Human Sexual Development Quiz
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Questions and Answers

What determines genetic sex in humans?

  • Hormonal levels during development
  • Presence of the SRY gene
  • Presence of XX or XY genotype (correct)
  • Presence of gonadal tissue

    • Which process involves the development of internal and external genitalia as either male or female?

  • Phenotypic differentiation
  • Genetic determination
  • Sexual differentiation (correct)
  • Sexual determination

    • What role does the SRY gene play in sexual development?

  • It converts the gonads into testis (correct)
  • It directly creates ovaries
  • It influences the development of Sertoli cells
  • It regulates external genital morphology

    • What happens in the absence of the Y chromosome during gonadal development?

    <p>Ovaries will develop</p> Signup and view all the answers

    During which week of embryo development does the SRY gene switch on briefly?

    <p>Week 7</p> Signup and view all the answers

    What results from the products of the testis during sexual differentiation?

    <p>Formation of anti-Mullerian hormone</p> Signup and view all the answers

    Which of the following is NOT a definition of gender identity?

    <p>Enduring attraction to others</p> Signup and view all the answers

    What is the primary defect in 5 alpha reductase deficiency?

    <p>Inability to convert Testosterone to DHT</p> Signup and view all the answers

    What clinical manifestation at puberty may occur in patients with 5 alpha reductase deficiency?

    <p>Virilization due to high Testosterone levels</p> Signup and view all the answers

    In Androgen Insensitivity Syndrome, what happens to Mullerian ducts?

    <p>They undergo regression due to AMH</p> Signup and view all the answers

    How does Complete Androgen Insensitivity Syndrome typically present at birth?

    <p>As completely female with undescended testes</p> Signup and view all the answers

    What is a common initial clinical presentation of Androgen Insensitivity Syndrome in childhood?

    <p>Inguinal hernia</p> Signup and view all the answers

    What do primordial germ cells develop into?

    <p>Oocytes or sperm</p> Signup and view all the answers

    Which cells are formed from the primitive sex cords in males?

    <p>Sertoli cells</p> Signup and view all the answers

    What is the fate of mesonephric cells in male development?

    <p>Become blood vessels and Leydig cells</p> Signup and view all the answers

    When does the migration of primordial germ cells to the genital ridge start?

    <p>At 3 weeks</p> Signup and view all the answers

    What occurs in the genital ridge of a female when SRY expression is absent?

    <p>Primitive sex cords condense in the cortex</p> Signup and view all the answers

    Which structure arises from the genital ridge primordia?

    <p>Mullerian duct</p> Signup and view all the answers

    What initiates the formation of testis cords in males?

    <p>SRY gene expression</p> Signup and view all the answers

    Which statement correctly describes Wolffian ducts?

    <p>They become ducts contributing to male reproductive structures.</p> Signup and view all the answers

    What happens to the primitive sex cords in males during gonadal development?

    <p>They penetrate medullary mesenchyme to form testis cords.</p> Signup and view all the answers

    What does the term 'intersex' refer to?

    <p>An individual with some components of both male and female tracts or ambiguous genitalia</p> Signup and view all the answers

    Which of the following is a characteristic of true hermaphroditism?

    <p>Presence of both ovarian and testicular tissue</p> Signup and view all the answers

    What is the relationship between SRY gene and sexual differentiation in males?

    <p>It initiates the formation of male gonads</p> Signup and view all the answers

    What is a common term used to describe disorders of sexual differentiation?

    <p>Disorder of sexual differentiation (DSD)</p> Signup and view all the answers

    Which of the following conditions exemplifies XY sex reversal?

    <p>46, XY complete gonadal dysgenesis</p> Signup and view all the answers

    What does 'male pseudohermaphrodite' indicate?

    <p>An individual with male genotype but female external characteristics</p> Signup and view all the answers

    What surgical appearance might be observed during puberty in individuals with ovotesticular DSD?

    <p>Presence of both breasts and male features</p> Signup and view all the answers

    Which of the following accurately defines 'XX male' in the context of DSD?

    <p>Having a male phenotype with XX chromosome configuration</p> Signup and view all the answers

    What occurs in 46, XY DSD when no male hormones are made or detected?

    <p>Formation of ambiguous genitalia</p> Signup and view all the answers

    Which cells are responsible for synthesizing testosterone in males?

    <p>Leydig cells</p> Signup and view all the answers

    What influences the regression of the Mullerian ducts in males?

