WBR1005

Author	[[PageAuthor::Rim Halaby, M.D. [1]]]
Exam Type	ExamType::USMLE Step 1
Main Category	MainCategory::Histology
Sub Category	SubCategory::Endocrine
Prompt	[[Prompt::Shown below is an image depicting the light microscopy of a paraffin embedded mouse islet. The green and red colors stain two hormones secreted by the pancreas while the blue color represents the nuclei of the cells. Which of the following types of pancreatic cells most likely correspond the the green and red colors respectively? ]]
Answer A	AnswerA::Delta cells and alpha cells
Answer A Explanation	[[AnswerAExp::Delta cells produce somatostatin and alpha cells produce glucagon. Since insulin is produced in the beta cells, the insulin antibodies will label the beta cells in green. In addition, since glucagon is secreted by the alpha cells, the glucagon antibodies will label these cells in red.]]
Answer B	AnswerB::Delta cells and beta cells
Answer B Explanation	[[AnswerBExp::Delta cells produce somatostatin and beta cells produce insulin. Since insulin is produced in the beta cells, the insulin antibodies will label the beta cells in green. In addition, since glucagon is secreted by the alpha cells, the glucagon antibodies will label these cells in red.]]
Answer C	AnswerC::Beta cells and delta cells
Answer C Explanation	[[AnswerCExp::Beta cells produce insulin and delta cells produce somatostatin. Since insulin is produced in the beta cells, the insulin antibodies will label the beta cells in green. In addition, since glucagon is secreted by the alpha cells, the glucagon antibodies will label these cells in red.]]
Answer D	AnswerD::Beta cells and alpha cells
Answer D Explanation	[[AnswerDExp::Beta cells produce insulin and alpha cells produce glucagon. Since insulin is produced in the beta cells, the insulin antibodies will label the beta cells in green. In addition, since glucagon is secreted by the alpha cells, the glucagon antibodies will label these cells in red.]]
Answer E	AnswerE::Alpha cells and beta cells
Answer E Explanation	[[AnswerEExp::Alpha cells produce glucagon and beta cells produce insulin. Since insulin is produced in the beta cells, the insulin antibodies will label the beta cells in green. In addition, since glucagon is secreted by the alpha cells, the glucagon antibodies will label these cells in red.]]
Right Answer	RightAnswer::D
Explanation	[[Explanation::Hormones produced in the islets of Langerhans are secreted directly into the blood flow by (at least) five types of cells. In rat islets, endocrine cell subsets are distributed as follows: - Alpha cells producing glucagon (15–20% of total islet cells) - Beta cells producing insulin and amylin (65–80%)- Delta cells producing somatostatin (3–10%) - Gamma cells or PP cells producing pancreatic polypeptide (3–5%) - Epsilon cells producing ghrelin (<1%) Since insulin is produced in the beta cells, the insulin antibodies will label the beta cells in green. In addition, since glucagon is secreted by the alpha cells, the glucagon antibodies will label these cells in red. In addition, note that the beta cells occupy most of the center of the islets of Langerhans while the alpha cells occupy the periphery. Educational objective: The islets of langerhans are formed by different types of cells. Beta cells occupy the center of the islet of langerhans and produce insulin, while alpha cells are located in the periphery and produce glucagon. Reference: First aid for USMLE step 1, (2013). Page 287. Educational Objective: References: ]]
Approved	Approved::No
Keyword	WBRKeyword::Insulin, WBRKeyword::glucagon, WBRKeyword::beta cells
Linked Question	Linked::
Order in Linked Questions	LinkedOrder::