Survey
* Your assessment is very important for improving the work of artificial intelligence, which forms the content of this project
Download Reproductive ppt.
Transcript
Animal Reproduction & Development 2007-2008 Sexual & asexual reproduction Asexual offspring all have same genes (clones) Little to no variation Fragmentation and budding Sexual gametes (sperm & egg) fertilization mixing of genes variation 5/8/2017 Parthenogenesis Egg development without a male contribution Wasps, honeybees, aphids, komodo dragons, some fish, frogs and lizards Usually produces males 5/8/2017 Mechanisms of sexual reproduction Fertilization(union of sperm and egg) external internal Timing Compatible copulatory organs All species produce more offspring than the environment can handle Survival??? Pheromones chemical signals that influence the behavior of others (mate attractants) 5/8/2017 Reproductive hormones Testosterone from testes functions LH & FSH sperm production 2° sexual characteristics Estrogen from ovaries functions egg production prepare uterus for fertilized egg 2° sexual characteristics testes or ovaries 5/8/2017 Sex hormone control in males Hypothalamus GnRH Pituitary FSH & LH Testes testosterone Body cells 5/8/2017 Testicle (seminiferous tubules) Male reproductive system sperm spermatocytes Testes & epididymis sperm production & maturation Sperm production over 100 million produced per day! ~2.5 million released per drop! Glands seminal vesicles, prostate, bulbourethal produce seminal fluid = nutrient-rich (sugars) Spermatogenesis Epididymis Produce semen by age 7 Produce sperm by puberty (11-14 Testis Coiled seminiferous tubules Germ cell (diploid) 1° spermatocyte (diploid) MEIOSIS I 2° spermatocytes (haploid) MEIOSIS II Vas deferens Spermatids (haploid) Spermatozoa Cross-section of seminiferous tubule 5/8/2017 Female reproductiv e system 5/8/2017 Female reproductive system Ovaries Uterus tubes for eggs to travel from ovaries to uterus Cervix nurtures fetus; lining builds up each month Fallopian tubes produces eggs & hormones opening to uterus, dilates 10cm (4 inches) for birthing baby Vagina birth canal for birthing baby 5/8/2017 Menstrual cycle LH FSH Hypothalamus GnRH egg development ovulation = egg release corpus luteum Pituitary FSH & LH estrogen progesterone Ovaries lining of uterus estrogen Body cells 5/8/2017 days 0 7 14 21 28 Female hormones FSH & LH Estrogen release from pituitary stimulates egg development (follicle) & hormone release peak release = release of egg (ovulation) released from ovary cells around developing egg stimulates growth of lining of uterus lowered levels = menstruation Progesterone released from “corpus luteum” in ovaries cells that used to take care of developing egg stimulates blood supply to lining of uterus lowered levels = menstruation 5/8/2017 Egg maturation in ovary Corpus luteum produces progesterone to maintain uterine lining 5/8/2017 release Oogenesis Unequal meiotic divisions unequal distribution of cytoplasm 1 egg 2 polar bodies Cell stored in ovaries Meiosis 1 completed during egg maturation Cell matures in follicle on ovary Meiosis 2 completed triggered by fertilization ovulation Fertilization fertilization Cleavage Morula Blastocyst Implantation gastrulation neurulation Organogenesis Fetus Fertilization Joining of sperm & egg sperm head (nucleus) enters egg Acrosome (enzyme filled vesicle) Cleavage Repeated mitotic divisions of zygote 1st step to becoming multicellular unequal divisions establishes body plan different cells receive different portions of egg cytoplasm & therefore different regulatory signals Cleavage zygote morula blastula establishes future development zygote gastrulation morula blastula Gastrulation gastrulation in primitive chordates Establish 3 cell layers ectoderm outer body tissues skin, nails, teeth nerves, eyes, lining of mouth mesoderm middle ectoderm tissues blood & lymph, bone & notochord, muscle excretory & reproductive systems mesoderm endoderm inner lining digestive system lining of respiratory, excretory & reproductive systems endoderm Neurulation Formation of notochord & neural tube develop into nervous system Neural tube Notochord develops into vertebral column develops into CNS (brain & spinal cord) Organogenesis Organ development and differentiation from germ layers Placenta Materials exchange across membranes Human fetal development 4 weeks 7 weeks Human fetal development 10 weeks Human fetal development 12 weeks 20 weeks Human fetal development The fetus just spends much of the 2nd & 3rd trimesters just growing …and doing various flip-turns & kicks inside amniotic fluid Week 20 Human fetal development 24 weeks (6 months; 2nd trimester) fetus is covered with fine, downy hair called lanugo. Its skin is protected by a waxy material called vernix Human fetal development 30 weeks (7.5 months) umbilical cord Getting crowded in there!! 32 weeks (8 months) The fetus sleeps 9095% of the day & sometimes experiences REM sleep, an indication of dreaming Fetal slide notes Apoptosis Programmed cell death Sculpts body parts Genetically programmed elimination of tissues & cells that were used for only short periods in embryo or adult human embryos develop with webs between toes & fingers, but they are not born that way! 2004-2005 positive feedback Birth Birth (36 weeks) Intestine Placenta Umbilical cord Wall of uterus Bladder Cervix Vagina
