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FHB Block 4 > Reproduction 1 > Flashcards

Reproduction 1 Flashcards

1
Q

describe the determinants of sexual differation

A

The type of sex: genetic, genotypic, or chromosomal
determines

gonadal sex: ovaries+/-female fetal tract or testis+/-male fetal tract
determines

genital or phenotypic sex with external sexual characteristics - most importantly external genitalia from lower fetal tract development
determines????

gender identification

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2
Q

What are the characteristics of genetic/genotypic/chromosomal sex and how is it identified?

A

determined by sex chromosome endowment: XX, XY (especially the Y determined at fertilization)

Karyotyping

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3
Q

What are the characteristics of gonadal sex and how is it identified?

A

determined by normal differentiation and especially the activation of SRY/TDF to yield male at about 7 weeks and female at 11 weeks

histology of gonads

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4
Q

What are the characteristics of genital/phenotypic sex and how is it identified?

A

determined by the activation and integration of

  1. neuroendocrine axes
  2. paracrine, endocrine control of genital tract development

physical exam

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5
Q

What are the characteristics of gender identity?

A

independent of genotype, unknown

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6
Q

discuss the general male genetic identity

A

Y chromosome required for testicular development with rare exceptions

Sry - sex determining gene on Y chromosome
XY with no Sry develop ovaries
XX with added Sry develop testis
X chromosome encodes androgen receptor

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7
Q

discuss the general female genetic identity

A

Ovary development depends on XX and no Y

Loss of one X results in ovarian dysgenesis but no loss of female ducts or genitalia

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8
Q

When do primordial germ cells migrate to the gonadal ridge?

A

5-6 weeks of gestation

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9
Q

is the gonadal ridge male or female specific?

A

neither - it is indifferent

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10
Q

What are the gene factors that determine maleness?

A

Sry is a transcription factor for Sox9, which induces proliferation of the primitive sex cords

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11
Q

What are the gene factors that determine femaleness?

A

Rspo1 and Wnt4 drive developmental progression, but ovary development will occur regardless due to lack of Sry

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12
Q

What do female internal genitalia develop from?

A

the cortex of the gonadal ridge

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13
Q

What do male internal genitalia develop from?

A

the medulla of the gonadal ridge

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14
Q

What are the three structures of the indifferent duct system?

A

mesenephros
mullerian duct
wolffian duct

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15
Q

What is the function of the mesenephros

A

produces urine during 6-10 weeks gestation and acts as a transient kidney for the developing fetus

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16
Q

What induces the regression of the mullerian duct in males?

A

AMH and inhibin B made by sertoli cellls

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17
Q

What stimulates the formation of internal genitalia in males?

A

Testosterone and DHT - androgens formed by Leydig cells

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18
Q

What induces the regression of the wolffian duct in females?

A

absence of testis, not the presence of ovaries!

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19
Q

What does the mullerian duct differentiate into in females?

A

top: fallopian tubes
middle: uterus
bottom: cervix and upper third of vagina

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20
Q

What does the genital tubercle develop into?

A

males: glans penis
females: clitoris

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21
Q

what doe the urogenital folds develop into?

A

males: ventral penis
females: labia minora

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22
Q

What does the urogenital sinus develop into?

A

males: prostate
females: lower vagina

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23
Q

What do the labioscrotal folds develop into?

A

males: scrotum
females: labia majora

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24
Q

What do the penis, scrotum, and prostate require?

A

The conversion of testosterone into DHT

25
Q

What causes developmental defects in male external genitalia?

A

inhibition or mutation in converting enzyme 5-alpha-reductase

26
Q

What are some general features of mitosis?

A

somatic cells only. daughter cells are genetically identical

27
Q

What are some general features of meiosis I?

A

germ cells, duplication of DNA, recombination of chromes = genetic diversity. Chromosomes split in meiosis I

28
Q

What are some general features of meiosis II?

A

no duplication, chromatids split, 4 daughter cells

29
Q

What are the three main cell types in the testes?

A

gametes: sperm
sertoli cells: secrete AMH and inhibin B
Leydig cells: synthesize and secrete testosterone/DHT

30
Q

What are the cell types of the ovaries?

A

Gametes (ova) and follicular cells are the follicles

31
Q

What does follicular maturation result in?

A

Granulosa cells – secrete and synthesize estrogens and progesterone

Thecal cells – make androgens

32
Q

What does DHT stimulate development of?

A

prostate and external genitalia

33
Q

What does testosterone stimulate development of?

