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Block 5 AR > Reproductive Systems > Flashcards

Reproductive Systems Flashcards

1
Q

What is the role of internal genitalia?

A

Transport, storage, nutrition & maturation of gametes

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2
Q

What is the role of the external genitalia?

A

Transfer of gametes

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3
Q

What is fertilisation?

A

Fusion of haploid gametes, ovum and sperm

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4
Q

When is genetic sex determined?

A

At fertilisation
XX female
XY male
Karyotype

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5
Q

When does genital development start?

A

Week 7

At similar time to gut rotation

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6
Q

Where does the Genito urinary system develop from in the three layered embryonic disc?

A

Intermediate mesoderm

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7
Q

What occurs at 3 weeks in the development of a gonad?

A

Primordial diploid germ cells arise in yolk-sac which reflect genetic sex of new individual

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8
Q

What occurs at 6 weeks in the development of a gonad?

A

Intermediate mesoderm becomes raised into paired genital ridges
Epithelium proliferates and penetrates mesenchyme to form primitive sex cords in an indifferent gonad
Germ cells migrate from yolk sac by amoeboid action and invade genital ridges and indifferent gonad
Induce development of indifferent/primordial gonad into testis or ovary

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9
Q

What state is the gonad in at week 6?

A

Indifferent/primordial

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10
Q

What happens to the indifferent gonad for it to become an ovary?

A

Germ cells are XX
Colonise cortex of primordial gonad
Surface epithelium continues to proliferate
Germ cells become surrounded by clusters of mesenchymal cells-primordial follicles
Remaining cords degenerate

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11
Q

What happens to the indifferent gonad if no germ cells arrive?

A

Cortex develops and they follow the ovary lineage

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12
Q

What happens to the indifferent gonad to become a testis?

A

Germ cells are XY (genes on Y chromosome influence subsequent
masculinisation)
Primitive sex cords continue to proliferate
Colonise medullary region of primordial gonad to form medullary or definitive sex cords
Dense tunica albuginea separates cords from surface epithelium
Sertoli cells differentiate from surface epithelium
Leydig cells differentiate from mesenchyme
Secretion of Testosterone by leydig cells in 8th week-influences further sexual differentiation of genitalia of embryo
Sex cords acquire a lumen at puberty as seminiferous tubules

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13
Q

Where do the gonads move to?

A

Gonads develop on posterior abdominal wall
Testis descends to end up in scrotum
Ovary descends to end up in pelvis

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14
Q

Describe the descent of the male gonad

A

Fold of peritoneum, processus vaginalis descends into labioscrotal folds (developing scrotum)
Passes through abdo wall, carries with it fascial layers of abdo wall
Gonad follows caudal descent as it is attached to abdominal wall by gubernaculum
Testis passes through inguinal canal into the scrotum

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15
Q

What forms the tunica vaginalis?

A

Lower part of processus vaginalis (fold of parietal peritoneum) forms tunica vaginalis

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16
Q

Why do the testis descend?

A

Testes need lower temperature of scrotum to permit maturation of sperm

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17
Q

When do testes descend?

A

28 weeks- migrate through inguinal canal
33 weeks - entering scrotum
Both testes in scrotum in 97% of male newborns at term
Gonad drags its supply lines with it

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18
Q

What is tissue is the testicle a derivative of?

A

Intermediate mesoderm derivative that develops high on posterior abdominal wall

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19
Q

Where does lymph drain to from the testicle and why?

A

Point of origin relevant to blood supply origin and lymph drainage
Blood supply & lymph vessels dragged with testicle
Lymph drains to para-aortic nodes ~L2 (not inguinal nodes)
Descends through inguinal canal (via gubernaculum)
Spermatic cord coverings = layers of anterior abdo. wall

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20
Q

What are the primordia for the male and female internal genitalia?

A 
Fetus has primordia for male and female internal ducts 
Mesonephric ducts (Wolffian) - male 
Paramesonephric ducts (Mullerian) - female
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21
Q

Describe the development of the male internal genitalia

A 
Para mesonephric (Mullerian) duct growth inhibited by Mullerian inhibitory hormone (MIH) Secreted by Sertoli cells 
Mesonephric (Wolffian) duct growth is stimulated by testosterone from leydig cells
Develops into Epididymis, Vas deferens and Seminal vesicles
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22
Q

Describe the development of the female internal genitalia

A

Paramesonephric (Mullerian) duct develops into Fallopian tubes, Uterus, Cervix, Upper part of vagina
Mesonephric (Wolffian) duct regresses spontaneously

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23
Q

What do Uterine tubes and uterus develop from?

