Undifferentiated mesenchymal cells around blood vessels are known as:

# Undifferentiated mesenchymal cells around blood vessels are known as:

A. Histiocytes

B. Pericytes

C. Fibroblast

D. Osteoblast

The correct answer is B. Pericytes.

Experimental studies have shown that a population of progenitor cells with the potential to differentiate into several distinct mesenchymal cell types can be isolated from the periodontal ligament. In cell culture, periodontal ligament stem cells can differentiate into cells that form bone, cementum, cartilage, fat, muscle, and neuron- and glial-like cells. Recent work indicates that perivascular cells (pericytes) associated with the microvasculature of alveolar bone and periodontal ligament of mice can differentiate into osteoblasts, cementoblasts, cementocytes, and periodontal ligament fibroblasts in

untreated animals, as well as after injury of the periodontium.

Reference: Fundamentals of Oral Histology and Physiology, Arthur R. Hand, 2014, Page no 128

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The protein content of a keratocyst is found to be:

# The protein content of a keratocyst is found to be:

A. less than 4 gm/dL

B. 6 mg/dL

C. Equal to serum protein

D. More than serum protein

The correct answer is A. less than 4 gm/dL.

Aspirational biopsy of odontogenic keratocysts contains a greasy fluid which is pale in colour and contains keratotic squames. Protein content of cyst fluid below 4g% is diagnostic of odontogenic keratocysts. Smaller and unilocular lesions resembling other types of cysts may require a biopsy to confirm the diagnosis. On a CT scan, the radiodensity of a keratocystic odontogenic tumour is about 30 Hounsfield units, which is about the same as ameloblastomas. However, ameloblastomas show more bone expansion and seldom show high density areas.

Reference: Wikipedia

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Familial multilocular cystic disease of the jaws

 # Which of the following is also known as familial multilocular cystic disease of the jaws?

A. Osteopetrosis

B. Cleidocranial dysostosis

C. Hemifacial microsomia

D. Cherubism

The correct answer is D. Cherubism.

Cherubism, a non-neoplastic hereditary bone lesion that is histologically similar to central giant cell granuloma, affects the jaws of children bilaterally and symmetrically, usually producing the so-called cherubic look (Fig. 17-13). The disease was first described in 1933 by Jones, who called it familial multilocular disease of the jaws. The term ‘cherubism’, was introduced by Jones and others to describe the clinical appearance of affected patients. According to the WHO classification, cherubism belongs to a group of non-neoplastic bone lesions affecting only the jaws. It is a rare, benign condition with autosomal dominant inheritance, and it is one of the very few genetically determined osteoclastic lesions in the human body. It appears to have 100% penetrance in males and only 50–70% penetrance in females. There is great variation in the clinical expression.

Reference: Shafer’s Textbook of ORAL PATHOLOGY, 7th Edition, Page No: 715

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Cause of osteogenesis imperfecta is:

# Cause of osteogenesis imperfecta is:

A. Defect in type I collagen

B. Defect in type II collagen

C. Defect in maturation process

D. Defect in calcification process

The correct answer is A. Defect in type I collagen.

Osteogenesis imperfecta (OI) is a serious disease, the molecular pathogenesis of which is being elucidated and it bears a superficial relatedness to dentinogenesis imperfecta, a milder condition affecting mesodermal tissues. It is a condition resulting from abnormality in the type I collagen, which most commonly manifests as fragility of bones. Although osteogenesis imperfecta is generally recognized as representing a hereditary autosomal dominant characteristic, autosomal recessive and nonhereditary types also occur.

Reference: Shafer’s Textbook of ORAL PATHOLOGY, 7th Edition, Page No: 699

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