1. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Animal Reproduction (continued from 11/24/08)

2. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings External fertilization Eggs

3. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Reproductive anatomy of the human female Glans (Rectum) Cervix Vagina Bartholin’s gland Vaginal opening Ovary Oviduct Labia majora Labia minora (Urinary bladder) (Pubic bone) Uterus Urethra Shaft Prepuce Clitoris

4. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Vagina Uterus Cervix Ovaries Oviduct Uterine wall Endometrium Follicles Corpus luteum

5. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Reproductive anatomy of the human male Erectile tissue of penis Prostate gland (Urinary bladder) Bulbourethral gland Vas deferens Epididymis Testis Seminal vesicle (behind bladder) Urethra Scrotum Glans penis

6. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Seminal vesicle (Rectum) Vas deferens Ejaculatory duct Prostate gland Bulbourethral gland (Urinary bladder) (Pubic bone) Erectile tissue of penis Urethra Glans penis Prepuce Vas deferens Epididymis Testis Scrotum

7. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Human Oogenesis Ovary Primary germ cell in embryo Differentiation Oogonium in ovary Mitotic division Primary oocyte, arrested in prophase of meiosis I (present at birth) Completion of meiosis I and onset of meiosis II Primary oocyte within follicle Secondary oocyte, arrested at meta- phase of meiosis II First polar body Ovulation Entry of sperm triggers completion of meiosis II Ovum Growing follicle Mature follicle Ruptured follicle Ovulated secondary oocyte Corpus luteum Degenerating corpus luteum 2n2n 2n2n n n n n Second polar body

8. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Epididymis Seminiferous tubule Testis Cross section of seminiferous tubule Sertoli cell nucleus Lumen of Seminiferous tubule Spermatogonium Primary spermatocyte (in prophase of meiosis I) Secondary spermatocyte Early spermatids Spermatids (at two stages of differentiation) Differentiation (Sertoli cells provide nutrients) Meiosis II Meiosis I completed Mitotic division, producing large numbers of spermatogonia Sperm cells Acrosome Nucleus Mitochondria Neck Tail Plasma membrane HeadMidpiece 2n2n 2n2n n n n nnn n n n n Differentiation and Onset of meiosis I Human Spermatogenesis

9. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Placental circulation Placenta Umbilical cord Chorionic villus containing fetal capillaries Maternal blood pools Uterus Fetal arteriole Fetal venule Umbilical cord Maternal portion of placenta Fetal portion of placenta (chorion) Umbilical arteries Umbilical vein Maternal arteries Maternal veins

10. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Human fetal development 5 weeks. Limb buds, eyes, the heart, the liver, and rudiments of all other organs have started to develop in the embryo, which is only about 1 cm long. (a) 14 weeks. Growth and development of the offspring, now called a fetus, continue during the second trimester. This fetus is about 6 cm long. (b) 20 weeks. By the end of the second trimester (at 24 weeks), the fetus grows to about 30 cm in length. (c)

11. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings A model for the induction of labor EstrogenOxytocin from ovaries from fetus and mother's posterior pituitary Induces oxytocin receptors on uterus Stimulates uterus to contract Stimulates placenta to make Prostaglandins Stimulate more contractions of uterus Positive feedback

12. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Animal Development

13. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Early events of fertilization in mammals The sperm migrates through the coat of follicle cells and binds to receptor molecules in the zona pellucida of the egg. (Receptor molecules are not shown here.) 1 This binding induces the acrosomal reaction, in which the sperm releases hydrolytic enzymes into the zona pellucida. 2 Breakdown of the zona pellucida by these enzymes allows the sperm to reach the plasma membrane of the egg. Membrane proteins of the sperm bind to receptors on the egg membrane, and the two membranes fuse. 3 The nucleus and other components of the sperm cell enter the egg. 4 Enzymes released during the cortical reaction harden the zona pellucida, which now functions as a block to polyspermy. 5 Sperm nucleus Acrosomal vesicle Egg plasma membrane Zone pellucida Sperm basal body Cortical granules Follicle cell EGG CYTOPLASM

14. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Cleavage in an echinoderm embryo Fertilized egg. Shown here is the zygote shortly before the first cleavage division, surrounded by the fertilization envelope. The nucleus is visible in the center. (a) Four-cell stage. Remnants of the mitotic spindle can be seen between the two cells that have just completed the second cleavage division. (b)Morula. After further cleavage divisions, the embryo is a multicellular ball that is still surrounded by the fertilization envelope. The blastocoel cavity has begun to form. (c) Blastula. A single layer of cells surrounds a large blastocoel cavity. Although not visible here, the fertilization envelope is still present; the embryo will soon hatch from it and begin swimming. (d)

15. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings SURFACE VIEW CROSS SECTION Animal pole Blastocoel Dorsal lip of blastopore Dorsal lip of blastopore Vegetal pole Blastula Blastocoel shrinking Archenteron Blastocoel remnant Ectoderm Mesoderm Endoderm Gastrula Yolk plug Key Future ectoderm Future mesoderm Future endoderm Gastrulation begins when a small indented crease, the dorsal lip of the blastopore, appears on one side of the blastula. The crease is formed by cells changing shape and pushing inward from the surface (invagination). Additional cells then roll inward over the dorsal lip (involution) and move into the interior, where they will form endoderm and mesoderm. Meanwhile, cells of the animal pole, the future ectoderm, change shape and begin spreading over the outer surface. The blastopore lip grows on both sides of the embryo, as more cells invaginate. When the sides of the lip meet, the blastopore forms a circle that becomes smaller as ectoderm spreads downward over the surface. Internally, continued involution expands the endoderm and mesoderm, and the archenteron begins to form; as a result, the blastocoel becomes smaller. 1 2 3 Late in gastrulation, the endoderm-lined archenteron has completely replaced the blastocoel and the three germ layers are in place. The circular blastopore surrounds a plug of yolk-filled cells. Gastrulation in a frog embryo

16. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Organogenesis in a chick embryo Neural tube Notochord Archenteron Lateral fold Form extraembryonic membranes YOLK Yolk stalk Somite Coelom Endoderm Mesoderm Ectoderm Yolk sac Eye Forebrain Heart Blood vessels Somites Neural tube Early organogenesis. The archenteron forms when lateral folds pinch the embryo away from the yolk. The embryo remains open to the yolk, attached by the yolk stalk, about midway along its length, as shown in this cross section. The notochord, neural tube, and somites subsequently form much as they do in the frog. (a) Late organogenesis. Rudiments of most major organs have already formed in this chick embryo, which is about 56 hours old and about 2–3 mm long (LM). (b)

17. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Adult derivatives of the three embryonic germ layers in vertebrates ECTODERMMESODERMENDODERM Epidermis of skin and its derivatives (including sweat glands, hair follicles) Epithelial lining of mouth and rectum Sense receptors in epidermis Cornea and lens of eye Nervous system Adrenal medulla Tooth enamel Epithelium or pineal and pituitary glands Notochord Skeletal system Muscular system Muscular layer of stomach, intestine, etc. Excretory system Circulatory and lymphatic systems Reproductive system (except germ cells) Dermis of skin Lining of body cavity Adrenal cortex Epithelial lining of digestive tract Epithelial lining of respiratory system Lining of urethra, urinary bladder, and reproductive system Liver Pancreas Thymus Thyroid and parathyroid glands

18. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Nervous System

19. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Overview of information processing by nervous systems Sensor Effector Motor output Integration Sensory input Peripheral nervous system (PNS) Central nervous system (CNS)

20. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Structure of a vertebrate neuron Dendrites Cell body Nucleus Axon hillock Axon Signal direction Synapse Myelin sheath Synaptic terminals Presynaptic cell Postsynaptic cell

21. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Astrocytes 50 µm

22. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Schwann cells and the myelin sheath Myelin sheath Nodes of Ranvier Schwann cell Schwann cell Nucleus of Schwann cell Axon Layers of myelin Node of Ranvier 0.1 µm Axon

23. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings A chemical synapse Presynaptic cell Postsynaptic cell Synaptic vesicles containing neurotransmitter Presynaptic membrane Postsynaptic membrane Voltage-gated Ca 2+ channel Synaptic cleft Ligand-gated ion channels Na + K+K+ Ligand- gated ion channel Postsynaptic membrane Neuro- transmitter 1 Ca 2+ 2 3 4 5 6

24. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Major Neurotransmitters

25. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings The vertebrate nervous system Central nervous system (CNS) Peripheral nervous system (PNS) Brain Spinal cord Cranial nerves Ganglia outside CNS Spinal nerves

26. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Ventricles, gray matter, and white matter Gray matter White matter Ventricles

27. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Body representations in the primary motor and primary somatosensory cortices Tongue Jaw Lips Face Eye Brow Neck Thumb Fingers Hand Wrist Forearm Elbow Shoulder Trunk Hip Knee Primary motor cortex Abdominal organs Pharynx Tongue Teeth Gums Jaw Lips Face Nose Eye Fingers Hand Forearm Elbow Upper arm Trunk Hip Leg Thumb Neck Head Genitalia Primary somatosensory cortex Toes Parietal lobeFrontal lobe