A

Paired paramesonephric ducts

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24
Q

What can Uterine & vaginal malformations lead to?

A

Primary amenorrhoea, infertility/problematic pregnancy

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25
Q

What do the external genitalia develop from?

A

Primordia bipotential
Urethral folds
Genital swellings
Genital tubercle

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26
Q

What do the male external genitalia develop from?

A

Urethral folds develop into Shaft of penis
Genital swellings develop into Scrotum
Genital tubercle develops into glans of penis
Influenced by testosterone from gonad

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27
Q

What are key features of male external genitalia development?

A

Enlargement
Elongation
Fusion

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28
Q

What do the female external genitalia develop from?

A

Urethral folds develop into Labia minora
Genital swellings develop into Labia majora
Genital tubercle develops into Clitoris

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29
Q

What are key features of female external genitalia development?

A

Slight enlargement

No fusion

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30
Q

What happens with gonads at puberty?

A

Begin to produce increasing quantities of hormones
Gametes begin to complete their development and be released
Secondary sexual characteristics facilitate interaction between sexes

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31
Q

What are male secondary sexual characteristics?

A 
Body size 
Body composition & fat distribution 
Hair & skin 
Facial hair, male pattern baldness 
Smell 
Central nervous effects
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32
Q

What are female secondary sexual characteristics?

A 
Size - sexual dimorphism 
Subcutaneous fat distribution 
Hair & skin  
Breasts 
Sensory dimorphism
Central nervous effects
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33
Q

What determines a persons sexual phenotype?

A

Assignment at birth: External genitalia

Secondary sexual Characteristics

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34
Q

What controls development at puberty?

A

HPG axis

Hypothalamic pituitary gonadal axis

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35
Q

What is the default human sexual condition?

A

Female

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36
Q

What is gametogenesis?

A

Diploid cells separated early in embryonic life in yolk sac to form germ cells

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37
Q

What are the female and male gametes?

A

Female - ovum

Male - sperm

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38
Q

What happens to germ cells once they have colonised the gonad?

A 
After colonising gonad:
Proliferate by mitosis 
Reshuffle genetically 
Reduce to haploid by meiosis 
Mature by cytodifferentiation
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39
Q

Describe the formation of sperm

A

XY germ cells colonise sex cords - medulla of gonad
Before birth, proliferate by mitosis, forming spermatogonia which cluster around edges until puberty
Group of spermatogonia divide a fixed number of times by mitosis to form a clone of cells (about 64)
Primary spermatocytes: spermatogonia replaced by mitosis available for up to and beyond 70 years
Clone of primary spermatocytes all linked by cytoplasm
Meiosis begins: Each spermatocyte forms 4 haploid spermatids, Moving towards the lumen as it does
Spermatids are released and undergo remodelling / maturation as
they pass down tubule through rete testis, ducti efferentes and
epididymis - spermiogenesis
To form sperm-added to the semen for release into female tract

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40
Q

How long does sperm production take?

A

70 days

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41
Q

How often are new groups of spermatogonia recruited?

A

Every 16 days

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42
Q

What is the spermatic wave?

A

All stages of process of sperm production are occurring at the same time in different sections of the tubule, visible on histology
Sperm production is continuous

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43
Q

Why is sperm production continuous?

A

Exploit time limits of female fertility

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44
Q

What are the contents of semen?

A

Secretions of seminal vesicle (46-80% vol)
Secretions of Prostate (13-33% vol)
Secretions of testis and epididymis: Sperm (via vas deferens) (5%)
Secretions of bulbo-urethral glands (2-5%)

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45
Q

How are semen contents mixed?

A

Emission

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46
Q

How many sperm can be in 1 ejaculation?

A

300 million but about 50 get to site of fertilisation

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47
Q

How much semen is ejaculated?

A

1.5-4 ml

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48
Q

What are Gonads?

A

Site of gamete production
Female: ovary
Male: testis

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49
Q

How are ova formed?

