WBR1012

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Author [[PageAuthor::Rim Halaby, M.D. [1]]]
Exam Type ExamType::USMLE Step 1
Main Category MainCategory::Embryology
Sub Category SubCategory::Hematology
Prompt [[Prompt::The levels of the different types of hematopoietic stem cells were measured in different organs extracted from aborted fetuses. Shown below is an image depicting hematopoiesis in different organs throughout fetal life and adulthood. Which of the following most likely represents hematopoiesis in the liver?

]]

Answer A AnswerA::A
Answer A Explanation [[AnswerAExp::The diagram in A depicts erythropiesis in the bone marrow which starts in the fetus at 18 weeks and continues throughout adulthood.]]
Answer B AnswerB::B
Answer B Explanation [[AnswerBExp::The diagram in B depicts erythropoiesis in the spleen which approximately occurs between 10 weeks and 28 weeks of the fetal life.]]
Answer C AnswerC::C
Answer C Explanation [[AnswerCExp::The diagram in C depicts erythropoiesis in the liver which approximately starts in the fetus at 6 weeks and continues until birth.]]
Answer D AnswerD::D
Answer D Explanation [[AnswerDExp::The diagram in D depicts erythropoiesis in the yolk sac which approximately starts in the fetus at 3 weeks and continues until 8 weeks.]]
Answer E AnswerE::E
Answer E Explanation AnswerEExp::This diagram is not characteristic of hematopoiesis in any organ.
Right Answer RightAnswer::C
Explanation [[Explanation::The site of erythropoiesis varies according to the age of the fetus. Fetal erythropoiesis occur in the following:

Shown below is an image depicting erythropoiesis in the fetus and adults.

Fetal erythropoiesis
Educational Objective: Erythropoiesis in the liver approximately starts in the fetus at 6 weeks and continues until birth.
References: First Aid 2014 page 264]]

Approved Approved::No
Keyword WBRKeyword::Erythropoiesis, WBRKeyword::fetal erythropoiesis, WBRKeyword::Blood, WBRKeyword::Development, WBRKeyword::Fetus, WBRKeyword::Embryology
Linked Question Linked::
Order in Linked Questions LinkedOrder::