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Year 2 Medicine > Sexual Differentiation: How to Make a Boy or a Girl > Flashcards

Sexual Differentiation: How to Make a Boy or a Girl Flashcards

1
Q

Prevalence of genital abnormalities is 1 in ….

A

Prevalence of genital abnormalities is 1 in 4500

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2
Q

Example of genital abnormalities

  • 2 newborns - baby A and B
  • Both genitically male
  • doctors advise parents and perform surgery => female
    • Baby A : happy, twenties (2004); married woman
    • Baby B : never happy, years of depression, began testosterone treatment; lives as a man.
      • At fault - doctor presuming that … + … provided a solution
A

Example of genital abnormalities

  • 2 newborns - baby A and B
  • Both genitically male
  • doctors advise parents and perform surgery => female
    • Baby A : happy, twenties (2004); married woman
    • Baby B : never happy, years of depression, began testosterone treatment; lives as a man.
      • At fault - doctor presuming that surgery + hormones provided a solution
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3
Q

What makes a boy/girl involves 3 main events:

  1. Sex determination, during …
  2. Differentiation of …, week …
  3. Differentiation of … and … genital organs, after week …
A
  1. Sex determination, during fertilization
  2. Differentiation of gonads, week 5
  3. Differentiation of internal and external genital organs, after week 5
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4
Q

Sex Determination

  • Sex is determined at …
  • Inheritance of X/Y from …
A
  • Sex is determined at fertilization
  • Inheritance of X/Y from father
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5
Q

Gonad Origin and Diff

  • At week … primordial germ cells (PGCs) arise from the …
  • PGCs are …potent
  • PGC’ migrate to … … stalk to avoid becoming imprinted
  • Later return, travelling to the genital … (next to kidney) and become the … gonad
A
  • At week 2 primordial germ cells (PGCs) arise from the epiblast
  • PGCs are pluripotent
  • PGC’ migrate to yolk sac stalk to avoid becoming imprinted
  • Later return, travelling to the genital ridge (next to kidney) and become the indifferent gonad
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6
Q

Gonad Origin and Diff (2)

  • At genital …: XX PGCs replicate at …; XY PGCs replicate at the …
A

At genital ridge: XX PGCs replicate at cortex; XY PGCs replicate at the medulla

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7
Q

Gonad gender decision relies on:

  • Genetic …
  • H…

Genetic …:

  • general … factors,
    e. g. Wt1, Sf1
  • specific promoters of … development
    e. g. Sry, Sox9
  • specific promoters of … development
    e. g. Wnt-4, FoxL2
A
  • Genetic switches
  • Hormones

Genetic switches:

  • general transcription factors,
    e. g. Wt1, Sf1
  • specific promoters of testis development
    e. g. Sry, Sox9
  • specific promoters of ovarian development
    e. g. Wnt-4, FoxL2
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8
Q

Genetic switches:

  • general transcription factors,
    • e.g. W.., S..
  • specific promoters of testis development
    • e.g. S…, S…
  • specific promoters of ovarian development
    • e.g. …-4, …L2
A
  • general transcription factors,
    • e.g. Wt1, Sf1
  • specific promoters of testis development
    • e.g. Sry, Sox9
  • specific promoters of ovarian development
    • e.g. Wnt-4, FoxL2
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9
Q

Fate of Gonad Cell lines

  • Fill in blanks where arrows are (what gender, what each makes)
A
  • Left (Female) - follicular cells, oocytes, internal theca cells - future ovary
  • Right (male)- ley dig cells, Pre-spematognia, sertoli cells - future testis
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10
Q

Fate of Gonad Cell Lines

  • Female PGCs => … (primary oocytes)
  • Sex cord cells => … (support and nutrifying the …)
  • Cortex => layer of … cells => secrete … before those generated by the follicles
A
  • Female PGCs => oogonia (primary oocytes)
  • Sex cord cells => granulosa (support and nutrifying the ovum)
  • Cortex => layer of thecal cells => secrete androgens before those generated by the follicles
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11
Q

