Reproduction & Development

Fertilization: Sperm million haploid sperm cells swim to uterine tube 30 min-2hrs only 10,000 sperm reach the uterine tube Live for up to 48 hours waiting for oocyte (egg)…only 100 reach the oocyte Acrosome cap w/enzymes Flagellum falls off once enters egg

Fertilization: Oocyte Oocyte 2000x larger than sperm Found in upper 1/3 of uterine tube w/in one day if ovulation Several sperm required to penetrate corona radiata Only one sperm can penetrate the zona pellucida Then enzymes prevent other sperm from entering This activates oocyte to complete meiosis

Gestation: Prenatal Development Cleavage –(day 1-6) –mitotic cell divisions as travels down uterine tube –w/in 30hrs zygote divides to form blastomeres –Blastomeres divide every hrs –Day 3 – morula – solid ball of cells –Day 5-6 blastocyst – hollow ball of cells, cells begin to differentiate

Gestation: Implantation Implantation Day 7-10: blastocyst adheres to uterine lining Days 10-12: differentiation continues to form Amniotic cavity, Yolk sac (blood cell formation), and germ layers Germ layers: –Endoderm –Mesoderm –Ectoderm

Gestation: Placentation Placenta – allows diffusion between fetal and maternal circulation (blood barrier) By week 3 – Placenta begins to form –Produces hCG – prevents mensus By week 4 – yolk sac shrinks and fuses into umbilical cord By week – placenta produces estrogens and progesterone, ovaries become non functional

Labor & Delivery Dilation –avg 15 hrs –Cervix dilates –Contractions 10 – 30 minutes –Amnion ruptures - “water breaks” Parturition: expulsion of fetus –Less than 2 hrs –Cervix pushed open by fetus –Full dilation 10 cm –If canal is too small – Dr performs episiotomy Placental After-birth –Less than 1 hr –Muscle tension in uterus and shrinking of uterus tears placenta away from uterine wall, placenta is ejected (blood loss)

Premature Labor < 14 oz – underdeveloped, no chance of survival Between weeks – may survive, but with developmental abnormalities weeks - survival w/normal development

Multiples 1/89 Twins –70% dizygotic – “fraternal” 2 eggs fertilized at the same time –30% monozygotic – “identical” splitting of blastomere –Conjoined twins - incomplete splitting of blastomere (share skin, liver, other organs) 1/7921 triplets

First Trimester Embryonic development 3-4 weeks –Neural tube begins 5 weeks –2mm –“c” shaped –Heart bulge –Functional yolk sac & placenta 6-7 weeks –.5” (tadpole w/gills slits) –Heart beats –Neural tube closes –Arm & leg buds –Lungs, nostrils, lenses, and dig tract forms 8-10 weeks –1” –Muscles – 1 st movements –Ovaries/testes form –Fingers/toes, ears/lips develop –Bones ossify weeks (Fetus) –2-3” –Nails, vocal chords, kidneys (urine), and ears –Reflexes, hiccups (diaphragm), rollover, stretch –Pancreas, gall bladder, wbc Maternal Development Fatigue Morning sickness Tender breasts Decreased bp, lightheaded & dizzy Blood volume increases Require 10-30% more nutrients and vitamins Frequent urination

Second Trimester Fetal Development wks –4-6” (lobster tail) –Fingerprints, auditory ossicles, teeth, hair & eyebrows –Make faces, eyes move & detect light –Suck thumb wks –8-10” (small grapefruit) –Taste buds, –sense touch, and stress –Perm teeth –Myelination of ns –L/R handed –Ovaries produce eggs wks –11-15”, 2lbs (bag coffee) –Recognize voices and respond –Fat deposited –Skin pigmented –Adv. brain functions Maternal Development 90% chance full term Incr. mucosal secretions Increase breast size Pelvis spreads Pressure on organs Feel baby move Indigestion & heartburn By end: others can feel baby

Third Trimester Fetal Development wks –15-16”, 3.5 lbs –Fully developed (except brain, lungs, liver) –Movements increase wks –17-20”, 5lbs –Synapse brain & nerves –Head down position –Adding fat wks –21-23”, 6-10lbs –Testes descend into scrotum –Receiving antibodies –When ready: placenta incr. estrogen, increases oxytocin, stim contractions –Contractions start at top uterus and spread –Moves lower back into pelvis Maternal Development Back pain Swelling Itchy skin Hemorrhoids High bp Visible kicks/punches Increase in relaxin production