WBR1000

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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 injects rats with insulin antibodies to induce experimental diabetes.

Shown below is an image depicting the localization of the insulin antibody by immunofluorescent microscopy. Shown in red are the insulin antibodies and shown in blue are green unspecific anti-mouse secondary antibody staining mostly the intercellular matrix. To which of the following cells does the area in red corresponds 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%)

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::