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Flashcards in Repro Session 1 Deck (131):
1

What compromises the male internal genitalia?

Testes, epididymis, vas deferens, urethra, seminal vesicles, prostate gland and bulbourethral glands

2

What comprises the female internal genitalia?

Ovaries, Fallopian tubes, uterus, cervix and vagina

3

What comprises the male external genitalia?

Penis and scrotum

4

What comprises the female external genitalia?

Vagina, vestibule, labia minora and majora and clitoris

5

What are the male secondary sexual characteristics?

Larger body size, body composition and fat distribution, facial hair, male pattern baldness, CNS effects and smell

6

What are the female secondary sexual characteristics?

Smaller body size, SC fat distribution, breast and hair development, CNS effect

7

How does the development of both male and female reproductive tracts broadly start?

At an indifferent stage with a gonad and duct system

8

When do structural and functional development of the reproductive tracts occur?

Structural in utero
Functional after birth in childhood, adolescence and puberty

9

What is the urogenital ridge?

Region of intermediate mesoderm that gives rise to the embryonic kidney and indifferent gonad

10

Where do the cells of the primitive gonad originate from?

Stroma/parenchyma from intermediate mesoderm supported by primordial germ cells from yolk sac

11

How do primordial germ cells end up in the indifferent gonad?

Arise in yolk sac in week 3 and migrate into the retroperitoneum along the dorsal mesentery

12

Why are retroperitoneal germ cell tumours seen in the gonads?

Indifferent gonads develop in the retroperitoneum

13

How is the indifferent gonad developed in the genetic male?

Male gamete carries Y chromosome --> XY conceptus --> primordial germ cells carry Y --> expression of SRY genes on Y leads to male transcription factors

14

How does the indifferent gonad develop in the genetic female?

Male gamete carrying X chromosome --> XX conceptus --> no SRY gene zone and therefore development of female

15

How does the medullary cord differ in the male and female?

Develops in male, regresses in female

16

How do the cortical cords differ in the male and female?

No cortical cords in male, they develop in the female

17

Why does the ovary not have a tunica albuginea?

Oocytes have to migrate outside gonad

18

What does the fate of the mesonephric and paramesonephric ducts depend on?

Whether there is an ovary or testis present

19

Where do the mesonephric and paramesonephric ducts end?

Cloaca

20

What is the alternative name for the mesonephric duct?

Wolffian duct

21

What combines with the mesonephric duct to form the embryonic kidney to give a primitive renal function?

Mesonephric tubules

22

Where is the mesonephric duct positioned?

Close to the primitive gonad and making contact with the cloaca caudally

23

What prevents regression of the Wolffian duct?

Male sex hormones from Leydig cells

24

What is the paramesonephric/Mullerian duct?

Invaginations of the urogenital ridge that enlarge and pull peritoneum into the midline to form the uterus

25

What allows development of the paramesonephric duct?

Absence of Mullerian inhibiting substance form Sertoli cells

26

Where do the paramesonephric ducts have openings?

Caudally at the cloaca and cranial into the abdominal cavity

27

Why can the paramesonephric duct open into the abdominal cavity?

Lack draining function

28

How do the external genitalia appear at 7 weeks?

Indifferent: genital tubercle, genital folds surrounding opening of urogenital sinus and genital swellings

29

What is the result of presence of dihydrotestosterone on external genitalia?

Genital tubercle elongation, fusion of genital folds on ventral surface, fusion of genital swellings

30

What does fusion of the genital folds and swellings form respectively?

Spongy urethra and scrotum

31

What is the result of lack of testis derived androgen on the external genitalia?

Genial tubercle doesn't elongate, genital folds do not fuse, genital swellings do not fuse and the urethra opens into the vestibule

32

What are the fates of the components of the indifferent gonad in the absence of testis derived androgens?

Genital tubercle --> clitoris
Genital folds --> labia minora
Genital swellings --> labia majorum

33

Describe the descent of the testis.

