WBR1012
| 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. If the hematopoetic stem cells were measured in the liver of fetuses aborted at different gestational age, 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.
Educational objective: Erythropoiesis in the liver approximately starts in the fetus at 6 weeks and continues until birth. Reference:
First aid for USMLE step 1, 2014. Page 264. |
| Approved | Approved::No |
| Keyword | WBRKeyword::Erythropoiesis, WBRKeyword::fetal erythropoiesis |
| Linked Question | Linked:: |
| Order in Linked Questions | LinkedOrder:: |