    <p>AMH</p> Signup and view all the answers

    In females, the Wolffian ducts will:

    <p>Regress due to lack of stimulation by testosterone.</p> Signup and view all the answers

    What is the primary outcome of DHT in males?

    <p>Growth of the penis, scrotum, and prostate</p> Signup and view all the answers

    What characterizes the development of female internal genitalia?

    <p>Involves the maturation of the Mullerian ducts</p> Signup and view all the answers

    What role do mesonephric cells play in male sexual differentiation?

    <p>Contribute to the formation of Leydig cells</p> Signup and view all the answers

    In a genetic male fetus without SRY expression, what will most likely happen to the internal reproductive structures?

    <p>The Mullerian ducts will develop into female genitalia.</p> Signup and view all the answers

    What does AMH stand for and what is its primary function?

    <p>Anti-Mullerian Hormone, inhibits Mullerian duct development</p> Signup and view all the answers

    Which of the following correctly describes the differentiation process in females?

    <p>Follows the regression of Wolffian structures</p> Signup and view all the answers

    Which pair of structures develops from the primitive sex cords in males?

    <p>Sertoli cells and Leydig cells</p> Signup and view all the answers

    What is the primary consequence of 5 alpha reductase deficiency at puberty?

    <p>Increased virilization due to high testosterone levels</p> Signup and view all the answers

    In complete Androgen Insensitivity Syndrome, what primary physical observation is made at birth?

    <p>Female external appearance with undescended testes</p> Signup and view all the answers

    What results from the absence of testosterone action in cases of Androgen Insensitivity Syndrome?

    <p>Development of female external genitalia</p> Signup and view all the answers

    What would likely happen to an individual with 5 alpha reductase deficiency in terms of external genitalia development before puberty?

    <p>Development of ambiguous genitalia or predominantly female features</p> Signup and view all the answers

    What is the typical clinical presentation of Androgen Insensitivity Syndrome during adolescence?

    <p>Primary amenorrhea and lack of body hair</p> Signup and view all the answers

    What primarily influences the expression of phenotypic sex during sexual differentiation?

    <p>The hormones produced by the gonads</p> Signup and view all the answers

    Which statement accurately describes the sequence of events in sexual determination and differentiation?

    <p>SRY gene activation leads to testicular development followed by phenotypic differentiation.</p> Signup and view all the answers

    Which of the following best describes the role of anti-Mullerian hormone (AMH) in male development?

    <p>Inhibits the development of female reproductive structures</p> Signup and view all the answers

    What is the significance of having bipotential gonads after fertilization?

    <p>They have the potential to become either testes or ovaries, depending on genetic cues.</p> Signup and view all the answers

    In which situation would an individual most likely not develop male genitalia despite having XY chromosomes?

    <p>Complete androgen insensitivity syndrome</p> Signup and view all the answers

    What is a potential outcome of the failure to activate the SRY gene during embryonic development?

    <p>Development of ovaries and female external genitalia</p> Signup and view all the answers

    Which hormone produced by the testes is crucial for masculinizing the phenotypic sex?

    <p>Testosterone</p> Signup and view all the answers

    What is the fate of the primordial germ cells during gonadal development?

    <p>They develop into Sperm or Oocytes.</p> Signup and view all the answers

    Which structures are formed as a result of the primitive sex cords in males?

    <p>Sertoli cells and seminiferous tubules.</p> Signup and view all the answers

    At what stage do mesonephric cells contribute to blood vessel formation in males?

    <p>After the interaction with the aorta.</p> Signup and view all the answers

    Which of the following describes the primary cells formed from mesonephric cells in males?

    <p>Leydig cells.</p> Signup and view all the answers

    What is the role of primitive sex cords within the developing male gonad?

    <p>They surround primordial germ cells to form testis cords.</p> Signup and view all the answers

    Which statement correctly reflects the timing of primordial germ cell migration?

    <p>Their migration completes by 6 weeks.</p> Signup and view all the answers

    What cellular change occurs in the absence of SRY expression in females?

    <p>Primitive sex cords condense in the cortex.</p> Signup and view all the answers

    What developmental fate do Wolffian ducts typically follow in the female?

    <p>They regress due to the lack of male hormones.</p> Signup and view all the answers

    Which of the following correctly identifies the role of the genital ridge primordia in gonadal development?

