Chapter 36: Reproduction and Development

Concept 36.1: Both asexual and sexual reproduction occur in the animal kingdom Asexual Reproduction 2

Sexual Reproduction: An Evolutionary Enigma Figure 36.3-3 Asexual reproduction Sexual reproduction Female Generation 1 Female Generation 2 Male Generation 3 Figure 36.3-3 The “reproductive handicap” of sex (step 3) Generation 4 3

(a) A. uniparens females (b) The sexual behavior of A. uniparens is Figure 36.5 Ovary size Ovulation Ovulation Progesterone Estradiol Hormone level Time Behavior Female Male- like Female Male- like Figure 36.5 Sexual behavior in parthenogenetic lizards (a) A. uniparens females (b) The sexual behavior of A. uniparens is correlated with the cycle of ovulation. 4

Variation in Patterns of Sexual Reproduction Finding a partner to mate with can be challenging. One solution is: Others can undergo: 5

External and Internal Fertilization External Fertilization Internal Fertilization 6

Concept 36.2: Reproductive organs produce and transport gametes Sexual reproduction in animals relies on sets of cells that are precursors for eggs and sperm 7

Variation in Reproductive Systems Many animals have gonads Some simple systems do not have gonads, but gametes form from undifferentiated tissue 8

Human Male Reproductive Anatomy http://www.youtube.com/watch?v=i93q0tKWX6g (Urinary bladder) Seminal vesicle (Urinary duct) (Rectum) (Pubic bone) Vas deferens Erectile tissue Ejaculatory duct Figure 36.8 Reproductive anatomy of the human male Urethra Prostate gland Penis Vas deferens Glans Bulbourethral gland Epididymis Testis Prepuce Scrotum Figure 36.8 9

Human Female Reproductive Anatomy Oviduct Ovary Uterus (Urinary bladder) (Pubic bone) (Rectum) (Urethra) Cervix Body Figure 36.9 Reproductive anatomy of the human female Glans Clitoris Vagina Prepuce Major vestibular gland Labia minora Labia majora Vaginal opening Figure 36.9 10

A Review of Meiosis: https://highered.mcgraw-hill.com/olcweb/cgi/pluginpop.cgi?it=swf::640::480::/sites/dl/free/0073532223/811364/How_Meiosis_Works.swf::How%20Meiosis%20Works Comparision of Meiosis and Mitosis: https://highered.mcgraw-hill.com/olcweb/cgi/pluginpop.cgi?it=swf::640::480::/sites/dl/free/0073532223/811364/Comparison_of_Meiosis_and_Mitosis.swf::Comparison%20of%20Meiosis%20and%20Mitosis

Gametogenesis in Males Figure 36.10a Gametogenesis in Males Epididymis Seminiferous tubule https://highered.mcgraw-hill.com/olcweb/cgi/pluginpop.cgi?it=swf::640::480::/sites/dl/free/0073532223/811364/Spermatogenesis.swf::Spermatogenesis Testis Primordial germ cell in embryo Cross section of seminiferous tubule Mitotic divisions Spermatogonial stem cell 2n Sertoli cell nucleus Mitotic divisions Spermatogonium 2n Mitotic divisions Primary spermatocyte 2n Meiosis I Figure 36.10a Exploring human gametogenesis (part 1: spermatogenesis) Secondary spermatocyte n n Lumen of seminiferous tubule Meiosis II Spermatids (two stages) Early spermatid n n n n Tail Neck Differentiation (Sertoli cells provide nutrients) Plasma membrane Midpiece Head Sperm cell n n n n Acrosome Nucleus Mitochondria 12

Gametogenesis in Females Ovary Primary oocyte within follicle Growing follicle In embryo Primordial germ cell Mitotic divisions Mature follicle 2n Oogonium Mitotic divisions Primary oocyte (present at birth), arrested in prophase of meiosis I 2n Ruptured follicle Completion of meiosis I and onset of meiosis II First polar body n n Secondary oocyte, arrested at metaphase of meiosis II Figure 36.10b Exploring human gametogenesis (part 2: oogenesis) Ovulated secondary oocyte Ovulation, sperm entry Completion of meiosis II Corpus luteum Second polar body n Fertilized egg n Degenerating corpus luteum 13

