518. Which of the following cell types show abnormal function when there is a history in a young adult of multiple arm and leg fractures following minor falls, with a slight weakness of facial muscles on the left, mild anemia, and with generalized bony widening with partial obliteration of marrow spaces?

 A.  Granulocytic stem cells 
 B.  Megakaryocytes 
 C.  Plasma cells 
 D.  Osteoblasts 
 E.  Osteoclasts

517. A 5-year-old child has blue-tinged sclera, hearing loss, and small, slightly blue, misshapen teeth. Radiologic studies confirm the presence of numerous fractures of various ages. No significant degree of bruising is seen over sites of recent fracture. The disease this child most likely has is related to abnormal metabolism involving which of the following substances?

 A.  Collagen 
 B.  Glycogen 
 C.  Mucopolysaccharides 
 D. Purines 
 E.  Tyrosine 

516. An animal is made diabetic by injection of a drug that destroys pancreatic ß cells. Removal of which of the following organs would most likely produce a decrease in blood glucose concentration in this animal?

A.  Anterior pituitary   
B.  Colon   
C.  Gonads   
D.  Kidney   
E.  Pancreas