Transcript PowerPoint
Human Reproduction Reproductive Systems Many similarities between species Most similar within order Basics of initial sperm & egg production, copulation, fertilization the same. Male Reproductive Anatomy Testes—Sperm & testosterone Seminiferous tubules— Sperm production Epididymis—Sperm storage & maturing Vas deferens—Moves sperm from dpididymis Urethra—Moves sperm & urine outside of body Scrotum—Skin sac that contains testes Penis—Male copulatory organ Male Reproductive Anatomy Seminal vesicles—Nutrient fluid Prostate gland—Alkaline fluid, prolongs sperm lifespan in female Bulbourethral glands— Lubricating fluid Semen—combination of sperm & glandular fluids Spermatogenesis Begins at 12-14 years old Continues through entire life Under hormonal control Gonadotropin-releasing hormone (GnRH)—stimulates other hormones to be released; produced by hypothalamus Follicle-stimulating hormone (FSH)—enhances spermatogenesis, not fully understood; anterior pituitary Lutenizing hormone (LH)—controls testosterone release; anterior pituitary Testosterone—Sexual characteristics & behavior, sperm production Inhibin—Released when high sperm count, suppresses other hormones, therefore sperm production. Spermatogenesis Occurs in seminiferous tubules in testes Spermatogonia cells Leydig cells—release testosterone Germ cells undergo meiosis 1 diploid (2n) 4 haploid (n) cells Sertoli cells—release inhibin Spermatogenesis Most flagellated (including some plants) Nematodes—amoeboid Head Nucleus—contains genetic material Acrosome—enzymes to penetrate egg Midpiece Mitochondria Tail Female Reproductive Anatomy Ovaries—produce ovum, reproductive hormones Oviducts (Fallopian tubes)—moves ovary to uterus, fertilization Uterus—houses embryo Endometrium—lining of uterus, supports developing fetus Cervix—opening to uterus Vagina—birth canal, copulatory organ Oogenesis Begins before birth Continues until menopause Eggs develop to primary oocyte, stopping in prophase I At puberty, oocyte develops into primary follicle Develops to metaphase II and stops (secondary oocyte) Secondary oocyte released during ovulation Remaining follicle becomes corpus luteum, secretes progesterone Secondary oocyte only develops further if fertilized Oogenesis Numerous hormones! GnRH—triggers release of LH and FSH; hypothalamus FSH—stimulates primary oocytes to develop to next stage; anterior pituitary LH—stimulates ovulation, estrogen production; anterior pituitary Estrogen—female reproductive tract development, sex characteristics; ovary, corpus luteum Progesterone—maintains endometrium; corpus luteum Menstrual Cycle Mestruation—Day 1-5 Low estrogen & progesterone Follicular Phase—Day 6-13 Estrogen increases Endometrium thickens Ovulation—Day 14 LH & FSH released just prior Mature egg released Luteal Phase—Day 15-28 Corpus luteum increases progesterone Endometrium thickness doubles If no pregnancy, CL degenerates Fertilization 150-350 million sperm deposited Only a few hundred reach oviduct Acrosome dissolves outer coating of egg (zona pellucida) Sperm penetrates to egg cell membrane Sperm nucleus enters egg Fertilization Once sperm penetrates zona pellucida, cortical granules are released, and move into zona pellucida Zona pellucida hardens, becoming impermeable to any more sperm Embryo Development Conceptus—First 2 weeks Embryo—3rd through 8th weeks Fetus—After 8 weeks Gestation averages 38 weeks (266 days) Rabbits—31 days Dogs & Cats—63 days Horses—335-340 days Bottlenose Dolphins—364-378 days Elephants—630-660 days (22 months) Embryo Development Zygote—fertilized egg, diploid Undergoes cleavage (mitosis) multiple times Travels down oviduct Morula—solid ball of cells Embryo Development Morula develops into blastula Blastocoel—fluid-filled center Implants in endometrium in later stages Some cells of blastula migrate inside This is where embryo will form Is now a gastrula Ectoderm, endoderm, mesoderm form Embryo Development Week 4 Notochord forms Primitive heart tube forms Week 5 Heart develops, begins to beat Limb buds form Earliest stages of organs Week 6 Blood begins flowing Hands and feet developing Week 8 Nipples & hair follicles form Limb movements noticeable Fetal Development Weeks 10-13 Face well formed Tooth buds appear Fetus able to make a fist Genitals well differentiated Weeks 14-17 Sucking motions with mouth Lanugo (fine hair) begins to form Week 20 Eyebrows, eyelashes, nails develop Fetal heartbeat heard with stethoscope Mother feels fetus move Lanugo hair covers body Fetal Development Week 24 All eye structures developed Fingerprints forming Alveoli forming Responds to sounds Week 28 Respiratory system can exchange gasses Brain growing rapidly Nervous system controlling body functions Premature birth high risk, but possible Opens & closes eyes Week 32 Rhythmic breathing Thalamic connections in brain Bones fully developed Fetal Development Weeks 37-40 Considered full term