Reproduction II PDF

Reproduction II November 20, 2023 1:20 PM Super Seven List – Reproduction (9 MCQs) 1. Oogenesis and spermatogenesis: what are they? review meiosis and clinical implications for heredity / inheritance 2. Characteristics of male and female reproductive system, sex hormones (effects on cells): main c...

Reproduction II November 20, 2023 1:20 PM Super Seven List – Reproduction (9 MCQs) 1. Oogenesis and spermatogenesis: what are they? review meiosis and clinical implications for heredity / inheritance 2. Characteristics of male and female reproductive system, sex hormones (effects on cells): main characteristics, cellular mechanism of action 3. Menstrual cycle: from gonadotropins, to ovary to hormones to endometrium 4. Fertilization (oocyte to zygote to embryo to fetus) and fetal development (reviewing timelines) 5. Hormonal induction of labour, lactation, feedback mechanisms 6. Genes, chromosomes and heredity Week 12 Page 1 - Sex is not determined until 7-8weeks GA, prior to then bipotential, cant determine unless look at karyotyping - Sex chromosome can tell us if male/female - Male gives X or Y - Females give only X - On Y chromosome, is a sex determining region of y chromosome that gives rise to what the biological information will be for the offspring Week 12 Page 2 biological information will be for the offspring - Testing producing SRY protein, which develop interstitial cells, makes testosterone, develop male external genitalia (wolffian ducts) - Sertoli cells (anti mullerian hormone, prevents female vector from being developed, i.e. ovaries, uterus etc is prevented from development), so get default of Y chromosome - XO = female, without Y chromosome, no inhibition of female, so develops female ○ Ex. Turner's syndrome - infertile, but can carry if given donor egg - XXY - will be male ex. Kleinfelter's syndrome - YO - neither male nor female b/c in absence of X, the zygote will die - In absence of Y, zygote is female - testes: ○ produce sperm, male sex hormone testosterone - Ducts: ○ ST - sperm doing division under meiosis ○ Epididymis - final maturation stage ○ Vas deferens ○ Urethra - Accessory organs: ○ Seminal vesicles (60% of secretions, fructose, PGs, alkaline solution- buffering vagina which is acidic) ○ needs fructose E for motility ○ Prostate - proteolytic enzymes (PSA), as prostate enlarges, more of enzyme is released, if prostate continues to enlarge, PSA could be higher. PSA is not a great test, and better for trending levels of PSA, instead of using the absolute value ○ Bulbourethral glands (cowper's): produces mucus to protect sperm - Penis - how sperm is ejaculated Week 12 Page 3 - ST - if take all of ducts in testes, it's approx ~2.5 football fields - Interstitial cells become leydig cells, which make testosterone--required for maturing sperm - Sertoli - in between where sperm are divided, hold onto testosterone to make it available ○ Secrete proteins to support sperm production ○ Have tight junctions between them ○ Release feedback hormone to prevent testosterone production - Sperm development occurs from the basal lamina towards the lumen of the seminiferous tubules ○ From germ cell/spermatogonium to mature sperm cells ○ Luminal fluid contains high K+ and steroid hormones Week 12 Page 4 - Fully matures in epididymis 23 chromosomes (not pairs) Sperm head consists of condensed DNA material --> acrosomal cap with enzymes to fertilize egg Mitochondrial spiral - make E, facilates motility of tail, thus need glucose for secretions Flagellum - only place in humans with flagella - Hypothalamus ○ GnRH - at puberty, GnRH is released and stimulates ant pit ○ Ant pit  LH  FSH - Same for males and females, but what happens is diff Week 12 Page 5 - Same for males and females, but what happens is diff - FSH - won't make follicles in male - Used for physical assessment at puberty - Tanner stage 3 & 4 - puberty starts (menses for females) Male hormone regulation: - As more testosterone is released, there is negative feedback to ant pit - As testosterone drops, there is less feedback, which will stimulate more release of LH ○ Testosterone converts to DHT (more potent test), together they are male pattern of development Week 12 Page 6 Week 12 Page 7 - - Test in females - Test in larynx - FSH - work on spermatogenic cells to ensure they secrete androgen binding protein(ABP), which binds to androgens (i.e. testosterone), to keep testosterone in the area high where division is happening for sperm development - With lots of testosterone: ○ Negative feedback of inhibin to ant pit to dec FSH ○ Negative feedback of testosterone to hypothalamus to dec GnRH and ant pit to dec LH secretion Uterus