A

XX germ cells colonise cortex (outer layers of gonad) oogonia
Proliferate rapidly by mitosis
Max numbers reached mid gestation 7 million, Most die during gestation
Remaining 2 million all enter meiosis before birth
Meiosis stops at early stage, primary oocyte surrounded by single layer of granulosa cells to form primordial follicle until puberty

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50
Q

By what time has a female created her entire stock of gametes?

A

Before birth

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51
Q

What happens to ova during the menstrual cycle?

A

At puberty, each month 1 or 2 complete development to mature ovum
Meiotic division only resumes at ovulation- start of short period of fertility (36hr)
Limited by number that can be supported through preparation for
fertilisation and long gestation

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52
Q

What does successful fertilisation require?

A

Right no. of gametes at right time
Male and female together at right time
Effective transfer and transport of gametes to right place
Co-ordinated by HPG hormones

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53
Q

What does successful reproduction require?

A

Fertilisation
System of support for conceptus, embryo, fetus in female tract
Birth at the right time
Co-ordinated by HPG hormones

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54
Q

What are the main hormones of reproduction?

A

H: Gonadotrophin Releasing Hormone
P: Follicle Stimulating Hormone, Luteinizing Hormone
G: Inhibin, Oestrogen, Progesterone and Testosterone

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55
Q

What is the Sella turcica?

A

Saddle-shaped depression in body of sphenoid bone of skull

serves as a cephalometric landmark which forms a seat for the pituitary

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56
Q

What is the endocrine function of the hypothalamus?

A

Most dominant portion of the entire endocrine system

Output regulates function of: Thyroid gland, Adrenal gland, Gonads

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57
Q

What is the pituitary and what are its roles?

A

Function dependent on hypothalamus
Lies at base of brain
Connected to hypothalamus by a stalk containing nerve fibers and blood vessels - median eminence
Consists of two lobes: anterior, posterior

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58
Q

What is the anterior pituitary?

A

Connected to hypothalamus by superior hypophyseal artery

Consists of groups of hormone producing glandular cells

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59
Q

What peptide hormones are produced by the anterior pituitary?

A 
Prolactin 
Growth hormone (GH) 
Thyroid stimulating hormone (TSH) 
Adrenocorticotropic hormone (ACTH) 
Follicle-stimulating hormone (FSH)
Luteinizing hormone (LH)
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60
Q

What is the advantage of the portal system between the hypothalamus and anterior pituitary?

A

Only need low levels of hormone from hypothalamus to stimulate release from pituitary

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61
Q

Describe the action of gonadotrophin releasing hormone

A

GnRH – decapeptide, Originates from cleavage of prepro-GnRH

Short half-life,

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62
Q

Where does the signal for puberty come from?

A

The brain. HPG axis

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63
Q

What are Gonadotrophins?

A

FSH (follicle stimulating hormone), LH (luteinising hormone)
Glycoproteins Secreted from anterior pituitary
Levels low after birth, but rise during puberty when pulsatile GnRH production begins

64
Q

Where does LH act in the male reproductive system?

A

Leydig cells to stimulate testosterone release

65
Q

Where does FSH act in the male reproductive system?

A

Sertoli cells to stimulate Inhibin release and increase androgen receptor expression
Leydig cells to stimulate testosterone release

66
Q

Which hormones are required for the release of sperm?

A

At puberty pulsatile GnRH stimulates the anterior pituitary to produce LH and FSH
Both (LH) and (FSH) are required to produce and release sperm

67
Q

How does LH contribute to spermatogenesis?

A

Binds to LH receptors on Leydig cells and induces them to produce testosterone
Testosterone binds to testosterone (androgen) receptor on Sertoli Cells
lining seminiferous tubules- stimulating spermatogenesis

68
Q

How does FSH contribute to spermatogenesis?

A

Binds to FSH receptor on Sertoli cells
Induces expression of androgen receptor increasing responsiveness to
androgens
Also stimulates inhibin

69
Q

What feedback loops exist with testosterone and Inhibin?

A

High levels of testosterone exert negative feedback over LH secretion acting on both hypothalamus and anterior pituitary
High levels of inhibin exert negative feedback over FSH acting primarily through anterior pituitary

70
Q

What are androgens?