Concept 36.3: The interplay of tropic and sex hormones regulates reproduction in mammals Human reproduction is coordinated by hormones from the hypothalamus, anterior pituitary, and gonads Hypothalamus secretes: Which, in turn, causes the anterior pituitary to secrete: 14

Hormonal Control of the Male System Hypothalamus GnRH Anterior pituitary FSH LH Negative feedback Negative feedback Sertoli cells Leydig cells Figure 36.12 Hormonal control of the testes Inhibin Spermatogenesis Testosterone Testis Figure 36.12 15

Hormonal Control of the Female System Control by hypothalamus Inhibited by combination of estradiol and progesterone https://highered.mcgraw-hill.com/olcweb/cgi/pluginpop.cgi?it=swf::640::480::/sites/dl/free/0073532223/811364/positive_and_negative_feedback.swf::Positive%20and%20Negative%20Feedback Hypothalamus Stimulated by high levels of estradiol 1 GnRH Anterior pituitary Inhibited by low levels of estradiol 2 FSH LH (b) Pituitary gonadotropins in blood 6 LH FSH 3 FSH and LH stimulate follicle to grow LH surge triggers ovulation (c) Ovarian cycle 7 8 http://www.youtube.com/watch?v=WGJsrGmWeKE (3D animation) Growing follicle Corpus luteum Maturing follicle Degenerating corpus luteum Follicular phase Ovulation Luteal phase Estradiol secreted by growing follicle in increasing amounts Progesterone and estradiol secreted by corpus luteum 4 (d) Ovarian hormones in blood Peak causes LH surge (see ) 5 6 Figure 36.13 The reproductive cycles of the human female 10 Estradiol 9 Progesterone Estradiol level very low Progesterone and estra- diol promote thickening of endometrium (e) Uterine (menstrual) cycle Endometrium Figure 36.13 Menstrual flow phase Proliferative phase Secretory phase Days 5 10 14 15 20 25 28 16

Control by hypothalamus Inhibited by combination of Figure 36.13a (a) Control by hypothalamus Inhibited by combination of estradiol and progesterone Hypothalamus Stimulated by high levels of estradiol 1 GnRH Anterior pituitary Inhibited by low levels of estradiol 2 FSH LH (b) Pituitary gonadotropins in blood 6 Figure 36.13a The reproductive cycles of the human female (part 1: FSH and LH levels) LH FSH FSH and LH stimulate follicle to grow LH surge triggers ovulation 3 Days 5 10 14 15 20 25 28 17

Corpus luteum Degenerating corpus luteum Maturing follicle Figure 36.13b (b) Pituitary gonadotropins in blood 6 LH FSH 3 FSH and LH stimulate follicle to grow LH surge triggers ovulation (c) Ovarian cycle 7 8 Figure 36.13b The reproductive cycles of the human female (part 2: ovarian cycle) Corpus luteum Degenerating corpus luteum Growing follicle Maturing follicle Follicular phase Ovulation Luteal phase Estradiol secreted by growing follicle in increasing amounts Progesterone and estradiol secreted by corpus luteum 4 Days 5 10 14 15 20 25 28 18

Corpus luteum Degenerating corpus luteum Maturing follicle Figure 36.13c (c) Ovarian cycle 7 8 Corpus luteum Degenerating corpus luteum Growing follicle Maturing follicle Follicular phase Ovulation Luteal phase Estradiol secreted by growing follicle in increasing amounts Progesterone and estradiol secreted by corpus luteum 4 (d) Ovarian hormones in blood Peak causes LH surge (see ) 6 5 Figure 36.13c The reproductive cycles of the human female (part 3: ovarian hormone levels) 10 9 Estradiol Progesterone Estradiol level very low Progesterone and estra- diol promote thickening of endometrium Days 5 10 14 15 20 25 28 19

Progesterone and estra- diol promote thickening of endometrium Figure 36.13d (d) Ovarian hormones in blood Peak causes LH surge (see ) 6 5 10 9 Estradiol Progesterone Estradiol level very low Progesterone and estra- diol promote thickening of endometrium (e) Uterine (menstrual) cycle Endometrium Figure 36.13d The reproductive cycles of the human female (part 4: menstrual cycle) Menstrual flow phase Proliferative phase Secretory phase Days 5 10 14 15 20 25 28 20