A

male internal genitalia

34
Q

What does the wolffian duct differentiate into in males?

A

top: epididymus
middle: ductus deferens
bottom: seminal gland, ejaculatory duct

35
Q

What is unique about Meiosis I in females?

A

arrested at diplotene of prophase until activation (puberty to 45+ years)

36
Q

What causes meiosis arrest, and what produces it?

A

Oocyte maturation inhibitor (OMI), secreted by follicular cells in ovary

37
Q

what is unique about meiosis II in females?

A

arrested at metaphase II until fertilized by sperm

38
Q

discuss spermatogenesis in males

A

ongoing process from puberty through old age

39
Q

discuss some structural errors that can result in chromosome abnormalities?

A

translocations: equal or unequal exchange of chromosomal material
inversions: piece of chromosome gets inserted upside down

deletions/duplications: loss or addition of part of a chromosome

rings: two ends of chromosomes attached to form a ring

40
Q

what can happen if part of the Y chromosome containing the Sry gene gets translocated to the X?

A

XX female with male phenotype due to presence of Sry gene - this happens because X is inactivated

XY with female phenotype due to lack of Sry gene

41
Q

What is the genotype of Turner’s Syndrome?

A

XO

42
Q

What is the genotype of Klinefelter’s Syndrome?

A

XXY

43
Q

What is Klinefelter’s Syndrome usually a result of?

A

meitotic non-disjunction

44
Q

What is Turner’s Syndrome characterized by?

A

Gonadal dysgenesis - ovaries do not develop and become a streak of fibrous tissue

Although one X becomes inactivated later in life, and thus only one is necessary for life, at this stage you must have both Xs for ovary development

45
Q

Discuss some physical presentations of a person with Turner Syndrome

A

Short statue, shield chest, webbed neck, upper torso deformities. Most do not go through puberty or have menstrual cycles

46
Q

Discuss some physical and hormonal traits of someone with Klinefelter’s Syndrome

A

Patients have a Y chromosome - testes are present but are small and hyalinated, and they are infertile

Testosterone is low due to testicular dysfunction

Gynecomastia: elevated estradiol

micropenis, eunuchoid body: lower body > than upper body by at least 2” with short arms

47
Q

What is the genetic etiology of hermaphroditism?

A

60% XX
20% XY
20% mosaicism/chimerism

48
Q

What is the phenotype of hermaphroditism?

A

male/female designation is based on which gonad is present (internal or external for males)

49
Q

What is male pseudohermaphroditism?

A

Testes present, but some or all female internal/external genitalia also present

50
Q

What is an example of male pseudohermaphroditism?

A

Androgen resistance due to loss (complete) or mutation (partial) in X-linked androgen receptor gene (karyotype 46, XY)

51
Q

discuss the hormonal and phenotypic traits of male pseudohermaphroditism due to complete androgen resistance

A

Y chromosome induces mullerian duct regression and testes (undescended)

lack of androgen effects (no Wolffian duct development, no external genitalia)

hormones: androgen levels are high due to lack of feedback, high estrogens lead to development of female body characteristics
phenotype: female with blind vaginal pouch

52
Q

discuss the hormonal and phenotypic traits of male pseudohermaphroditism due to partial androgen resistance

A

Y chromosome induces mullerian duct regression and testes (undescended)

Wolffian duct develops, gynecomastia

hormones: Androgen levels are high due to lack of feedback, estrogen levels high (for male)
phenotype: ambiguous with blind vaginal pouch (under masculinized)

53
Q

What is female pseudohermaphroditism?

A

Ovaries present, but some or all male internal/external

genitalia also present

54
Q

female pseudohermaphroditism is a result of what?

A

Developmental defect – not due to chromosomal abnormality

55
Q

What is the phenotype of female pseudohermaphroditism?

A

Virilization due to increased androgens. Ambiguous genitalia, advanced skeletal age

56
Q

What are some examples of female pseudohermaphroditism?

A

Fetal congenital adrenal hyperplasia ** most common

Maternal androgen excess due to adrenal or ovarian tumors, possibly also due to progestational drugs (birth control)

57
Q

what is “true” hermaphroditism?

A

Both testes and ovaries present “gonadal” sex, but phenotypic sex ambiguous (XX hermaphrodites typically raised as females)

Cryptorchidism (undescended testes) and hypospadias are common

No spermatogenesis because other Y genes not present

58
Q

what might be a cause of true hermaphroditism?

A

Possible SRY translocation or loss of RSPO1 gene (testes repressor)

FHB Block 4 (13 decks)

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