A

Mainly testosterone, steroid hormone derived from cholesterol
Produced by Leydig cells
4-10mg/day in humans

71
Q

What are roles of testosterone?

A

Some migrates to seminiferous tubules
Converted to dihydrotestosterone (more active) by Sertoli cells
Some binds to androgen receptors in Sertoli cells
T from testis also acts on: Muscle, Bone, Growth, Hair, Libido, Secondary sexual characteristics, Metabolism/Adipose tissue

72
Q

Describe the HPG axis in females

A

Pulsatile GnRH
Stimulates FSH and LH release from anterior pituitary
This stimulates oestrogen and progesterone release from ovaries
Inhibin provides negative feedback

73
Q

What is the role of FSH in females?

A

Stimulates development of follicles

Stimulates secretion of oestrodiol

74
Q

What is the role of LH in females?

A

Stimulates ovulation and development of corpus luteum
Stimulates secretion of oestradiol
Stimulates secretion of progesterone

75
Q

What are the feedback loops of FSH and LH secretion by oestrodiol?

A

Negative feedback: Low to moderate circulating levels of Oestradiol
suppresses gonadotrophin levels
Positive feedback: Large increase in oestrodiol (200 to 400% higher than during
follicular phase)↑ FSH and LH surge mid cycle
Important in preparing a dominant follicle leading to ovulation

76
Q

Describe the Preparation of Follicle for Ovulation by FSH and LH

A

LH stimulates theca cells to release androgen which acts on granulosa cells
Oestrodiol levels rise and stimulate follicle
FSH stimulates granulosa cell directly

77
Q

What happens post ovulation?

A

Disrupted follicle forms corpus luteum
LH stimulates corpus luteum to secrete progesterone and oestrogen
Increase in progesterone and oestrogen as corpus luteum expands

78
Q

What endocrine changes occur at the menopause?

A

Declining oocyte numbers
Low oestradiol
High FSH and LH as hypothalamus is still releasing GnRH
Oestrogen levels decrease

79
Q

What are the roles of oestrogen?

A

Increases muscular contraction in uterine tubes and uterus to facilitate sperm passage
Proliferates uterine lining to prepare for implantation
Makes cervical mucus thin and alkaline to allow sperm entry
Supports breast development at puberty and in pregnancy
Female body fat distribution and hair
Genital lubrication
Supports bone growth

80
Q

When does menstruation occur?

A

Day 1-7 of cycle

During follicular phase

81
Q

When does ovulation occur?

A

Day 14

FSH, LH and oestrogen levels surge

82
Q

What are the phases of the uterine cycle?

A

Menses day 1-7
Proliferative phase day 7-14
Secretory phase day 14-28

83
Q

What causes the progesterone surge after ovulation?

A

Corpus luteum

84
Q

What are the functional windows in the menstrual cycle?

A

Regeneration window day 1-5 stem cell driven
Fertile window day 11-13 probability of more than 5% pregnancy
Implantation window day 19-21 endometrium becomes receptive
Selection window day 23-27 pregnancy response

85
Q

Describe the spatial organisation of the endometrium

A

Functionalis, basalis and myometrium layers
Only functionalis shed at menstruation
Blunted hormone response in the basalis
Rich in specialised immune cells such as uterine natural killer cells

86
Q

Describe actions of the myometrium

A

Hormone dependent differentiation which mirrors changes in endometrium
Forms the placental bed in pregnancy
Specialist contraction waves throughout the cycle

87
Q

What are the ACTIONS OF STEROID HORMONES ON ENDOMETRIAL CELLS?

A

Ovarian hormones act as transcription factors
Cause gene expression of chemokines, cytokines and growth factors which have autocrine, paracrine and juctacrine actions to stimulate proliferation, differentiation and apoptosis

88
Q

What is MENARCHE?

A

First period

Usually age 13 y but can be 8-16 y

89
Q

When does the menopause usually occur?

A

Age 52

Can be 45-55 y

90
Q

Which phase of the menstrual cycle is the more variable?

A

PROLIFERATIVE PHASE MORE VARIABLE: 10 – 16 D

LUTEAL PHASE: 14 D growth and degeneration of corpus luteum

91
Q

What is regular and irregular in terms of menstruation variability?