    <p>They give rise to the testes or ovaries.</p> Signup and view all the answers

    Which hormone is responsible for stimulating the Wolffian ducts to develop into male internal genitalia?

    <p>Testosterone</p> Signup and view all the answers

    What is the fate of the Mullerian ducts in the presence of Anti-Mullerian Hormone (AMH)?

    <p>They regress and disappear</p> Signup and view all the answers

    Which of the following accurately describes the process of external differentiation in males?

    <p>5-alpha reductase is involved in the conversion of testosterone into DHT</p> Signup and view all the answers

    What role do granulosa cells play in female sexual differentiation?

    <p>Convert androstenedione into estradiol</p> Signup and view all the answers

    In the absence of SRY, what is the outcome for a genetic male's internal reproductive structures?

    <p>Continued development of Müllerian ducts</p> Signup and view all the answers

    What is the primary role of mesonephric cells in females?

    <p>Transform into theca cells</p> Signup and view all the answers

    Which structure is responsible for the synthesis of androgens in male differentiation?

    <p>Leydig cells</p> Signup and view all the answers

    What distinguishes male external differentiation from female when DHT is present?

    <p>Development of the penis and scrotum</p> Signup and view all the answers

    What is the significant event that occurs at 7 weeks of embryonic development in terms of male differentiation?

    <p>Wolffian ducts develop under testosterone influence</p> Signup and view all the answers

    How does the presence of androgens affect the external genitalia in genetic females?

    <p>They lead to feminization of the external genitalia</p> Signup and view all the answers

    Which condition is characterized by the development of gonads with both ovarian and testicular tissue?

    <p>True hermaphrodite</p> Signup and view all the answers

    In which disorder might an infant present with ambiguous genitalia, making it difficult to determine their sex at birth?

    <p>Ovotesticular DSD</p> Signup and view all the answers

    What term is preferred over outdated labels like 'pseudohermaphrodite' in describing individuals with sexual differentiation disorders?

    <p>Intersex</p> Signup and view all the answers

    Which type of DSD is associated with the absence of male hormones in a 46, XY genotype?

    <p>Complete Androgen Insensitivity Syndrome</p> Signup and view all the answers

    What condition is described by the phenotype being female while the genotype is male due to a Y chromosome anomaly?

    <p>XY sex reversal</p> Signup and view all the answers

    How should the condition of an individual born with both ovarian and testicular tissue be classified?

    <p>Intersex</p> Signup and view all the answers

    Which genetic configuration is associated with XX male conditions?

    <p>46, XX testicular DSD</p> Signup and view all the answers

    Which condition describes a genetic male who has not produced or detected male hormones during development?

    <p>46, XY DSD</p> Signup and view all the answers

    What is the classification of a condition when someone has both male and female reproductive structures?

    <p>True hermaphrodite</p> Signup and view all the answers

    What characterizes the presence of dysgenetic testicular tissue in individuals with XY conditions?

    <p>It represents the failure of gonadal differentiation.</p> Signup and view all the answers

    Study Notes

    Intersex: Celebrating Difference

    • Intersex individuals possess variations in sex characteristics that do not fit typical binary definitions of male or female.
    • This presentation promotes celebrating diversity in sex characteristics.

    Sexual Determination and Differentiation

    • Sexual Determination: A genetically controlled process, relying on a 'switch' on the Y chromosome, for chromosomal definition of sex.
    • Sexual Differentiation: The process where internal and external genitalia develop according to sex.  These two processes are sequential.

    The Plan

    • Explain the difference between genetic and phenotypic sex.
    • Explain sex determination and differentiation.
    • Describe the process of sexual differentiation.
    • Outline some of the common causes of ambiguous (unusual) genitalia.

    Sexual Differentiation Processes

    • Sexual differentiation in humans is a complex process with several stages. 
    • Gonadal sex is determined by either the presence of testes or ovaries.
    • Presence of SRY gene is critical in determining the gonads  of males.
    • In the absence of SRY gene the gonadal tissue develops into ovaries.
    • The two processes (gonadal and phenotypic) are contiguous.

    Gonadal Sex

    • During embryonic development (at approximately the 7th week), SRY gene activity determines testis development, or, in the absence of SRY, ovarian development.
    • Once determined, different cells, Sertoli and Leydig cells in the testes, influence subsequent gonadal and phenotypic sexual development through the production of hormones, such as anti-Mullerian hormone and testosterone.