ready for implantation Vagina is passageway for childbirth Mammary glands - for milk production Week 12 Page 8 Ovaries - produce secondary oocytes - Primordial follicles-->primary follicle-->secondary follicle-->early tertiary follicle-->dominant follicle-->oocyte - Dominant follicle released in ovulation - Corpus luteum - regress is no fertilization Endometrium - innermost lining, made of cells that gets sloughed with menstruation Myometrium - SM layer Perimetrium - outer CT layer Week 12 Page 9 - Don’t need to know how many follicles at different stages ○ At birth 140,000 ○ 400-500 get ovulated in a female's lifetime - Ovaries are smooth surface until puberty - Changes in uterus and vaginal length - For male and female newborns, if mom is breastfeeding, the labia majora is distorted b/c under estrogen and progesterone influence ○ Males will have breast buds for same reason Week 12 Page 10 - FSH - stimulates follicle growth Ovary's key role is to produce estrogen? After proliferative phase in endometrial lining, LH is stimulated LH surge-->ovulation Ovulation-->secondary oocyte move to fallopian tube for fertilization and implant in uterus Ovary corpus luteum - secretes progesterone, which stabilized the endometrium Week 12 Page 11 - Week 12 Page 12 With day 1-5, lose innermost lining of endometrium Next cycle begins Under ovaries--estrogen is produced, which proliferates the endometrial lining As estrogen goes up, stimulates LH release (surge), then ovulation occurs and enters the secretory phase - Once lose corpus luteum, it regress, and lose progesterone - - Ex. HRT - never give estrogen unopposed w/o progesterone, create a proliferative phase only-higher risk of dysplasia and developing cancer ○ If don’t' have uterus, don't need progesterone ○ Thus if have uterus, need progesterone to complete secretory phase - If on the pill or OCP - regulate estrogen to limit the proliferative phase, and give bit of progesterone ○ Stabilize estrogen, don't allow it to climb, so no LH surge, and then withdraw progesterone at end for a withdrawal bleed - IUD - copper or device in uterus, and creates hostile envt and 99% of time have implantation Week 12 Page 13 - Where follicle is released - Corpus luteum still produces progesterone, and then w/o progesterone…withdrawal bleed? - Hcg - produced with fertilized ovum and helps keep corpus luteum to produce progesterone Week 12 Page 14 - Need acrosomal cap for enzymes to burrow into egg and fertilize egg - When secondary oocyte released, it has: ○ a corona radiata comprised of granulosa cells around the oocyte ○ A zona pellucida layer -glycoprotein rich extracellular matrix - acrosomal cap has to get past corona radiata and zona pellucida - Sperm makes holes in area to try to burrow in and when gets to oocyte binding membrane receptors, then cortical granules are released and prevent other sperm from getting in - Need 1 sperm with secondary oocyte - When 1 gets through, then binds secondary oocyte Week 12 Page 15 Week 12 Page 16 Cleavage of zygote day 1 Day 2 - 4 cells 16 cells - morula (day 4) Blastocyte, day 5, 100 cells, start to see internal section with trophoblast Blastocyst is implanted in uterine wall, and releases HCG which rescues the corpus luteum to prevent atresia, and allow it to continue to produce progesterone and estrogen - How many days after fertilization does zygote implant in uterine wall? (6-8 days) - Week 12 Page 17 - Secondary oocyte released from ovary, travels and fertilized in fallopian tubes - Problems if any strictures in tubes and have growing embryo and it gets stuck = ectopic pregnancy ○ The more replications, the more it will grow and stretch fallopian wall ○ If ruptures, lose integrity of fallopian tube - Implantation bleed ○ Light period, but actually implantation Week 12 Page 18 - HCG - rescues corpus luteum, allows progesterone to maintain pregnancy until 3-4th month ○ Progesterone and estrogen from corpus luteum:  prep mammary glands for lactation  Maintains endometrium of uterus during pregnancy (up to 3-4th month)  Preps mother's body for birth of baby - Relaxin: inc flexibility of pubis synthesis Week 12 Page 19 ○ inc flexibility of pubis synthesis  Notice at end of pregnancy, that women waddle b/c ligaments and pelvic floor muscles are relaxed ○ helps dilating cervix during labour ○ - HCG: ○ Prep mammary glands for lactation  Lactation is a positive feedback ○ Enhances growth via protein synthesis ○ Dec glucose use and inc FA use for ATP production - CRH: ○ Establishes timing of birth ○ Inc secretions of cortisol **don’t need to know feedback mechanisms** - Just prior to birth, CRH - stimulated by progesterone and works as negative feedback