A

INTERCYCLE VARIABILITY: REGULAR ( ≤ 8 D)
IRREGULAR (> 8 - ≤ 20 D)
VERY IRREGULAR (> 20 D)

92
Q

What is Spinbarkeit?

A

Spinnability of vaginal mucus

93
Q

What changes in the cervix occur during the fertile window?

A

Thick mucus which is normally present gets thinner until it reaches a watery peak

94
Q

What is the fertile window?

A

Defined by probability of intercourse resulting in pregnancy of >5%
Spans 4 - 5 days before and 1 day post-ovulation
Involves coordinate changes in cervix (mucus, positioning, softness) Cervical changes allow estimation of fertile and infertile days

95
Q

What moves the embryo along the Fallopian tubes?

A

Fimbria

96
Q

What is required for pregnancy?

A

Depends on implantation of a developmentally competent embryo in a receptive endometrium

97
Q

Describe GENETIC DIVERSITY IN HUMAN EMBRYOS AT IMPLANTATION

A

A SIGNIFICANT PROPORTION OF HUMAN EMBRYOS ARE CHAOTIC
REMAINDER ARE LIKELY MOSAIC
VAST ARRAY OF CHROMOSOMAL ERRORS HAVE BEEN DESCRIBED
NO TWO HUMAN EMBRYOS ARE IDENTICAL AT IMPLANTATION

98
Q

What drives reproductive success or failure?

A

Natural selection and implantation

99
Q

Describe the natural selection process which occurs at implantation

A 
Spontaneous decidualization
Maternal encapsulation 
Embryo quality control  
Default rejection / menstruation  
Uterine plasticity
100
Q

What do decidual cells do?

A 
TROPHOBLAST INVASION 
HAEMOSTASIS 
IMMUNOMODULATION 
OXIDATIVE STRESS DEFENCES
PROMOTE IMPLANTATION
EMBRYO BIOSENSORING 
REJECTION & RENEWAL 
UTERINE PLASTICITY
101
Q

Describe THE IMPLANTATION WINDOW

A

IMPLANTATION WINDOW (2 - 4 D) SYNCHRONISES EMBRYO DEVELOPMENT AND ENDOMETRIAL MILIEU
SPONTANOUS DECIDUALIZATION IS LINKED TO MENSTRUATION AND PROTECTS THE MOTHER AGAINST HIGHLY INVASIVE CHROMOSOMALLY CHAOTIC EMBRYOS
DECIDUAL CELLS HAVE THE PROPENSITY TO MIGRATE AND ENCAPSULATE THE EMBRYO AND ENGAGE IN ‘SENSORING’ EMBRYO QUALITY

102
Q

What causes menstruation and regeneration?

A

Caused by progesterone withdrawal after decidualization
Acute inflammation and proteolytic breakdown of the superficial layer Cyclic menstruation starts at menarche, 1st uterine bleed occurs after brith
Menstrual blood is rich in regenerative stem-like cells

103
Q

What defines heavy periods? And how can this be assessed?

A

> 80 ML per cycle
Assessed either subjectively, pictorial blood loss assessment chart
or alkaline hematin method

104
Q

What is a major cause of endometriosis?

A

Retrograde menstruation through the Fallopian tubes

105
Q

What is dysmenorrhea?

A

Painful periods

106
Q

What is dyspareunia?

A

Pain during or after sexual intercourse

107
Q

What is mittlesmerch?

A

Pain in the middle of the cycle

108
Q

What is menorrhagia?

A

> 80 ml or > 7 d but regular

109
Q

What is menometrorrhagia?

A

Irregular menorrhagia (heavy periods)

110
Q

What is hypomenorrhea?

A

Abnormally light periods

111
Q

What is amenorrhoea?

A

Abnormal absence of menstruation

More than 3 months without a period

112
Q

What is oligomenorrhoea?

A

Infrequent periods, more than 35 days

113
Q

What is polymenorrhoea?

A

Frequent periods, less than 21 days

114
Q

What are Disorders of the Physical reproductive tract?

A 
Ovarian cysts
Adhesions
Polyp
Fibroid
Cervical intra epithelial neoplasia 
Ectopic
Hydrosalpinx (distally blocked fallopian tube with serous or clear fluid)
115
Q

What are Disorders of the Functional reproductive tract?

