Think ahead How is gametogenesis different between males
Think ahead… § How is gametogenesis different between males and females? AP Biology
Sperm production Epididymis Testis Coiled seminiferous tubules germ cell (diploid) primary spermatocyte (diploid) MEIOSIS I secondary spermatocytes (haploid) Vas deferens spermatids (haploid) spermatozoa § Spermatogenesis continuous & prolific process Cross-section of seminiferous tubule u each ejaculation = 100 -600 million sperm AP Biology u MEIOSIS II
Spermatogenesis • Puberty until death! AP Biology
Egg production § Oogenesis u u eggs in ovaries halted before Anaphase 1 Meiosis 1 completed during maturation Meiosis 2 completed after fertilization unequal divisions 1 egg + 2 polar bodies Meiosis 1 completed during egg maturation What is the advantage of this development system? Meiosis 2 completed AP Biology triggered by fertilization ovulation
Gametogenesis – note the differences Spermatogensis Oogenesis AP Biology
Learning Check u AP Biology What is the function of gametogenesis? How are they different in males & females?
Male and Female Differences § Meiosis Males—produces four functional sperm u Females—produces one functional ovum and three polar bodies u § Sex cell size and structure Sperm are tiny, motile, and equipped with nutrients in seminal fluid u Egg is large, non-motile, and has nutrient reserves to nourish the embryo AP Biology until implantation u
Regulation: Reproductive hormones § Testosterone u u from testes functions LH & FSH § sperm production § 2° sexual characteristics § Estrogen u u from ovaries functions § egg production § prepare uterus for fertilized egg § 2° sexual characteristics AP Biology 2005 -2006 testes or ovaries
The female pattern § Estrous cycles/estrus (many § mammals) Menstrual Cycle (humans & primates) u Hormonal Cycle § Regulation of FSH & LH by the pituitary § Regulation of estrogen and progesterone by the ovaries u Ovarian cycles~ § Follicular phase ~ follicle growth § Ovulation ~ oocyte release § Luteal phase~ hormone release u Uterine Cycle § Menstruation AP Biology § Proliferative & Secretory Phases
LH Menstrual cycle FSH Hypothalamus Gn. RH egg development ovulation = egg release corpus luteum Pituitary FSH & LH estrogen progesterone Ovaries lining of uterus estrogen Body cells AP Biology 2005 -2006 days 0 7 14 21 28
Egg maturation in ovary Follicle maturation § under hormonal control one follicle matures § ~Days 1 -14 Ovulation § 10 -14 days after the onset of menstruation § one mature follicle will burst then release the secondary oocyte into fallopian tube Corpus luteum § produces progesterone to maintain uterine lining § Will remain through preg. if ovum is fertilized AP Biology
Ovulation Figure 16. 11 AP Biology
Menstruation & Ovulation § What factors can impact a woman’s § menstruation? At what point in the month is a woman most likely to get pregnant? (When is a woman most fertile? ) § Create a 28 day calendar with the hormonal, uterine, and ovarian events to help answer these questions u AP Biology P. 926 in the 5 th edition can help
Fertilization § § § AP Biology fertilization cleavage gastrulation neurulation organogenesis
Fertilization § Joining of sperm & egg u AP Biology sperm head (nucleus) enters egg
Cleavage § Repeated mitotic divisions of zygote 1 st step to becoming multicellular u unequal divisions establishes body plan u § different cells receive different portions of egg cytoplasm & therefore different regulatory signals AP Biology
Cleavage § zygote morula blastula u establishes future development zygote gastrulation AP Biology morula blastula
Gastrulation gastrulation in primitive chordates § Establish 3 cell layers u ectoderm § outer body tissues w skin, nails, teeth w nerves, eyes, lining of mouth u mesoderm ectoderm § middle tissues w blood & lymph, bone & notochord, mesoderm muscle w excretory & reproductive systems u endoderm § inner lining w digestive system w lining of respiratory, excretory & reproductive systems AP Biology protostome vs. deuterostome endoderm
Neurulation § Formation of notochord & neural tube u develop into nervous system Neural tube Notochord develops into vertebral column AP Biology develops into CNS (brain & spinal cord)
Organogenesis Mammalian embryo Umbilical blood vessels Chorion Bird embryo Amnion Yolk sac Allantois AP Biology Fetal blood vessels Placenta Maternal blood vessels
Placenta § Materials exchange across membranes AP Biology
Human fetal development 4 weeks AP Biology 7 weeks
Human fetal development 10 weeks AP Biology
Human fetal development 12 weeks AP Biology 20 weeks
Human fetal development § The fetus just spends much of the 2 nd & 3 rd trimesters just growing …and doing various flip-turns & kicks inside amniotic fluid Week AP Biology 20
Human fetal development § 24 weeks (6 months; 2 nd trimester) fetus is covered with fine, downy hair called lanugo. Its skin is protected by a waxy material called vernix AP Biology
Human fetal development § 30 weeks (7. 5 months) umbilical cord AP Biology
Getting crowded in there!! § 32 weeks (8 months) The fetus sleeps 90 -95% of the day & sometimes experiences REM sleep, an indication of dreaming AP Biology
positive feedback Birth AP Biology
Birth (36 weeks) Intestine Placenta Umbilical cord Wall of uterus Bladder AP Cervix Vagina Biology
Parturition § OXYTOCIN~ stimulates uterine contractions § 1 st stage: u u Opening up and thinning of the cervix. Ending in complete dilation. § 2 nd stage: u Expulsion of the baby as a result of strong uterine contractions. § 3 rd stage: u Expulsion of the placenta. § Lactation ~ prolactin & oxytocin AP Biology
The end of the journey! And you think 9 months of AP Bio is hard! AP Biology
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