Appear retroperiotneally high up on posterior abdominal wall
--> processus vaginalis creates path for testes to be guided by the gubernaculum anterior to the pubic symphysis

34

What is the processus vaginalis?

Outpouching of peritoneum

35

What is the round ligament of the uterus?

Adult remnant of gubernaculum that attaches the ovary inferiorly to the labio-scrotal folds

36

Why is the round ligament of the uterus seen in the inguinal canal?

Tethered to labio-scrotal folds

37

Why does the ovary not move any more inferiorly that the pelvis?

It is tethered by ligaments

38

What does gestation depend on?

Placental support within female reproductive tract

39

What are hermaphrodites?

Individuals that have both ovarian and testicular tissue

40

If a hermaphrodite has the genotype 46, XX what do they usually have?

Uterus

41

Are hermaphrodites typically male or female in terms of genital development?

Either

42

Describe the hormone derangement in congenital adrenal hyperplasia.

Low steroid hormone production by the adrenals and hence high ACTH production

43

Which two processes can be affected in congenital adrenal hyperplasia?

21-hydroxylation or more rarely 17-alpha-hydroxylation

44

How might females affected by congenital adrenal hyperplasia present?

Parietal masculinisation with large clitoris, virilisation with male appearance, female internal and external genitalia but failure of secondary sexual characteristics

45

What is inhibited in males affected by congenital adrenal hyperplasia?

Virilisation

46

What happens in androgen insensitivity syndrome?

Males that have a Y chromosome and testis but lack of receptors to/response to dihydrotestosterone --> no male genitalia but paramesonephric duct is suppressed

47

How may an individual affected by complete androgen insensitivity syndrome present?

Short/poorly developed vagina, testes in inguinal or labial regions but no spermatogenesis

48

What does complete androgen insensitivity syndrome increase the risk of?

Testicular tumours

49

Describe the spectrum of effects seen in mild/partial androgen insensitivity syndromes.

Mild--> virilisation
Partial --> ambiguous genitalia
Tested are usually undescended

50

What happens in 5-alpha-reductase deficiency?

Testosterone is not converted to dihydrotestosterone therefore causing ambiguous genitalia in males with hypospadias/clitoromegaly

51

Describe Klinefelter syndrome.

47, XXY causing decreased fertility, small testes, decreed testosterone +/- gynaecomastia

52

Describe Swyer syndrome (XY female gonadal dysgenesis).

Point mutations/deletion of SRY gene so pts appear to be female but do not menstruate or develop secondary sexual characteristics

53

Describe Turner syndrome.

45, X with gonadal dysgenesis, short stature, high-arched palate, webbed neck, shield-like chest, cardiac and renal abnormalities and inverted nipples

54

What are the features of gonadal dysgenesis?

Oocytes absent, ovaries are streak gonads, phenotypically female with a variety of chromosomal complements

55

What are hypospadias?

Incomplete fusion of the urethral folds allowing abnormal openings of the urethra along the inferior aspect of the penis

56

Where are the abnormal openings in hypospadia usually seen?

Near the glans, shaft or base

57

What is epispadia?

Urethral meatus is on the dorsum of the penis

58

What causes micropenis?

Insufficient androgens due to primary hypogonadism, hypothalamic or pituitary disorder

59

What is the result of the genital tubercle splitting in the male?

Bifid penis

60

How do duplications of the uterus arise?

Lack of fusion of the paramesonephric ducts in a local area or along the entire line of fusion

61

What is uterus didelphys?

Double uterus

62

What is uterus arcuatus?

Slightly indented uterus due to failure of paramesonephric duct fusion

63

Describe uterus bicornis.

2 horns enter common vagina

64

What causes cervical/vaginal atresia?

Complete or partial atresia of the paramesonephric ducts

65

Once germ cells have colonised the gonads, what processes do they undergo to form mature gametes?