A

Impaired ovarian steroidogenesis
Ovary: policystic ovaries, premature ovarian failure, genetic mutations
Hypothalamus/Pituitary: stress, weight loss, drugs, hyperprolactinaemia, thyroid dysfunction
Impaired steroid hormone responses: Inflammation / impaired immune response, Exogenous hormones/ Endocrine disruptors

116
Q

What is sexuality?

A

Complex: elements of self identity and external influences during childhood and development

117
Q

What does sexual behaviour involve?

A

Physiological and psychological processes

118
Q

Why have sexual behaviours evolved?

A

Ensure meeting of gametes for fertilisation

119
Q

What is erection and what causes it?

A

Stimulus (physical or psychological)
Parasympathetic dilation of arteries
Increased blood flow compresses veins
Build-up of blood causes erection

120
Q

What is ejaculation and what causes it?

A

Sympathetic impulses
Urethra fills with semen
Contraction of muscles at base of penis
Pressure forces semen through urethra

121
Q

What are the 4 stages of coitis?

A

Excitement
Plateau
Orgasm
Resolution

122
Q

What happens to sperm after coitis?

A

Deposited in upper vagina and enter cervix
Supported by mucus components and form reservoir in cervical crypts
Swim (or are transported) into uterus and tubes
Relatively few sperm reach site of fertilisation in ampulla (few hundred)

123
Q

What do the testis and epididymis contribute to ejaculate?

A

Sperm, testosterone, L-carnitine (antioxidant affecting motility)

124
Q

What do the seminal vesicles contribute to ejaculate?

A

Fructose, proteins, semen clotting factors, interleukins, prostaglandin E

125
Q

What does the prostate gland contribute to ejaculate?

A 
Phosphate and bicarbonate buffers
Prostate specific antigen (PSA)
Coagulase (liquefying)
Zinc
Citric acid
Spermine and spermidine
Putrescine
126
Q

What do Bulbourethral 2-5% and urethral glands contribute to ejaculate?

A

Lubrication of male reproductive tract. Can include anti-sperm antibodies

127
Q

What are normal ranges for ejaculate to indicate fertility?

A 
After 3-5 days abstinence: 
Volume:  >1.5 ml 
Liquefaction time:  within 60 min 
pH 7.2 or more 
Sperm concentration: >15 million per ml 
Total sperm count:  >39 million per ejaculate 
Motility:  >32% total progressively motile (total motility >40%) 
Morphology:  >4% normal forms
Vitality:  >58% live 
White blood cells:
128
Q

Which follicles are recruited for ovulation?

A

Antral follicles

129
Q

What is a polar body of a human oocyte?

A

Where half of genetic material is ejected during meiosis

130
Q

What is the zona pelluicda?

A

Specialised extracellular matrix surrounding developing oocyte within each follicle in ovary
Formed by secretions from oocyte and follicle granulosa cells

131
Q

What are granulosa cells and what do they do?

A

Somatic cell of sex cord associated with developing female gamete in ovary
Production of sex steroids and growth factors
FSH stimulates cells to convert androgens (from thecal cells) to estradiol by aromatase during follicular phase
After ovulation, cells turn into granulosa lutein cells that produce progesterone. Maintain a potential pregnancy and causes production of thick cervical mucus to inhibit sperm entry into uterus

132
Q

What are thecal cells and what do they do?

A

Layer of the ovarian follicles which appear as they become tertiary
Theca interna responsible for production of androstenedione and indirectly estradiol, by supplying neighboring granulosa cells with androstenedione that with the help of aromatase can be used as a substrate for estradiol

133
Q

Which phase are oocytes arrested in?

A

Metaphase II

134
Q

What are essential features of sperm for fertilisation?

A

Motility - swim against action of tubal cilia
Capacitation - changes to outer glycoprotein coat
Acrosome reaction - penetrate zona pellucida

135
Q

Describe fertilisation

A

Occurs in ampulla of oviduct
Mature capacitated sperm meets metaphase II oocyte
Hyperactivation and acrosome reaction of sperm, zona penetration
Causes final maturation of oocyte/release of second polar body
Sperm binding to oolemma causes calcium transients which:
Activate oocyte for further development
Release cortical granules avoiding polyspermy

136
Q

What allows sperm entry into the zona pellucida?