Fate of Gonad Cell Lines

  • Male PGCs => …
  • … influences definition + identity of … cells => secretion of AMH (Anti-Müllerian Hormone)
  • AMH supresses … development pathway
  • AMH induce cells in intermediate mesoderm to become … => secrete …
A
  • Male PGCs => spermatogonia
  • Sry influences definition + identity of Sertoli cells => secretion of AMH (Anti-Müllerian Hormone)
  • AMH supresses female development pathway
  • AMH induce cells in intermediate mesoderm to become leydig => secrete testosterone
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12
Q

Kidney Development

  • Origin: intermediate … (as the reproductive organs)
  • Where: between the … and … plate (each side of the aorta)
  • 3 Stages:
    • … - disappears soon after
    • … - leaves remnants
    • … - becomes kidney
A
  • Origin: intermediate mesoderm (as the reproductive organs)
  • Where: between the somites and lateral plate (each side of the aorta)
  • 3 Stages:
    • Pronephros - disappears soon after
    • Mesonephros - leaves remnants
    • Metanephros - becomes kidney
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13
Q

Pronephros stage of kidney development - what is it?

A

kidney develops and degenerates straight after (the pronephros is a rudimentary, nonfunctional kidney that appears during the third week of development (eight- to nine-somite stage) and regresses by the fifth week.)

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14
Q
  • Gonads are … at start
  • They are linked to … development
  • The middle stage of … development (…) leaves behind ducts that become integral part of the reproductive system
A
  • Gonads are indiferent at start
  • They are linked to kidney development
  • The middle stage of kidney development (mesonephros) leaves behind ducts that become integral part of the reproductive system
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15
Q

Internal Genital Organs

  • Begin differentiation at about week …, formed from a priori identical primordium structures, i.e
    • embryos of … … possess two sets of paired ducts at the start:
      • … a.k.a. Müllerian
      • … a.k.a. Wolffian

​

A
  • Begin differentiation at about week 8, formed from a priori identical primordium structures, i.e
    • embryos of both sexes possess two sets of paired ducts at the start:
      • paramesonephric a.k.a. Müllerian
      • mesonephric a.k.a. Wolffian
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16
Q

Internal Genital Organs - in female embryo​

  • In female embryo: … duct is kept due to the absence of …
  • … duct => becomes … (4)
    • …
    • …
    • …
    • upper part of the …
A
  • In female embryo: Müllerian duct is kept due to the absence of AMH
  • Müllerian duct =>
    • oviduct
    • uterus
    • cervix
    • upper part of the vagina
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17
Q

Internal Genital Organs - in male embryo

  • In male embryo:
    • … causes Müllerian duct regression
    • testosterone promotes … duct differentiation
  • … duct => becomes (3)
    • …
    • vas …
    • … vesicle
A
  • In male embryo:
    • AMH causes Müllerian duct regression
    • testosterone promotes Wolffian duct differentiation
  • Wolffian duct =>
    • epididymis
    • vas deferens
    • seminal vesicle
18
Q

External Genital Organs

  • At first embryos of both sexes show an elevated midline swelling – genital …
  • This consists of:
    • … groove (opening into the urogenital sinus)
    • paired urethral …
    • paired … swellings
A
  • At first embryos of both sexes show an elevated midline swelling – genital tubercle
  • Tubercle consists of :
    • urethral groove (opening into the urogenital sinus)
    • paired urethral folds
    • paired labioscrotal swellings
19
Q

External Genital Organs - Male

  • Some testosterone is converted into … (…)
  • This stimulates development of the …, … and external genitals (… and …)
  • Genital tubercle => …
  • Fusion of the urethral folds => spongy …
  • Labioscrotal swellings => …
A
  • Some testosterone is converted into dihydrotestosterone (DHT)
  • This stimulates development of the urethra, prostate and external genitals (scrotum and penis)
  • Genital tubercle => penis
  • Fusion of the urethral folds => spongy urethra
  • Labioscrotal swellings => scrotum
20
Q

External Genital Organs - Female

  • Absence of …
  • Genital tubercle => …
  • Urethral folds remain open => labia …
  • Labioscrotal swellings => labia …
  • Urethral groove => …
A
  • Absence of DHT
  • Genital tubercle => clitoris
  • Urethral folds remain open => labia minora
  • Labioscrotal swellings => labia majora
  • Urethral groove => vestibule
21
Q

Sexual Differentiation - Abnormalities - 6 types are:

  • C…
  • H…
  • Gonadal …
  • … abnormalities
  • Gonadal …
  • … genitalia
A
  • Chromosomal
  • Hermaphroditism
  • Gonadal dysfunction
  • Tract abnormalities
  • Gonadal descent
  • External genitalia
22
Q

Examples of Chromosomal abnormalities (sexual differentiation)

  • 2 examples are…
A
  • Turner’s syndrome
  • Klinefelter’s syndrome
23
Q

Turner’s Syndrome:

  • Monosomy, …
  • Affects how many people?
    • What gender?
  • …% non-viable embryos
  • Survivors fail to sexually mature at …
  • Exhibit several … abnormalities (next slide)
  • Diagnosis confirmed through …
A
  • Monosomy, XO
  • 1:2500 females (does not affect males)
  • 99% non-viable embryos
  • Survivors fail to sexually mature at puberty
  • Exhibit several physical abnormalities (next slide)
  • Diagnosis confirmed through amniocentesis
24
Q

3 common sign of Turner’s syndrome are:

A
  • rudimentary gonads
  • lack of menstruation
  • lack of breast development
25
_Klinefelter's Syndrome:_ * Karyotype is ..., Sex genes are ... * How many people? * What gender? * Birth appear ... * Become ... * Exhibit some features associated with ... development (e.g. ...) * Diagnosis confirmed through ...
* **47, XXY** * **1:600-1000 male births (does not affect females)** * Birth appear **normal (undetected)** * Become **infertile** * Exhibit some features associated with **female** development (e.g. **gynecomastia**) * Diagnosis confirmed through **amniocentesis**
26
_Klinefelter's Syndrome - common signs include:_
* presence of breasts * shrunken testes * deposition of fat (hips etc)
27
_Hermaphroditism_ * Named after the offspring of the Greek gods Hermes and Aphrodite * True hermaphrodite * Female pseudohermaphrodite * Male pseudohermaphrodite * **(note: these colloquial terms are used for your understanding only and not actually used in the medical profession)**
* Named after the offspring of the Greek gods Hermes and Aphrodite * True hermaphrodite * Female pseudohermaphrodite * Male pseudohermaphrodite * **(note: these colloquial terms are used for your understanding only and not actually used in the medical profession)**
28
_'True hermaphrodites'_ * Extremely ... * Born with both ovarian and testicular tissue (...) * 46XX (...+), 45X (...+) and 45X * Possible cause e.g. two ova fertilized by two sperm that fuse to form a tetragametic chimera * External genitals may be ..., or appear to be female or male
* Extremely **rare** * Born with both ovarian and testicular tissue (**ovotestis**) * 46XX (**SRY+**), 45X (**SRY+**) and 45X * Possible cause e.g. two ova fertilized by two sperm that fuse to form a tetragametic chimera * External genitals may be **ambiguous**, or appear to be female or male
29
_'Female Pseudohermaphrodite'_ * 46, .. with virilization (due to ...) * Internal sex organs are normal, inc. ... * External appearance and genitals: appear ... * Features: ... of labia; enlarged ... * Possible cause: exposure to male hormones ... (e.g. from congenital virilizing adrenal hyperplasia
* 46, **XX** with virilization (due to **androgens**) * Internal sex organs are normal, inc. **ovaries** * External appearance and genitals: **male** * Features: **fusion** of labia; enlarged **clitoris** * Possible cause: exposure to male hormones **prior to birth** (e.g. from congenital virilizing adrenal hyperplasia
30
_'Male Pseudohermaphrodite'_ * 46, .. with under... * External genitals: incompletely formed, ambiguous or clearly ... * Some features: blind-ending ..., absence of ... development, primary ... * ...: normal, malformed or absent * Main causes: * defective ... synthesis * defective ... action (e.g. receptor disorder)
* 46, **XY** with **undervirilization** * External genitals: incompletely formed, ambiguous or clearly **female** * Some features: blind-ending **vagina**, absence of **breast** development, primary **amenorrhea** * **Testis**: normal, malformed or absent * Main causes: * defective **androgen** synthesis * defective **androgen** action (e.g. receptor disorder)
31
_Androgen Insensitivity Syndrome (AIS) - Male Pseudohermaphrodite_ * A.k.a. testicular ... * Affects 1:...-... male births * (...) hormones are normal * Dysfunctional ... to these hormones
* A.k.a. testicular **feminization** * Affects **1:20000-64000** male births * (**Male**) hormones are normal * Disfunctional **receptor** to these hormones