Mitosis, meiosis and cytodifferentiation

66

Compare spermatogenesis with oogenesis.

Spermatogenesis: huge number of gametes produced continuously with essentially disposable cells.
Oogenesis: few gametes produced intermittently with each having ~1/400th of the total reproductive potential of the female

67

Briefly describe the 4 steps of meiosis.

Prophase: chromosomes condense, crossing over occurs
Metaphase: homologous pairs align
Anaphase: pairs separate
Telophase: 2 daughter cells formed

68

What are the two main functions of meiosis in gametogenesis?

Reduce hormosome number to 23 and ensure each gamete is genetically unique

69

What are the products of meiosis in oogenesis?

1 mature oocyte and 3 polar bodies

70

Why are polar bodies formed in oogenesis?

To maximise cytoplasm and nutrients present into one cell

71

What is crossing over in meiosis?

Exchange of regions of DNA between 2 homologous chromosomes

72

What is random segregation in meiosis?

Random distribution of chromosomes among 4 gametes

73

How does independent assortment give rise to genetic variation?

2 homologous chromosomes of a pair must go into separate gametes

74

What is the raw material for spermatogenesis?

Soermatogonia

75

When does spermatogenesis occur in the male?

Begins around puberty and is available for up to 70 years

76

What are the products of spermatogonia undergoing mitosis?

Ad spermatogonium and Ap spermatogonium

77

What is the function of ad spermatogonium?

To maintain stock

78

What is an alternative name for Ap spermatogonium?

Primary spermatocytes

79

What happens to primary spermatocytes to give spermatids?

Divide by meiosis to give secondary spermatocytes and then to spermatids

80

What happens to the 4 haploid spermatids from each primary spermatocyte?

Differentiate by spermigenesis (cytodifferentiation) into spermatozoa

81

Where does spermatogenesis take place?

Seminiferous tubules of the testis

82

What splits the testis into the basal and adluminal compartments?

Tight junctions between Sertoli cells (blood testis/Sertoli cell barrier)

83

What is the purpose of the blood testis/Sertoli cell barrier?

Separate hormones needed for maturation and surface markers on gametes that could stimulate an immune response (as they are not self)

84

What is the function of the rete testis?

Concentrate sperm

85

What is the function of the head of epididymis in spermatogenesis?

Final maturation and storage for 2-3 months

86

Describe the pathway of sperm in the testes.

Seminiferous tubules --> rete testis --> ductili efferentes --> head of epididymis

87

What is the spermatogenic cycle?

Time taken for reappearance of the same stage of spermatogenesis within a given segment of seminiferous tubule

88

What is the spermatogenic wave?

Distance between the same stage of spermatogenesis in a seminiferous tubule

89

What causes the spermatogenic wave?

Each stage of spermatogenesis follows in an orderly sequence along the length of the seminiferous tubule

90

What is spermiation?

Spermatids moving into the lumen of seminiferous tubules

91

What happens to spermatids as they travel through the testis?

Remodelled

92

How are spermatids transported?

Sertoli cell secretions and peristaltic contraction up until epididymis where they become motile

93

Where is the energy for spermigenesis mainly derived from?

Fructose

94

What are the origins of the different components of semen?

Seminal vesicle secretions (~70%)
Secretions of prostate (~25%)
Sperm via vas deferens (2-5%)
Bulbourethral/Cowper gland secretions (

95

What is found in seminal vesicle secretions?

A.a., citrate, fructose and prostaglandins

96

What is found in secretions of the prostate in semen?

Proteolytic enzymes and zinc

97

How many sperm are released from the vas deferens per ejaculate?

~200-500 million

98

What is the function of mucoproteins found in bulbourethral/Cowper gland secretions?

Help lubricate and neutralise acidic urine in the distal urethra

99

What is sperm capacitation?

Conditions of femal genital tract allowing sperm to become fertile

100

What occurs in sperm capacitation?

