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SEXUAL REPRODUCTION AND DEVELOPMENT SEXUAL REPRODUCTION INCREASES THE GENETIC VARIATION WITHIN A SPECIES Sexual Development & Puberty For the first 6 weeks of development, human male and female embryos are identical in appearance. Then, during the 7th week major changes occur because of either testosterone or estrogen. Puberty is a period of rapid growth and sexual maturation during which the reproductive system becomes fully functional. The onset of puberty varies, but may occur between the ages of 9 and 15 (generally about one year earlier in females.) MALE REPRODUCTIVE SYSTEM TESTES: SITE FOR SPERM CELL PRODUCTION (GAMETES) – remain outside the body – the steroid hormone testosterone is produced here SEMINIFEROUS TUBULES: where sperm are produced EPIDIDYMIS: sperm fully mature here and are stored PROSTATE GLAND: SEMINAL FLUID IS MADE (activates sperm cells) VAS DEFERENS: CONNECTS MALE REPRO SYSTEM WITH URETHRA VASECTOMY URETHRA: URINE and SEMEN EMPTY INTO IT Male Reproductive System Section 39-3 Urinary bladder Pubic bone Vas deferens Urethra Penis Large intestine Rectum Seminal vesicle Prostate gland Scrotum Bulbourethral gland Epididymis Testis Image from Prentice Hall Resource Pro, 2002 Sperm Cell nucleus neck mitochondria tail The nucleus is found in the head of the sperm cell and the mitochondria in the midpiece. Secondary Sex Characteristics in Males Growth of facial and body hair Increase in body size Deepening of the voice FEMALE REPRODUCTIVE SYSTEM FOLLICLE: Clusters of cells surrounding a single egg. The follicle helps to mature the egg. OVULATION: Release of a mature egg (ovum) from the Ovary into the Fallopian Tube (oviduct.) UTERUS: organ where embryo grows. CERVIX: outer end of uterus VAGINA: canal that leads outside the body FEMALE REPRODUCTIVE SYSTEM FERTILIZATION: FUSION OF SPERM & EGG NUCLEI. FERTILIZATION OCCURS IN OVIDUCT. Fertilized egg forms a zygote, then a morula (a ball of about 50 cells) and then a blastocyst (hollow ball of cells) which implants itself in the wall of the uterus. (Placenta will begin to form.) Gastrulation occurs to create three germ layers. Female Reproductive System Section 39-3 Fallopian tube Fallopian tube Ovary Urinary bladder Ovary Uterus Pubic bone Urethra Cervix Vagina Rectum Vagina Image from Prentice Hall Resource Pro, 2002 Menstrual Cycle Image from Prentice Hall Resource Pro, 2002 The Menstrual Cycle Interaction of endocrine system and reproductive system. Takes an average of about 28 days. An egg develops and is released from the ovary and the uterus prepares to receive a fertilized egg. Consists of 4 phases: follicular phase, ovulation, luteal phase & menstruation. Follicular Phase Begins when estrogen levels are low in blood. FSH and LH are secreted and travel to ovaries where they cause a follicle to develop to maturity. Generally a single follicle will develop, but sometimes 2 or 3 mature during the same cycle. (TWINS) As the follicle develops, it produces increased amounts of estrogen which cause the