WBR1000

Author	[[PageAuthor::Rim Halaby, M.D. [1]]]
Exam Type	ExamType::USMLE Step 1
Main Category	MainCategory::Histology
Sub Category	SubCategory::Endocrine
Prompt	[[Prompt::A scientist investigating a novel antidiabetic drug injects rats with insulin antibodies to induce experimental diabetes. Shown below is an image depicting the localization of the insulin antibodies by immunofluorescent microscopy. The red color represents the insulin antibodies, the blue color represents the nuclei and the green color represents unspecific anti-mouse secondary antibody staining mostly the intercellular matrix. To which of the following cells does the area in red most likely correspond to? ]]
Answer A	AnswerA::Alpha cella
Answer A Explanation	[[AnswerAExp::Alpha cells produce glucagon. Alpha cells form 15–20% of the total number of cells of the islets of langerhans.]]
Answer B	AnswerB::Beta cells
Answer B Explanation	[[AnswerBExp::Beta cells produce insulin and amylin. Beta cells form 65–80% of the total number of cells of the islets of langerhans.]]
Answer C	AnswerC::Delta cells
Answer C Explanation	[[AnswerCExp::Delta cells produce somatostatin. Delta cells form 3–10% of the total number of cells of the islets of langerhans.]]
Answer D	AnswerD::Gamma cells
Answer D Explanation	[[AnswerDExp::Gamma cells, or PP cells, produce pancreatic polypeptide. Gamma cells form 3–5% of the total number of cells of the islets of langerhans.]]
Answer E	AnswerE::Epsilon cells
Answer E Explanation	[[AnswerEExp::Epsilon cells produce ghrelin. Epsilon cells form <1% of the total number of cells of the islets of langerhans.]]
Right Answer	RightAnswer::B
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 red. 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. Reference: First aid for USMLE step 1, (2013). Page 287. Educational Objective: References: ]]
Approved	Approved::No
Keyword	WBRKeyword::Beta cells, WBRKeyword::insulin
Linked Question	Linked::
Order in Linked Questions	LinkedOrder::