Removal of glycoproteins and cholesterol, activation of sperm signalling pathways and acrosome reaction on binding with zona pellucid a

101

What is used in the sperm signalling pathway?

Atypical soluble adenylyl cyclase and PKA

102

What happens when the first sperm binds to the zona pellucida?

Initiation of calcium wave to prevent polyspermy

103

What must sperm be incubated in for human IVF?

Capacitation media

104

When has the female developed her entire stock of gamete potentials?

Before birth

105

What do germ cells differentiate into once they have colonised the primitive gonad in the female?

Oogonia

106

Where are the oogonia found?

Near the surface epithelium of the ovary

107

How do oogonia become primary oocytes?

Enter meiosis and arrest in prophase I

108

What happens to the majority of oogonia in the developing ovary?

Proliferate by mitosis to be arranged in clusters surrounded by flat epithelial cells

109

What happens in the female ovary at mid-gestation?

Maximum number of germ cells has been reached and many oogonia and primary oocytes undergo atresia

110

What has happened by the 7th month of gestation in the ovary?

Majority of oogonia have degenerated, ~2 million primary oocytes have entered meiosis I and are individually surrounded by flat epithelial cells to from primordial follicles

111

What happens to primordial follicles in the ovary?

Remain arrested (diplotene stage) until puberty

112

How many oocytes usually pass through the3 stages of maturation before only 1 or 2 are released by ovulation?

15-20

113

What are the 3 stages of oocyte maturation?

Pre-antral, Antral stage and preovulatory stage

114

What happens during the preantral stage of oocyte maturation?

Primordial follicles begin to grow, follicular cells become cuboidal and proliferate, stratified epithelium of granulosa cells is formed and the granulosa cells secrete the zona pellucida onto the oocyte

115

What happens during the Antral stage of oocyte maturation?

Fluid filled spaces appear between granulosa cells and coalesce to form the antrum, granulosa cells surrounding the oocyte (cumulus oophorus) nurse ovum

116

How many follicles begin to develop with each ovarian cycle?

Several

117

Which cells in the developing follicle express LH receptors?

Theca interna and granulosa

118

What causes the preovulatory stage of oocyte maturation?

LH surge

119

What happens in the preovulatory stage of oocyte maturation?

Meiosis I is completed, cell enters meiosis II but arrests in metaphase ~3 hours before ovulation and will only be completed if the oocyte is fertilised, otherwise it degenerates 24 hrs after ovulation

120

What forms the first and second polar bodies in the preovulatory stage of oocyte maturation?

Meiosis I and II respectively

121

What happens to the polar bodies formed during oogenesis?

Reabsorbed

122

What stimulates rapid follicular growth several days before ovulation?

FSH and LH

123

What is the Graafian follicle?

Mature follicle of ~2.5 cm diameter

124

What are the consequences of the LH surge on ovulation?

Increases collagenase activity, prostaglandins increase the LH response and cause local ovarian wall contractions

125

What forms the corpus luteum?

Remaining granulosa and theca interna cells after ovulation that become vascularised and luteinised

126

What is the action of the corpus luteum?

Secrete oestrogens and progesterone to stimulate uterine mucosa to enter secretory stage in preparation for embryo implantation

127

What happens to the corpus luteum if fertilisation does not occur?

Dies and is reabsorbed by the ovary after 14 days forming fibrotic scar tissue (corpus albicans) that decreases progesterone precipitating menstrual bleeding

128

How is oocyte transport achieved?

Fimbriae sweeping over ovary before ovulation, rhythmic contraction of uterine tube and motion of cilia in epithelial lining

129

How long does it take an oocyte to travel from the ovary to the uterine lumen?

3/4 days

130

What happened to the corpus luteum if the oocyte is fertilised?

hCG secreted by embryo prevents its degeneration allowing it to grow into the corpus luteum graviditatis that continues to secrete progesterone until the placenta takes over ~month 4

131

Where does the last stage of meiosis II in oogenesis occur?

Oviduct