Uterine/Menstrual Cycle Ovarian Cycle Uterine/Menstrual Cycle

Menopause- What Is It? After about ______cycles, human females undergo menopause, which is defined as Menopause is very unusual among animals 22

Menstrual Versus Estrous Cycles 23

Concept 36.4: Fertilization, cleavage, and gastrulation initiate embryonic development Across animal species, embryonic development involves common stages occurring in a set order Fertilzation Animation: http://www.youtube.com/watch?v=_5OvgQW6FG4 24

EMBRYONIC DEVELOPMENT Sperm Zygote Figure 36.14 EMBRYONIC DEVELOPMENT Sperm Zygote Adult frog Egg FERTILIZATION CLEAVAGE Metamorphosis Blastula GASTRULATION Figure 36.14 Developmental events in the life cycle of a frog ORGANO- GENESIS Larval stages Gastrula Tail-bud embryo 25

Sperm plasma membrane Sperm nucleus Acrosomal process Basal body Figure 35.15-5 Sperm plasma membrane Sperm nucleus Acrosomal process Basal body (centriole) Actin filament Sperm head Cortical granule Fused plasma membranes Figure 36.15-5 The acrosomal and cortical reactions during sea urchin fertilization (step 5) Acrosome Perivitelline space Hydrolytic enzymes Jelly coat Fertilization envelope Vitelline layer Sperm- binding receptors Egg plasma membrane 26

Acrosomal reaction: plasma membrane Figure 36.16 1 2 3 4 6 8 10 20 30 40 50 5 60 90 Binding of sperm to egg Acrosomal reaction: plasma membrane depolarization (fast block to polyspermy) Seconds Increased intracellular calcium level Cortical reaction (slow block to polyspermy) Formation of fertilization envelope complete Figure 36.16 Timeline for the fertilization of sea urchin eggs Increased protein synthesis Minutes Fusion of egg and sperm nuclei complete Onset of DNA synthesis First cell division 27

Cleavage and Gastrulation 50 m (a) Fertilized egg (b) Four-cell stage (c) Early blastula (d) Later blastula Figure 36.17 Cleavage in an echinoderm embryo Figure 36.17 28

Digestive tube (endoderm) Anus (from blastopore) Figure 36.18 Animal pole Blastocoel Mesenchyme cells Vegetal plate Vegetal pole Blastocoel Filopodia Archenteron Mesenchyme cells Blastopore Figure 36.18 Gastrulation in a sea urchin embryo 50 m Key Blastocoel Future ectoderm Ectoderm Future mesoderm Archenteron Future endoderm Mouth Blastopore Mesenchyme (mesoderm forms future skeleton) Digestive tube (endoderm) Anus (from blastopore) 29

ECTODERM (outer layer of embryo) Figure 36.19 ECTODERM (outer layer of embryo) Epidermis of skin and its derivatives (including sweat glands, hair follicles) Nervous and sensory systems Pituitary gland, adrenal medulla Jaws and teeth Germ cells MESODERM (middle layer of embryo) Skeletal and muscular systems Circulatory and lymphatic systems Excretory and reproductive systems (except germ cells) Dermis of skin Adrenal cortex Figure 36.19 Major derivatives of the three embryonic germ layers in vertebrates ENDODERM (inner layer of embryo) Epithelial lining of digestive tract and associated organs (liver, pancreas) Epithelial lining of respiratory, excretory, and reproductive tracts and ducts Thymus, thyroid, and parathyroid glands 30

Human Conception, Embryonic Development, and Birth Conception occurs in: The resulting zygote begins cleavage about ____ hours after fertilization and produces a blastocyst after ____ more days A few days later, the embryo implants into the endometrium of the uterus Gestation is: 31

(a) From ovulation to implantation Figure 36.20 3 Cleavage 4 Cleavage continues. Ovary 2 Fertilization Uterus 5 Implantation 1 Ovulation Endometrium (a) From ovulation to implantation Figure 36.20 Formation of a human zygote and early postfertilization events Endometrium Inner cell mass Cavity Trophoblast Blastocyst (b) Implantation of blastocyst https://highered.mcgraw-hill.com/olcweb/cgi/pluginpop.cgi?it=swf::640::480::/sites/dl/free/0073532223/811365/FolliclOocyteMature.swf::Maturation%20of%20the%20Follicle%20and%20Oocyte 32