uterine lining to thicken in preparation for receiving the fertilized egg. Ovulation The shortest phase of the cycle. Occurs about midway through the cycle and lasts 3-4 days. A rush of FSH and LH cause the follicle to rupture and the mature egg is released into one of the fallopian tubes. Luteal Phase The cells of the ruptured follicle undergo a change and turn yellow – and is now known as the corpus luteum. The corpus luteum continues to release estrogen and also begins to release progesterone (which are hormones that stimulate cell growth and tissue development in the lining of the uterus.) Great chance of fertilization during the first 2 days of this phase. Menstruation If fertilization does not occur, the egg will pass through the uterus without implanting itself. The corpus luteum will begin to disintegrate and less and less estrogen & progesterone are released. When estrogen levels fall below a certain point, the lining of the uterus begins to detach from the uterine wall – tissue, blood and the unfertilized egg are discharged through the vagina. The flow lasts about 3-7 days. MENSTRUAL CYCLE PITUITARY GLAND FSH LH (LEUTIUM) OVARY GROWTH OF FOLLICLE ESTROGEN UTERUS WALLS BUILD UP NEG. FEEDBACK SHUTS OFF FSH OVULATION (EGG RELEASED) CORPUS LUTEUM GROWS PROGESTERONE MAINTAINS UTERINE WALLS FOR PREGNANCY What causes Menstruation to occur? Decreasing estrogen levels of Secondary Sex Characteristics in Females Development of the reproductive system Widening of the hips Development of the breasts EMBRYOLOGY FERTILIZATION: fusion of gametes GASTRULATION: formation of gastrula FERTILIZATION SPERM NUCLEUS FUSES WITH EGG NUCLEUS. 46 CHROMOSOMES IN EACH BODY CELL OF HUMAN. (DIPLOID # = 46) SOMETIMES CALLED (2n) GAMETES HAVE MONOPLOID a.k.a. HAPLOID # = 23 FERTILIZATION: + SPERM N = 23 EGG N = 23 ZYGOTE 2N = 46 MONOPLOID + MONOPLOID = DIPLOID Fertilization and Implantation Fallopian tube Day 2 Day 3 Day 1 Day 4 4 cells Morula Day 7 Blastocyst Zygote 2 cells Fertilization Day 0 Implantation of blastocyst Uterine wall Ovary Egg released by ovary Image from Prentice Hall Resource Pro, 2002 DIVISION OF ZYGOTE MITOSIS 2 CELLS 4 CELLS ZYGOTE mitosis: cell division cleavage: MITOSIS (CELL DIVISION) OF THE ZYGOTE MANY TIMES TO CREATE A BALL OF CELLS MORULLA SOLID BALL OF CELLS FORMED BY THE PROCESS CALLED CLEAVAGE..... SOME CELLS ARE LARGER THAN OTHERS MORULLA TURNS INTO A BLASTULA BLASTULA: HOLLOW BALL OF CELLS FLUID SECRETED INTO THE CENTER OF THE MORULLA, PUSHES CELLS OUTWARD TO FORM A BLASTULA BLASTULA TO GASTRULA BLASTOCYST CELLS PINCH INWARD A.K.A. GASTRULA INVAGINATION GASTRULA CONTINUES TO INVAGINATE NOTE: THREE LAYERS OF CELLS ARE FORMED. THIS IS CALLED DIFFERENTIATION MESODERM: MIDDLE LAYER FORMS ECTODERM OUTER ENDODERM INNER ECTODERM: BECOMES EPIDERMIS (SKIN) & NERVES ENDODERM: BECOMES DIGESTIVE GLANDS INCLUDING PANCREAS, LIVER. ALSO EXCRETORY & RESPIRATORY SYSTEM MESODERM: BECOMES THE REST PREGNANCY PLACENTA DEVELOPS BECAUSE BLASTOCYST ATTACHES PLACENTA KEEPS CORPUS LUTEUM DEVELOPED CORPUS LUTEUM MAINTAINS UTERUS & STOPS FSH NO PREGNANCY? NO PLACENTA FORMS CORPUS LUTEUM SHRIVELS UP NO PROGESTERONE IS MADE UTERINE WALLS BREAK DOWN (MENSTRUATION) “FLOW PHASE” FSH STARTS UP AGAIN Internal Development and the Placenta Amniotic sac Placenta Umbilical cord Fetal portion of placenta Maternal portion of placenta Villus in chorion Uterus Amnion Amnion Umbilical cord Maternal artery Umbilical arteries Maternal vein Umbilical vein Image from Prentice Hall Resource Pro, 2002 PLACENTAL MAMMALS DEVELOP IN THE UTERUS UTERUS MATERNAL PLACENTA UMBILICAL CHORD FETUS FETAL PLACENTA AMNIOTIC FLUID *FETAL & MATERNAL PLACENTA ARE SEPARATE. EVERYTHING MOVES BY DIFFUSION AND OSMOSIS CHORION CERVIX MITOSIS: PROCESS TO MAKE NORMAL BODY CELLS (SOMATIC CELLS) START WITH 46 CHROMOSOMES REPLICATE THOSE CHROMOSOMES DIVIDE THE CELL SO THAT EACH CELL GETS 46 CHROMOSOMES 2 DAUGHTER CELLS PARENT CELL 46 46 DIPLOID DIPLOID 92 DOUBLE 46 DIPLOID MEIOSIS PROCESS BY WHICH GAMETES ARE PRODUCED DIPLOID CELLS DIVIDE TO BECOME MONOPLOID CELLS MEIOSIS: PROCESS BY WHICH GAMETOGENESIS OCCURS START WITH THE DIPLOID # (46) END UP WITH MONOPLOID/HAPLOID # (23) 46 92 FROM 1 CELL YOU GET 4 CELLS 46 46 23 REPLICATE CHROMOSOMES 23 23 23 GAMETOGENESIS PROCESS BY WHICH GAMETES ARE MADE HUMAN MALES: OCCURS IN TESTES THROUGHOUT LIFE (SPERMATOGENESIS) HUMAN FEMALES: OCCURS IN OVARIES BEFORE BIRTH (OOGENESIS) PROCESS INVOLVES: TAKING THE DIPLOID # OF CHROMOSOMES (46) AND MAKING A CELL WITH MONOPLOID/HAPLOID # (23) FERTILIZATION COMBINES 2 GAMETES TO CREATE A ZYGOTE. EACH MONOPLOID GAMETE CONTAINS 1/2 THE CHROMOSOME NUMBER....OFTEN CALLED (N) NUMBER. N # gamete + N# gamete monoploid + monoploid BECAUSE OF FERTILIZATION, THE ZYGOTE WILL HAVE THE DIPLOID NUMBER OF CHROMOSOMES.... CALLED THE (2N) NUMBER. 2N# zygote diploid SPERMATOGENESIS OOGENESIS FIRST POLAR BODY FIRST MEIOTIC DIVISION SECOND MEIOTIC DIVISION 4 SPERM CELLS ARE PRODUCED SECOND POLAR BODIES. THESE DISINTIGRATE. OVUM ONLY ONE OVUM REACHES MATURITY. IN THE CYTOPLASM THERE IS MUCH MORE FOOD FOR THE EMBRYO (YOLK). MITOSIS CREATES 2 DIPLOID CELLS ALL SOMATIC CELLS DIVIDE BY MITOSIS ONE CELLULAR DIVISION P-M-A-T ASEXUAL REPRO METAPHASE CHROMOSOMES LINE UP UNDERNEATH EACH OTHER NO INTERKINESIS MEIOSIS CREATES 4 HAPLOID CELLS CELLS IN GONADS REPRODUCE BY MEIOSIS TO MAKE GAMETES 2 CELLULAR DIVISIONS P-M-A-T SEXUAL REPRO METAPHASE I: CHROMOSOMES LINE UP IN PAIRS (TETRADSYNAPSE) INTERKINESIS MITOSIS - MEIOSIS SIMILARITIES AT THE BEGINNING THEY REPLICATE DNA IN THE S STAGE OF INTERPHASE ALL PHASES ARE SIMILAR EXCEPT METAPHASE I OF MEIOSIS Early Years Infancy: 4 weeks after birth until about 2 years old – marked by rapid growth and development. Childhood: period between infancy and puberty – language is acquired and motor coordination is perfected. Adolescence: surge in sex hormones starts and growth spurts occur (long bone growth). Adulthood: physical strength and development peak and then systems begin to show slight declines in efficiency (menopause in women.) Birth Control Methods http://www.fda.gov/Fdac/features/1997/babytabl.html