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{{WBRQuestion
{{WBRQuestion
|QuestionAuthor={{Rim}}
|QuestionAuthor= {{Rim}} (Reviewed by  {{YD}})
|ExamType=USMLE Step 1
|ExamType=USMLE Step 1
|MainCategory=Embryology
|MainCategory=Embryology
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|MainCategory=Embryology
|MainCategory=Embryology
|SubCategory=Hematology
|SubCategory=Hematology
|MainCategory=Embryology
|MainCategory=Embryology
|MainCategory=Embryology
|MainCategory=Embryology
|MainCategory=Embryology
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|MainCategory=Embryology
|MainCategory=Embryology
|SubCategory=Hematology
|SubCategory=Hematology
|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 ages, which of the following most likely represents hematopoiesis in the liver?
|Prompt=The concentrations of different types of hematopoietic stem cells are measured in various organs extracted from aborted fetuses.  Shown below is an image that depicts hematopoiesis in various organs throughout fetal life and adulthood. Which of the following most likely represents hematopoiesis in the liver?


[[ File:Fetal erythropiesis question.png]]
[[ File:Fetal erythropiesis question.png]]
|Explanation=The site of erythropoiesis varies according to the age of the fetus. Fetal erythropoiesis occur in the following:
|Explanation=The site of erythropoiesis varies according to the age of the fetus. Fetal erythropoiesis occur in the following organs:<br>
* [[Yolk sac]]: 3 weeks - 8 weeks
* [[Yolk sac]]: 3 weeks - 8 weeks<br>
* [[Liver]]: 6 weeks - birth
* [[Liver]]: 6 weeks - birth<br>
* [[Spleen]]: 10 weeks - 28 weeks
* [[Spleen]]: 10 weeks - 28 weeks<br>
* [[Bone marrow]]: 18 weeks - adulthood
* [[Bone marrow]]: 18 weeks - adulthood<br>
 
<br>
Shown below is an image depicting erythropoiesis in the fetus and adults.
Shown below is an image that depicts erythropoiesis in fetuses and adults.<br>
 
[[File:Fetal erythropoiesis.png|Fetal erythropoiesis]]
[[File:Fetal erythropoiesis.png|Fetal erythropoiesis]]
'''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.
|AnswerA=A
|AnswerA=A
|AnswerAExp=The diagram in A depicts [[erythropiesis]] in the [[bone marrow]] which starts in the fetus at 18 weeks and continues throughout adulthood.
|AnswerAExp=Option A depicts [[erythropiesis]] in the [[bone marrow]], which typically starts at 18 weeks gestation and continues throughout adulthood.
|AnswerB=B
|AnswerB=B
|AnswerBExp=The diagram in B depicts [[erythropoiesis]] in the [[spleen]] which approximately occurs between 10 weeks and 28 weeks of the fetal life.
|AnswerBExp=Option B depicts erythropoiesis in the [[spleen]], which typically occurs between 10 weeks and 28 weeks of gestation.
|AnswerC=C
|AnswerC=C
|AnswerCExp=The diagram in C depicts [[erythropoiesis]] in the [[liver]] which approximately starts in the fetus at 6 weeks and continues until birth.
|AnswerCExp=Option C depicts erythropoiesis in the [[liver]], which typically starts in the fetus at 6 weeks of gestation and continues until birth.
|AnswerD=D
|AnswerD=D
|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.
|AnswerDExp=Option D depicts erythropoiesis in the [[yolk sac]], which typically starts in the fetus at 3 weeks of gestation and continues until 8 weeks of gestation.
|AnswerE=E
|AnswerE=E
|AnswerEExp=This diagram is not characteristic of hematopoiesis in any organ.
|AnswerEExp=Option E is not characteristic of hematopoiesis in any organ.
|EducationalObjectives=Erythropoiesis in the liver typically starts in the fetus at 6 weeks of gestation and continues until birth.
|References=First Aid 2014 page 270.
|RightAnswer=C
|RightAnswer=C
|WBRKeyword=Erythropoiesis, fetal erythropoiesis
|WBRKeyword=Erythropoiesis, Fetal erythropoiesis, Blood, Development, Fetus, Liver
|Approved=No
|Approved=Yes
}}
}}

Latest revision as of 02:22, 28 October 2020

 
Author [[PageAuthor::Rim Halaby, M.D. [1] (Reviewed by Yazan Daaboul, M.D.)]]
Exam Type ExamType::USMLE Step 1
Main Category MainCategory::Embryology
Sub Category SubCategory::Hematology
Prompt [[Prompt::The concentrations of different types of hematopoietic stem cells are measured in various organs extracted from aborted fetuses. Shown below is an image that depicts hematopoiesis in various 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::Option A depicts erythropiesis in the bone marrow, which typically starts at 18 weeks gestation and continues throughout adulthood.]]
Answer B AnswerB::B
Answer B Explanation [[AnswerBExp::Option B depicts erythropoiesis in the spleen, which typically occurs between 10 weeks and 28 weeks of gestation.]]
Answer C AnswerC::C
Answer C Explanation [[AnswerCExp::Option C depicts erythropoiesis in the liver, which typically starts in the fetus at 6 weeks of gestation and continues until birth.]]
Answer D AnswerD::D
Answer D Explanation [[AnswerDExp::Option D depicts erythropoiesis in the yolk sac, which typically starts in the fetus at 3 weeks of gestation and continues until 8 weeks of gestation.]]
Answer E AnswerE::E
Answer E Explanation AnswerEExp::Option E 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 organs:


Shown below is an image that depicts erythropoiesis in fetuses and adults.
Fetal erythropoiesis
Educational Objective: Erythropoiesis in the liver typically starts in the fetus at 6 weeks of gestation and continues until birth.
References: First Aid 2014 page 270.]]

Approved Approved::Yes
Keyword WBRKeyword::Erythropoiesis, WBRKeyword::Fetal erythropoiesis, WBRKeyword::Blood, WBRKeyword::Development, WBRKeyword::Fetus, WBRKeyword::Liver
Linked Question Linked::
Order in Linked Questions LinkedOrder::