32
_Leydig Cell Hypoplasia - Male Pseudohermaphrodite_ * Leydig cells do not secrete ... * Possible reason: body insensitive to ... * ... genitalia normally female/slightly ambiguous * No female ... genitalia (...) develops
* Leydig cells do not secrete **testosterone** * Possible reason: body insensitive to **LH** * **External** genitalia normally female/slightly ambiguous * No female **internal** genitalia (**uterus**) develops
33
_Gonadal dysfunction_ * e.g. XY gonadal dysgenesis, a.k.a. ... Syndrome * Associated with ... karyotype * Cause: alteration to ... gene * External appearance: ... (no ...) * No functional gonads (no ... differentiation) * Gonad may develop into ...
* e.g. XY gonadal dysgenesis, a.k.a. **Swyer’s** Syndrome * Associated with **XY** karyotype * Cause: alteration to **Sry** gene * External appearance: **female** (no **menstruation**) * No functional gonads (no **testicular** differentiation) * Gonad may develop into **malignancy**
34
_Tract Abnormalities_ * Some examples: * Uterine: e.g. ... uterus * Vagina: e.g. ... * Ductus Deferens: ... or ... absence, failure of ... duct to differentiate
* Some examples: * Uterine: e.g. **unicornuate** uterus * Vagina: e.g. **agenesis** * Ductus Deferens: **unilateral** or **bilateral** absence, failure of **mesonephric** duct to differentiate
35
_Gonadal Descent_ * More apparent and common in ... (...) than on ... (undescended ...) * ...: * may be unilateral/bilateral * occurs 30% ...; 3-4% term ... * descent may take place during year ... * Undescended ...: * quite ... * detected in clinical ... assessment
* More apparent and common in **males** (**cryptorchidism**) than on **females** (undescended **ovaries**) * **Cryptorchidism**: * may be unilateral/bilateral * occurs 30% **premature**; 3-4% term **males** * descent may take place during **year 1** * Undescended **ovaries**: * quite **rare** * detected in clinical **fertility** assessment
36
_External genitalia - abnormalities_ * The most common: male ... * 1:... live male births * Failure of male ... folds to fuse * Outcome: proximally displaced urethral ...
* The most common: male **hypospadia** * 1:**125** live male births * Failure of male **urogenital** folds to fuse * Outcome: proximally displaced urethral **meatus**
37
Crucial stage of sexual development is week
5
38
_The Brain and Behaviour: Sexual Differentiation_ * What also makes us a boy or girl: ... behaviour * Research from mutants revealed that the brain acquires its ‘gender ...’ not from the influence of ... hormones… * … but instead from gene ..., given the correlation between inactivation of genes from the ... chromosome and predisposition to ...
* What also makes us a boy or girl: **sexual** behaviour * Research from mutants revealed that the brain acquires its ‘gender **identity**’ not from the influence of **sex** hormones… * … but instead from gene expression, given the correlation between inactivation of genes from the **X** chromosome and predisposition to **transexualism**
39
_The Brain and Behaviour: Sexual Differentiation - Example_ * In mouse embryos, ... genes are expressed differently between male and female brain prior to advent of sex hormones (RT-PCR) * These genes are active before ... even develop, let along ..., about week ... of development
* In mouse embryos, **51** genes are expressed differently between male and female brain prior to advent of sex hormones (RT-PCR) * These genes are active before **gonads** even develop, let along **differentiate**, about week **2** of development
40
_The Brain and Behaviour: Sexual Differentiation_ * Money, J: *‘Gender identity is one’s own categorization of one’s individuality… as experienced in self awareness of one’s own mental processes and own’s actual behaviour’* * This breakthrough can potentially help surgeons to decide which gender to opt in cases of genital ... or of ...
* Money, J: *‘Gender identity is one’s own categorization of one’s individuality… as experienced in self awareness of one’s own mental processes and own’s actual behaviour’* * This breakthrough can potentially help surgeons to decide which gender to opt in cases of genital **malformation** or of **transexualism**

Year 2 Medicine (162 decks)

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