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{{WBRQuestion | {{WBRQuestion | ||
|QuestionAuthor={{YD}} (Reviewed by {{YD}} and {{AJL}}) | |QuestionAuthor= {{YD}} (Reviewed by {{YD}} and {{AJL}}) | ||
|ExamType=USMLE Step 1 | |ExamType=USMLE Step 1 | ||
|MainCategory=Physiology | |MainCategory=Physiology | ||
| Line 22: | Line 22: | ||
|SubCategory=Reproductive | |SubCategory=Reproductive | ||
|Prompt=A researcher studying the process of ovulation in human females recruits 10 female volunteers. He injects subcutaneously human chorionic gonadotropin (hCG) hormone and retrieves the eggs 35 hours later. Using the appropriate technique, he views the eggs under fluorescence microscopy. Under fluorescence microscopy, which of the following findings does the researcher most likely observe? | |Prompt=A researcher studying the process of ovulation in human females recruits 10 female volunteers. He injects subcutaneously human chorionic gonadotropin (hCG) hormone and retrieves the eggs 35 hours later. Using the appropriate technique, he views the eggs under fluorescence microscopy. Under fluorescence microscopy, which of the following findings does the researcher most likely observe? | ||
|Explanation=The process described above is induction of ovulation, whereby patients typically receive subcutaneous injections of hCG (a mimicker of LH) followed by egg retrieval 35-40 hours later. In this process, ovulation most likely occurs, and retrieval of oocytes is then made possible. Typically in females, cell division of oocytes is arrested at metaphase II following ovulation and prior to fertilization. Only if fertilization occurs, will the oocyte resume meiosis II. Under fluorescence microscopy, metaphase II is characterized by the presence of sister chromatids along the equatorial plate. In contrast, metaphase I is characterized by the presence of homologous chromosomes along the equatorial plate. Unlike humans, other species may produce oocytes at different stages of meiosis. | |Explanation=The process described above is induction of ovulation, whereby patients typically receive subcutaneous injections of hCG (a mimicker of LH) followed by egg retrieval 35-40 hours later. In this process, ovulation most likely occurs, and retrieval of oocytes is then made possible. Typically in females, cell division of oocytes is arrested at metaphase II following ovulation and prior to fertilization. Only if fertilization occurs, will the oocyte resume meiosis II. Under fluorescence microscopy, metaphase II is characterized by the presence of sister chromatids along the equatorial plate. In contrast, metaphase I is characterized by the presence of homologous chromosomes along the equatorial plate. Unlike humans, other species may produce oocytes at different stages of meiosis.<br> | ||
[[Image:Mitosis Meiosis Ovulation Fertilization Cell Cycle Arrest Chromosome Haploid Diploid Oogonium Ovum Oocyte Figure.png|1000px]] | |||
|AnswerA=Beginning of the disappearance of the nuclear envelope | |AnswerA=Beginning of the disappearance of the nuclear envelope | ||
|AnswerAExp=Early prophase I is characterized by the disappearance of the nuclear envelope. | |AnswerAExp=Early prophase I is characterized by the disappearance of the nuclear envelope. | ||
Latest revision as of 00:13, 28 October 2020
| Author | [[PageAuthor::Yazan Daaboul, M.D. (Reviewed by Yazan Daaboul, M.D. and Alison Leibowitz [1])]] |
|---|---|
| Exam Type | ExamType::USMLE Step 1 |
| Main Category | MainCategory::Physiology |
| Sub Category | SubCategory::Reproductive |
| Prompt | [[Prompt::A researcher studying the process of ovulation in human females recruits 10 female volunteers. He injects subcutaneously human chorionic gonadotropin (hCG) hormone and retrieves the eggs 35 hours later. Using the appropriate technique, he views the eggs under fluorescence microscopy. Under fluorescence microscopy, which of the following findings does the researcher most likely observe?]] |
| Answer A | AnswerA::Beginning of the disappearance of the nuclear envelope |
| Answer A Explanation | AnswerAExp::Early prophase I is characterized by the disappearance of the nuclear envelope. |
| Answer B | AnswerB::Alignment of the sister chromatids along the equatorial plate. |
| Answer B Explanation | AnswerBExp::Alignment of the sister chromatids along the equatorial plate occurs during metaphase II, the stage where oocyte arrest takes place following ovulation and prior to fertilization. |
| Answer C | AnswerC::Alignment of the homologous chromosomes along the equatorial plate |
| Answer C Explanation | AnswerCExp::Alignment of the homologous chromosomes along the equatorial plate occurs during metaphase I. |
| Answer D | AnswerD::Migration of sister chromatids to opposite poles |
| Answer D Explanation | AnswerDExp::Migration of sister chromatids to opposite poles occurs during anaphase II. |
| Answer E | AnswerE::Migration of homologous chromosomes to opposite poles |
| Answer E Explanation | AnswerEExp::Migration of homologous chromosomes to opposite poles occurs during anaphase I. |
| Right Answer | RightAnswer::B |
| Explanation | [[Explanation::The process described above is induction of ovulation, whereby patients typically receive subcutaneous injections of hCG (a mimicker of LH) followed by egg retrieval 35-40 hours later. In this process, ovulation most likely occurs, and retrieval of oocytes is then made possible. Typically in females, cell division of oocytes is arrested at metaphase II following ovulation and prior to fertilization. Only if fertilization occurs, will the oocyte resume meiosis II. Under fluorescence microscopy, metaphase II is characterized by the presence of sister chromatids along the equatorial plate. In contrast, metaphase I is characterized by the presence of homologous chromosomes along the equatorial plate. Unlike humans, other species may produce oocytes at different stages of meiosis.
|
| Approved | Approved::Yes |
| Keyword | WBRKeyword::Metaphase I, WBRKeyword::Metaphase II, WBRKeyword::Anaphase, WBRKeyword::Oocyte, WBRKeyword::Egg, WBRKeyword::HCG, WBRKeyword::Human chorionic gonadotropin, WBRKeyword::Meiosis, WBRKeyword::Ovulation, WBRKeyword::Fertilization, WBRKeyword::Fluorescence microscopy |
| Linked Question | Linked:: |
| Order in Linked Questions | LinkedOrder:: |