to inhibit progesterone release - Relaxin - inc near end of pregnancy to inc laxity of joints and pelvic areas, even with tailbone to allow passageway to in - Cervical stretch Rs signal to hypothalamus, determine when birth is happening ○ In cervix - head drops, cervical stretch is felt:  stimulates hypothalamus to release oxytocin from posterior pituitary □ Oxytocin - works on SM in uterus to inc uterine contractions □ Oxytocin also causes progesterone release from uterine wall  Progesterone causes uterine contractions - Uterine contractions cause further cervical stretch-->creating positive feedback to release oxytocin and progesterone for uterine contractions - As babe drops in cervix, cervix dilates - As labour progresses…. Week 12 Page 20 With baby, after cord is cut Need to put skin to skin, try to get breast feeding started As babe sucks on nipple: - Mechanoreceptors in nipple cause higher brain centers to stimulate hypothalamus, which causes oxytocin release from posterior pituitary AND prolactin release from anterior pituitary ○ Oxytocin = SM contraction  Oxy released helps SM contraction in breast to eject milk and helps with uterus to contract ○ Prolactin = milk secretion Let down reflex for mom, inc prolactin release which produces milk - When babe stops suckling and crying, stops reflex Ex. After birth pains - feel labour-like pains during lactation with the 2nd or 3rd delivered child Week 12 Page 21 - Karyotype - diploid chromosomal complement displayed in homologous pairs - Genotype - A person’s genetic makeup ○ genetic material of every individual, can look at specific genes that cause problems. ○ Everyone has genetic information in certain segments that tell us about eye colour, hair colour etc. - Phenotype - The expression of that genotype in the body ○ clinical manifestations, how genetic material is expressed - First degree - share the most genetic information - Second degree - less important b/c further from our own genetic material Week 12 Page 22 Dominant - one allele masks or suppresses the expression of its partner Recessive - the allele that is masked Inherited traits determined by genes on the sex chromosomes are said to be sex-linked X-linked - A gene found only on the X chromosome is said to be X-linked Many diseases are multifactorial/polygene - most phenotypes depend on several gene pairs at different locations acting in tandem. Such polygene inheritance results in continuous, or quantitative, phenotypic variation between two extremes and explains many human characteristics. Examples of polygene traits in humans include skin color, height, metabolic rate, and intelligence - chromosomes are paired, it follows that the genes in them are paired as well each of us receives two genes, one from each parent Different versions of the same genes are called alleles (ah-lēlz′). They occur at the same locus (location) on homologous chromosomes. Week 12 Page 23 - They occur at the same locus (location) on homologous chromosomes. - Alleles may code for the same or for alternative forms of a given trait. - When the two alleles controlling a trait are the same, a person is said to be homozygous (ho-mo-zi′gus) for that gene. - When the two alleles are different, the individual is heterozygous (het″er-o-zi′gus) for the gene. - Alleles are alternative forms of genes - Homozygous - both recessive alleles **don't need to know anything beyond this point** - If have genetic info, will become dominant Ex. Freckles Tongue toller Marfan's Huntington's - late onset ○ 50%, 1 in 2 pregnancies that offspring will have HD--50% chance in each pregnancy - Both parents are carriers of gene ○ 1 in 4 chance that child gets the disease ○ 50% chance that child is carrier ○ Problem with siblings or first cousin Week 12 Page 24 - Don't need to know Week 12 Page 25 Week 12 Page 26 - Ex. DS - trisomy 21, there's a wide variation in presentation Deletions Multifactorial - variety of genetic information that inc risk Mitochondrial - use to think mitochondrial DNA comes from only maternal, but now research showing it coems from both Screening: - Diagnosis - Susceptibility - risk of getting disease, but doesn't mean you will get the disease ○ Ex. VRCA 1 & 2 - linked to breast and ovarian CA  Choose to have hysterectomy and remove mammary glands --but does this change chance of getting ca? b/c still have some residual tissue after surgical removal  The best plan of action is a heighted screening and surveillance Research - Benefits - look at genetic information Week 12 Page 27 1. b/c of rejection, 2. At least 1 3. Adoption, stepkids, surrogate, donor egg, errors in the lab test? Week 12 Page 28 Week 12 Page 29 Week 12 Page 30