Histopathology:part 2 Flashcards
Structure and features of woven bone
Features : Weak < Find in high turnover states
Structure : Disorganised and not in organised lamellar structure
Found in : developing sekeleton
Describe the staining of calcified and uncalcified bone in Masson-Trichrome stain.
Calcified – green Uncalcified – orange
Explain how we look at histological samples
Well in the majority of cases it will be simply by using H & E staining on decalcified samples. But there may be reasons to use more complex stains on calcified samples requiring histology labs that are specifically set up to perform them. These include Masson-Golder Trichrome staining to look at the amount of mineralised vs unmineralised bone. And tetracycline labelling to allow dynamic histomorphometry to measure the rates of bone formation and turnover
What is Paget’s disease?
Disorder of bone turnover (there is a lack of proper communication between the cells)
What are Howship’s Lacunae?
Pits in the bone surface where osteoclasts are found (also called resorption bays)
What are the two common outcomes of osteomalacia
In children the inability to properly mineralise bone results in rickets with the characteristic widening of the growth plate and bowing of the long bones shown in this x-ray.
Another common outcome is Looser’s zone fractrues. These are pseudo-fractures at locations of high tensile stress, normally at right angles to the cortex and extending only part way through the bone.
What are the primary causes of osteoporosis?
Age Post-menopause
What are the three main functions of bones?
Mechanical – support and site for muscle attachment, Protective(contains vital organs and bone marrow), Metabolic – reserve of calcium
What are the consequences of renal osteodystrophy to the blood and endocrine system.
Hyperphosphataemia ,Hypocalcaemia as a result of a decrease in vitamin D metabolism ,Secondary hyperparathyroidism ,Metabolic acidosis ,Aluminium deposition
What is renal osteodystrophy to the bone?
Increased bone resorption (osteitis fibrosa cystica) Osteomalacia Osteoporosis Osteosclerosis Growth retardation
What is osteomalacia and what can it be caused by?
Condition of defective bone mineralisation that can be caused by: Vitamin D deficiency, Phosphate deficiency (usually related to chronic renal disease).
In osteomalacia there is no sufficient available calcium (or as I mentioned in some cases Phosphate) to form the hydroxyapatite crystals necessary to mineralise bone.
Recall Common metabolic bone diseases
.•Osteoporosis
- Osteomalacia/Rickets
- Primary hyperparathyroidism
- Renal osteodystrophy
- Paget’s disease
Describe the histology of osteomalacia.
No calcification of bone More uncalcified osteoid Bones are very bendy and cannot carry musculature very easily
What is a Haversian canal?
Channel that blood vessels run in within bone
What does vitamin Ddo innormal physiology
Well Vitamin D plays an integral role in calcium metabolism. We get vitamin D from sunlight exposure and in our diets. Activated Vitamin D acts to increase Calcium absorbtion in the intestine and re-absorbtion in the kidneys so increasing serum calcium levels.
