shape electron dense granules TEM of Secretory granules - Structure: electron dense granules of variable size surrounded by membrane Fat cells (Haematoxylin and eosin) showing singet ring appearance  Fat cells (Sudan III) Unilocular adipose connective tissue TEM of lipid droplets - Structure: Electron dense rounded with no limiting membrane  Group Discussion QUIZ 1. Identify this photomicrograph. 2. Mention the main function. 1.Identify the structure in the attached photomicrograph 2. Explain your answer 3. The circle encloses........... 1. Identify the structures in the attached photomicrograph 2. The red arrow points to.............. 3. The white arrow head points to................ 1. Identify the structure pointed to by arrow 2. Mention its main functions 1.Identify structures in the attached photomicrograph 2. Explain your answer 3. The circle encloses................ 4. The arrow points to................... 1. Identify this photomicrograph 2. What is the used stain?  REFERENCES Pawlina, W. (2016): A text of Atlas with cell and molecular biology. 7th ed. Lippincott, Williams and Wilkins.  Junqueira, L.C.; Carneiro, J. and Kelly, R.O.(2014): Basic Histology. 11th ed. Appleton and Lange. New York. Gartener, L.P. and Haiat, J.L. (2011): C.V.S. In: Colour Text Book of Histology, 4th ed. Saunders Elsevier.