Human Reproduction & Development AP Biology 2005-2006 Reproductive hormones Testosterone from testes functions LH & FSH sperm production Secondary sex characteristics Estrogen from ovaries functions egg production prepare uterus for fertilized egg Secondary sex characteristics AP Biology testes or ovaries 2005-2006 Gametogenesis Occurs in the gonads (ovaries and testes) Meiosis that results in the production of gametes (haploid cells) from germ cells (diploid cells) Spermatogenesis and Oogenesis AP Biology Slide 2 of 18 2005-2006 Spermatogenesis Occurs in the testes in the seminiferous tubules —results in the production of 4 sperm Mature in the epididymis and gain mobility Produced immediately after puberty AP Biology Slide 6 of 18 2005-2006 Spermatogenesis Epididymis 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 AP Biology 2005-2006 Spermatogenesis The sperm contains lots of mitochondris (powerhouse of the cell) —why? AP Biology The sperm have a long journey they need a lot of energy (hence the need for lots of mitochondria) 2005-2006 Male reproductive system Sperm production over 100 million produced per day! AP Biology ~2.5 million released per drop! 2005-2006 Male reproductive system Testicles produces sperm and hormones Scrotum sac that holds testicles outside of body Epididymis where sperm mature Vas deferens tubes for sperm to travel from testes to penis Glands nutrient rich fluid to feed and protect sperm buffer to counteract acids in vagina AP Biology 2005-2006 Male reproductive system AP Biology 2005-2006 Pathway of Semen epididymis (testes) vas deferens urethra A vasectomy is a procedure in which the vas deferens is cut so that the man will no longer be able to father children. AP Biology 2005-2006 Female reproductive system AP Biology 2005-2006 Oogenesis unequal division of cytoplasm Allows for more nutrition to be available to the egg in case fertilization occurs. AP Biology Slide 5 of 18 2005-2006 Female reproductive system Ovaries produces egg and hormones Uterus Nourishes fetus; lining builds up each month Fallopian tubes tubes for eggs to travel from ovaries to uterus Cervix opening to uterus, dilates 10cm (4 inches) for birthing baby Vagina Birth canal for birthing baby AP Biology 2005-2006 Female Reproductive System ovaries – where oogenesis takes place oviduct (Fallopian Tube) – where fertilization takes place uterus – where the embryo grows and develops vagina – birth canal AP Biology Slide 12 of 18 2005-2006 Female reproductive system AP Biology 2005-2006 Female Reproductive Hormones LH and FSH act on the ovaries and cause them to produce progesterone and estrogen AP Biology 2005-2006 Slide 13 of 18 Female Menstrual Cycle Each month, a woman’s body prepares for the possible fertilization of an egg Ovarian cycle = an egg matures and is released Uterine cycle = the endometrium (lining) of the uterus thickens (becomes ready to have a fertilized egg implant) then breaks down (if no fertilization occurs). AP Biology Slide 14 of 18 2005-2006 Female Menstrual Cycle ovulation – release of egg from ovary triggered by a surge of LH. AP Biology Slide 15 of 18 2005-2006 Female Menstrual Cycle Day 1 = first day of a woman’s period Hormonal control is complicated! During different times of the cycle, estrogen can either stimulate or inhibit other hormones AP Biology 2005-2006 Slide 17 of 18 Female Menstrual Cycle If fertilization occurs, the embryo secretes HcG which maintains the lining of the uterus hCG is what is tested for in pregnancy tests Birth control pills are synthetic progesterone and estrogen that “trick” the body into thinking the woman is pregnant – no ovulation occurs AP Biology 2005-2006 Fertilization AP Biology 2005-2006 Fertilization Joining of sperm & egg AP Biology sperm head enters egg 2005-2006 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 AP Biology 2005-2006 Cleavage zygote morula blastula AP Biology establishes future development 2005-2006 Gastrulation Establish 3 cell layers ectoderm outer layers skin, nails, teeth, ectoderm nerves mesoderm mesoderm blood, bone & muscle endoderm inner lining digestive system AP Biology endoderm 2005-2006 Placenta Materials exchange across membranes AP Biology 2005-2006 Human fetal development 4 weeks AP Biology 7 weeks 2005-2006 Human fetal development 10 weeks AP Biology 2005-2006 Human fetal development 12 weeks AP Biology 20 weeks 2005-2006 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 AP Biology 2005-2006 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 AP Biology 2005-2006 Human fetal development 30 weeks (7.5 months) umbilical cord AP Biology 2005-2006 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 2005-2006 Hormone induction positive feedback AP Biology Birth 2005-2006 Birth (36 weeks) Intestine Placenta Umbilical cord Wall of uterus Bladder AP Cervix Vagina Biology 2005-2006 The end of the journey! AP Biology 2005-2006