Histology Flashcards
Histologically, what do giant cell tumours consist of?
Multi-nucleate giant cells.
Histologically what do giant cell tumours of the tendon sheath look like?
Multinucleated giant cells and haemosiderin.
Macroscopically what do giant cell tumours of the tendon sheath look like?
Pigmented lesion.
What doe skeletal muscle look like histologically?
Striated.
Unbranched.
Multinucleate (forms a syncytium).
Long cylindrical fibres.
Nuclei at the periphery of the fibre, just under the cell membrane (sarcolemma).
What is a fascicle?
Muscle fibre are grouped into bundles called fascicles.
What is the epimysium?
The connective tissue that surrounds the muscle as a whole.
What is a perimysium?
The connective tissue that surrounds a single fascicle.
What is an endomysium?
The connective tissue around a single muscle fibre.
What is a sarcomere?
Unit of contraction of the muscle cell.
What is a myofibril?
Thousands of sarcomeres placed end-to-end to form a myofibril.
What does a motor unit consist of?
One motor neuron and all the muscle fibres it innervates.
What is type I skeletal muscle?
Slow contracting fibres.
Oxidative metabolism.
Many mitochondria and myoglobin.
Resistant to fatigue.
Produce relatively less force.
‘Red’ fibres.
What is type IIa skeletal muscle?
Intermediate speed in contracting.
Reasonably resistant to fatigue.
Relatively uncommon fibres.
What is type IIb skeletal muscle?
Fast contracting fibres.
Anaerobic metabolism.
Few mitochondria and less myoglobin than type I.
Fatigue relatively easily and produce relatively greater force.
‘White’ fibres.
What is cartilage?
Semi-rigid and deformable.
Permeable.
Avascular.
Cells nourished by diffusion through the extracellular matrix.
What is bone?
Rigid.
Not permeable.
Cells within the bone must be nourished by blood vessels that pervade the tissue?
What are chondrocytes?
Cells found in cartilage that live within a space in the EC matrix called a lacuna. Secrete and maintain the extracellular matrix surrounding them.
Chondroblasts are immature chondrocytes.
What is type 2 collagen?
Fine and forms a 3D meshwork.
What is type 1 collagen?
Thicker than type I and aggregates into linear bundles.
What is hyaline cartilage?
Blue-white in colour, translucent and most common form of cartilage.
What is elastic cartilage?
Light yellow in colour and flexible due to elastic fibres.
What is fibrocartilage?
Hybrid between tendon and hyaline cartilage.
Densely packed bands of type I collagen interleaved with rows of chondrocytes, surrounded by small amounts of cartilaginous ECM.
Appears white.
Where can you find hyaline cartilage?
Articular surfaces.
Tracheal rings.
Costal cartilage.
Epiphyseal growth plates.
Precursor in foetus to many bones.
What is the function of bone?
Support.
Levers for effective movement.
Protection of internal organs.
Calcium store (>95% of total calcium in body is in the bone).
Haemopoiesis (blood cell production).
What is bone composed of?
65% bioapatite (a form of calcium phosphate - mostly hydroxyapatite).
23% collagen.
10% water.
2%non-collagen proteins.
What are the 2 types of bone?
Cortical bone.
Cancellous or trabecular bone.
What is cortical bone?
An outer shell of dense bone that makes up the shaft (diaphysis).
What is cancellous or trabecular bone?
Found at the ends of the bone (epiphyses).
Fine meshwork of bone.
What is the difference between compact and trabecular bone?
Bone cells and matrix are similar in compact and trabecular bone.
Both types are lamellar.
Marrow cavities (spaces) are found adjacent to trabecular bone.
What is an osteon?
Functional unit of compact bone.
What are osteocytes?
A bone cell trapped within bone.
What are osteoprogenitor cells?
Located on bone surfaces, e.g. under the periosteum, these cells serve as a pool of reserve osteoblasts.
What are osteoblasts?
Bone forming cells found on the surface of developing bone.
Have plentiful rough endoplasmic reticulum and prominent mitochondria.
What are osteoclasts?
Large multinucleated cells found on the surface of bone and are responsible for bone resorption.
What is bone remodelling?
Osteoclasts congregate and begin to ‘drill’ into the bone forming a tunnel.
A blood vessel grows into the tunnel bringing with it osteoblasts which line the tunnel and begin laying down new lamellar bone.
Process continues until only the space of a Haversian canal remains.
What is a basic multicellular unit?
The collection of osteoclasts and osteoblasts that participate in bone remodelling.
What is a Haversian canal?
Small canals which form a network in bone and contain blood vessels.
What is osteoid?
The osteoblasts that secrete collagen along with glycosaminoglycans, proteoglycans and other organic components of the bone matrix.
What is bone mineralisation?
Osteoid is the progenitor material that becomes hardened as it attracts calcium phosphate.
Thus osteoblasts don’t secrete bone directly by indirectly.