A

Acrosome reaction

137
Q

What prevents polyspermy during fertilisation?

A

Release of cortical granules

138
Q

How many pronuclei should their be in a successfully fertilised egg?

A

2

139
Q

What could dispermic fertilisation result in?

A

Abnormal conceptus eg triploid

Possible abortion

140
Q

At what time does a successful embryo reach the uterus?

A

Day 4-5

141
Q

Describe the initial stages of embryo development

A 
Pronucleate 6-20 hr 
Cleavage  18hr-3 days 
Compaction 3-4 days 
Blastocyst 5-7 days 
Hatching 6-7 days
142
Q

Describe embryonic genome activation

A

mRNA inherited from oocyte supports embryo development through fertilisation and early cleavage
Onset of mRNA production from embryonic genome principally at 4-8 cell stage

143
Q

What does the inner cell mass of the blastocyst become?

A 
Becomes embryo ‘proper’ 
Undifferentiated 
Stem cell markers 
Minority of cells (~20%) 
Female imprinting important
144
Q

What does the trophoectoderm of the blastocyst become and what does it do?

A

Becomes placenta and extraembryonic features
Secretes hCG (basis of pregnancy test)
Accommdates some abnormal cells (NB prenatal diagnosis)
Invasive/adhesive
Male imprinting important

145
Q

What is implantation? And when does it occur?

A 
Around 7 days after ovulation  
Usually in upper part of uterus 
Apposition, Adhesion and Attachment 
Specific orientation and maternal/embryonic communication mechanisms 
Immunologically complex
146
Q

Which is the most likely failure stage of IVF treatment?

A

Implantation
70% failure rate per embryo
Post-implantation failure of pregnancy ~15-20%

147
Q

What is infertility?

A

1-2 years of attempting pregnancy (84% of couples in general population conceive within1 yr and 92% within 2 years if having regular sex and not using contraception)

148
Q

When does fertility begin to decline?

A

Age 30

149
Q

What can be medically diagnosed causes for female infertility?

A

Anovulation: Primary or secondary ovarian failure, Polycystic ovarian disease
Tubal disease or blockage
Uterine anomaly
Age

150
Q

What are IVF diagnosed causes for female infertility?

A 
Anti sperm antibodies
Egg anomaly (genetic, cytoplasmic, maturation)
Fertilisation failure or abnormality 
Abnormal embryo development 
Implantation problem
151
Q

What can cause Oligo ovulation or anovulation?

A 
Polycystic ovaries (common in fertile population too) 
Endocrine anomalies: high LH, high androgens, insulin insensitivity Overweight
152
Q

What can be endocrine treatments for oligo ovulation?

A

Anti or partial estrogens

FSH - ovarian stimulation, produce more eggs

153
Q

What is the aim of IVF treatment?

A

Bring gametes together more reliably rather than fix cause of infertility

154
Q

What can be male causes for infertility?

A

Impotence (Psychosexual, drug induced, paraplegia)
No sperm in ejaculate (azoospermia): testicular failure, Obstructive (vasectomy, CBAVD), Retrograde ejaculation
Not many sperm (oligozoospermia

155
Q

What are options for male fertility treatments?

A

Correct hormonal imbalances/blockages/psychological problems Obtain best sample from ejaculate
If too poor, obtain best sample from surgical retrieval
If sperm available, apply treatments to female partner in order of least invasiveness/appropriate to any female factor of infertility: Artificial insemination, Intrauterine insemination, IVF, ICSI
If no sperm available, or ICSI declined, consider donor sperm

156
Q

What is ICSI?

A

Injection of one immobilised sperm into egg avoiding presumed position of oocyte spindle near polar body
Fertilisation, embryo development and pregnancy rates similar to
IVF with normal sperm
Some increased abnormality rate, likely due to parental factors

157
Q

What are risks of fertility treatment?

A

Failure (~70% per cycle)
Over response of woman to stimulation drugs (multiple ovulation)
Multiple pregnancy
Advanced maternal age increases every obstetric risk
Psychological
Known risks of embryological processes (ICSI, sex chromosomal disorders, inheritanceof infertility, possibly imprinting disturbance)
Unknown risks of embryological processes

Block 5 AR (7 decks)

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