1. Calcification without matrix vesicle formation is seen in ? compact bone , circumpulpal dentin & pathological hard tissues.
2. Heterogeneous calcification refers to – formation of collagen based calcified tissues.
3. Enamel has no matrix vesicles and no collagen hence no appositional growth possible, it is only crystal growth.
4. Pyrophosphates and non collagenous proteins inhibit OH apatite crystal growth.
5. Morphogenesis of fetus happens at – 4 to 8 weeks of gestation
6. The growth factor produced by one cell when influences other cell it is termed as – paracrine regulation (influencing self is autocrine regulation)
7. The change of bilaminar germ disc to trilaminar germ disc which happens at 3rd week of intra uterine life is termed as gastrulation
8. Urogenital system develops from – intermediate plate mesoderm
9. Adrenal medulla develops from neural crest and adrenal cortex from lateral plate mesoderm
10. Neural crest name is derived because – when these cells were identified in avian embryo they were found to differentiate at the crest of the neural fold hence the name. but in humans the same cells differentiate at the lateral aspect of neural plate.
11. Enzyme related to degree of keratinisation – acid phosphatase (also present in lysosomes, osteoclasts,odontoclasts- pink tooth,ameloblasts)
12. Enzyme related to taste discrimination – esterase
13. Enzyme increased in gingival hyperplasia- aminopeptidase activity
14. Enzyme helpful to differentiate blood capillaries and lymph capillaries – 5’nucleotidase activity (present only in lymph capillaries)
15. Invasion marker – laminin5
16. Alkaline phosphatase involved in – osteogenesis,dentinogenesis,cytochemical marker to differentiate preosteoblasts and osteoblasts,highest activity in hypertrophic zone of cartilage, high activity noted stratum intermedium of tooth development. Please don forget Paget’s disease in oral path. Absent in ameloblasts and calicified bone.
17. Cell membrane of ruffled ameloblasts – ATPase
18. Enzyme present in both osteoblasts and osteoclasts – cytochrome oxidase (citric acid cycle is also prominent in both the cells)
19. For studying ground substance – PAS method
20. Versican – present in lacunae of osteocyte/cementocyte
21. MPS present in pulp – hyaluronan & chondriotin sulphate
22. Amino acid grouping in teeth and bone done by- DNFB method & ninhydrin Schiff method
23. Type of collagen in osteoid – type X
24. The protein present in between the gaps of collagen fibrils which helps in ordered deposition of OH apatite crystals – phosphophoryn
25. Enamel rod sheath and odontoblastic process is lipidic in nature
26. Best fixative for enzymes and proteins – 10%Formaldehyde ph 7.0 neutral 0-4 degree Celsius
27. Best fixative for electron microscopy (EM)- glutaraldehyde (ideal for disinfecting all scopes… micro)
28. Rossmann’s fluid(for all with GLY) – formaldehyde ,alcohol,picric acid,acetic acid- to study glycoproteins,glycogen,proteoglycans
29. Carnoy’s mixture – ACE- acetic acid,chloroform,ethanol-to study nucleic acids (but historically in chemical cauterization of OKC also)
30. Visualizing DNA – fuelgen’s reaction
31. Post fixation done for lipid rich tissues and freeze dried specimens- using osmium tetra chloride
32. Study of lipids- para formaldehyde fixation
33. To study enzyme systems – cryostat or frozen section
34. Excellent 3 dimensional images of cell membrane – freeze fracture and freeze etching using EM
35. Common histological section thickness for un decalcified tissues – 10-15 microns
36. Latest technique for identifying of genes on tissue transplant – insitu hybridization
37. Both Qualitative and quantitative analysis of inorganic composition of calcified tissues -LASER spectroscopy (note for arthritis,implant placement the qualitative test done is DEXA SCAN)
38. Highly sulfated GAG glycosamino glycan is heparin
39. Hyaluronic acid is unsulfated ,high in loose connective tissues,helps in diffusion of substances (metabolic and pathological enzymes-eg cellulitis) called as ‘Spreading factor’of Duran Reynalds.
40. The supportive nature and plastic texture of cartilage is due to – chondriontin sulphate (cartilage has type II collagen)
41. Non aggregating proteoglycans – decorin,fibromodullin,perlecan,agrin&syndecan.
42. Glycoproteins are – fibronectin,laminin, osteonectin,tenascin & thrombospondin
43. Glycoprotein highly restricted to embryo – tenascin (re expression of tenascin in adult is associated with wound healing, nerve regeneration, tumorigenesis,metastasis)
44. Fibroblasts – formative and destructive cells of collagen
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