    Gonadal Development

    • At the beginning of sexual development, gonads are bipotential and their precursor cells are derived from common precursors, called genital ridge primordia (3.5 - 4.5 weeks).
    • Three waves of cells invade the genital ridge to form the gonads: primordial germ cells, primitive sex cords and mesonephric cells.
    • Primordial germ cells become sperm or oocytes.
    • Primitive sex cords give rise to Sertoli cells in males or Granulosa cells in females.
    • Mesonephric cells become blood vessels and Leydig cells in males or theca cells in females.

    Internal Reproductive Organs

    • Müllerian ducts: These are most important for a female reproductive system, and are inhibited by Anti-Mullerian Hormone.
    • Wolffian ducts: These are stimulated by testosterone in a male reproductive tract. Absence of testosterone results in their regression. Müllerian ducts develop into female internal genitalia without any hormonal influences.

    External Differentiation

    • Male: Testosterone is converted by 5α-reductase into dihydrotestosterone (DHT) in the male skin, affecting the development of the penis, scrotum, and prostate.
    • Female: In the absence of DHT, the clitoris, labia, and lower two-thirds of the vagina develop.

    5-α Reductase Deficiency

    • A situation where testosterone is produced, but not converted to DHT, impacting external genitalia development. 
    • At puberty, testosterone levels increase, inducing virilization. However, this may be delayed or mild.

    Disorders of Sexual Differentiation

    • Gonadal dysgenesis is when sexual differentiation is incomplete, usually regarding the development of gonads.
    • Intersex individuals may have a phenotype that doesn't match their genotype.
    • Intersex conditions include: true hermaphrodite (ovotesticular DSD), male pseudohermaphrodite (46, XY DSD), female pseudohermaphrodite (46, XX DSD), XX male sex reversal, XY sex reversal, ovotesticular DSD, 46, XX testicular DSD, 46, XY complete gonadal dysgenesis, 45, XO/46, XY Mixed Gonadal Dysgenesis, 46, XX DSD (affected by fetal androgen excess).
    • Terms such as "pseudohermaphrodite" are no longer used.

    Androgen Insensitivity Syndrome (AIS)

    • This condition occurs when the body doesn't respond to androgens, leading to a phenotype that is largely female despite a chromosomal male (XY) makeup. 
    • Complete AIS typically results in phenotypically female-appearing individuals.
    • Partial AIS can present with varying degrees of external genitalia ambiguity, presenting with different levels of ambiguity.
    • Genetic and physical assessments are crucial for diagnosis.

    Congenital Adrenal Hyperplasia (CAH)

    • CAH is a group of genetic disorders affecting the adrenal glands, impacting hormone production.
    • An individual with CAH might have ambiguous genitalia or other related symptoms. 
    • CAH is diagnosed using a combination of physical assessment, hormone testing and genetic testing.
    • Various forms of CAH exist, including those related to insufficient enzymes, impacting hormonal production along the path to either cortisol or aldosterone production.

    Other Factors

    • The Quigley scale, Prader scale, HCG stimulation, and various genetic defects and chromosomal and hormonal factors play a part in differences seen.
    • Several factors like the presence/absence of the SRY gene, types of hormone production and responsiveness to hormones impact sexual differentiation. 
    • Many individuals face stigmatization. There is growing awareness about celebrating differences.

    Additional Information

    • 46, XX DSD: XX females exposed to high levels of androgens in utero. Congenital Adrenal Hyperplasia (CAH) is one example of a cause.
    • Congenital Adrenal Hyperplasia (CAH): The completeness of the enzyme block varies causing different levels of hormonal impact. If absent, it can be fatal. Often diagnosed due to visible ambigious (unusual) genitalia.
    • Many forms of intersex variations exist impacting the production or action of crucial development hormones including but not limited to testosterone, DHT, and AMH.
    • Individuals display a variety of physical and developmental characteristics.
    • The concept of "normal" and typicality often fail to account for the complete spectrum of variation in sex traits and expressions.
    • The spectrum of possible conditions and symptoms related to intersex and related variations demonstrate many forms of hormonal impact and action.

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    Disorders of Sexual Differentiation PDF

    Description

    Test your knowledge on human sexual development, including the roles of chromosomes, genes, and hormonal influences. Explore concepts such as the SRY gene, Androgen Insensitivity Syndrome, and 5 alpha reductase deficiency. This quiz covers critical topics in genetics and embryology.

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