Objectives To analyze the hormones which affect the

Objectives • To analyze the hormones which affect the reproductive system of animals. • To examine the major parts and functions of the female and male reproductive system. • To discover the process of the fertilization of two gametes. 2

Main Menu Basic Reproduction Endocrinology Female Reproductive System Estrous Cycle Male Reproductive System Transport & Survival of Gametes Fertilization 3

Reproduction • Is a series of physiological and psychological events which must be properly timed • Is either asexual or sexual 5

Asexual Reproduction • Involves one parent • Lacks variation as the offspring tend to have the same genotype and phenotype • For example, flatworms can be divided into two halves and each half grows into a separate organism Genotype – physical appearance of an organism Phenotype – the physical characteristics of an organism, determined by both the genetic makeup and environmental influences 6

Sexual Reproduction • Requires two parents or the fusion of two gametes • Involves the production of sperm and eggs – some are produced by the same individual – some are produced by different individuals • Promotes variation as offspring inherit genes from two different parents • Fertilization can be either internal or external Gametes – a reproductive cell, either a sperm or egg, capable of fusing with a gamete of the opposite sex to produce a fertilized egg 7

Internal Fertilization • Is practiced by animals which lay shelled eggs or have a period of embryonic development • Enables land animals to reproduce as it allows sperm to swim to the egg and prevents the sperm and eggs from drying out • Have a copulatory organ, or penis, in males for transferring sperm Fun Fact: The sexes of vertebrates are separate but some vertebrates can change sex, normally in fish. 8

External Fertilization • Used by animals living in aquatic environments – animal sperm must swim to eggs – protects the gametes from drying out • Requires the gametes to be released into the water at the same time and place 9

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Hormones • • Are chemical messengers Are produced by glands Are carried by the bloodstream to an organ Cause physiological change Fun Fact: A newly mated female mouse will abort if placed with a male which is not the previous mate. 11

Hormone Producing Glands • Include the following types: – endocrine glands secrete hormones into the bloodstream – exocrine glands secrete hormones externally through ducts, not into the bloodstream 12

Hormones • Are produced from the following: – anterior pituitary – ovary – testes – placenta – uterus – adrenal gland 13

Hormones from the Anterior Pituitary • Include the following: – follicle stimulating hormone – luteinizing hormone – human menopausal gonadotropin – prolactin 14

Follicle Stimulating Hormone (FSH) • Actions in the female include stimulating: – follicle growth – estrogen production – inhibin production is a feedback hormone which turns off FSH 15

Follicle Stimulating Hormone (FSH) • Actions in the male include stimulating: – spermiogenesis or sperm production – inhibin production – androgen-binding protein • Uses by males include stimulating: – follicular development to induce multiple ovulations – for example, super ovulating cows Androgen-binding protein – binds to testosterone and aids in spermiogensis 16

Luteinizing Hormone (LH) • Actions in female include: – maturation of follicle – stimulates ovulation – corpus luteum (CL) formation – progesterone production 17

Luteinizing Hormone (LH) • Stimulates testosterone production in males • Synthesizes androgen in males • Is used to treat cystic ovaries 18

Human Menopausal Gonadotropins (h. MG) • Is recovered from the urine of menopausal women • Contains both LH and FSH units • Is used to superovulate animals 19

Prolactin (Prl) • Actions in the female include: – milk synthesis or the making of milk in the mammary gland – development of the mammary gland – maternal behavior 20

Hormones from the Ovary • Include the following: – estrogens – progestins or progestogens – inhibin – relaxin 21

Estrogens • Are produced in theca and granulosa cells of a follicle • Actions include: – estrus – uterine contractions to bring the sperm up the uterus – duct growth of mammary gland – secondary sex characteristics – growth of the female reproductive tract 22

Estrogens • Uses include: – initiation of behavioral estrus in female to collect sperm from male – initiation of uterine contractions – promotes the growth of domestic animals • i. e. , growth implants – birth control for humans 23

Progestins or Progestogens • Is produced in the luteal cells of the corpus luteum • Actions include: – maintenance of pregnancy – reduces uterine contractions to cause the uterus to stay still and allow the embryo to develop – reduces estrus – growth of mammary glands – secondary sex characteristics – growth of reproductive tract 24

Progestins or Progestogens • Actions include: – preventing abortion – birth control in humans – synchronizing estrus and ovulation 25

Inhibin • Is produced in the granulosa cells of the follicle • Is found in the follicular fluid of the follicle • Suppresses the release of FSH – as the follicle is growing in size, more inhibin is produced to reduce the amount of FSH produced because the follicle does not need as much FSH 26

Relaxin • Is produced by the following during pregnancy: – luteal cells of the corpus luteum – placenta – uterus 27

Relaxin • Actions include: – relaxation of pelvic ligaments – softens the connective tissue in the uterine muscles – softens the connective tissue of the cervix at parturition 28

Hormones from the Testes • Include the following: – testosterone – inhibin 29

Testosterone • Is produced in the leydig cells (gonads) • Actions include: – spermatocytogenesis – male sexual behavior or libido – secondary sex characteristics – maintains accessory sex organs 30

Testosterone • Uses include: – prepare teaser animals for estrus detection – improvement of feedlot animal performance 31

Inhibin • Is produced by the sertoli cells • Suppresses the release of FSH 32

Hormones from the Placenta • Include the following: – estrogens: same as the ovary – progestins: same as the ovary – relaxin: same as the ovary – human chorionic gonadotropin – pregnant mare serum gonadotropin – placental lactogen 33

Human Chorionic Gonadotropin (h. CG) • Actions include: – converts the corpus luteum of the menstrual cycle to the corpus luteum of the pregnancy – is LH-like as it induces ovulation 34

Human Chorionic Gonadotropin (h. CG) • Uses by man include: – human pregnancy tests – induces ovulation – treats cystic ovaries • Is obtained from the urine of pregnant women 35

Pregnant Mare Serum Gonadotropin (PMSG or ECG) • Is produced in the mare’s placenta • Actions include: – formation of corpus luteum in mare during pregnancy – is FSH-like in domestic animals other than the mare • Is isolated from a mare’s serum • Stimulates follicular development in animals other than the mare 36

Placental Lactogen • Is highest during the last trimester of pregnancy • Is produced in the placenta • Actions include: – development of mammary gland for milk production – regulation of maternal nutrients to fetus – regulation of fetal growth 37

Hormones from the Uterus • Include the following: – relaxin: same as the ovary – prostaglandin F 2α – prostaglandin E 2 38

Prostaglandin F 2 a (PGF 2 a) • Is produced in the uterus in the female • Is produced in vesicular glands of the male • Actions include: – the regression of the corpus luteum – causes the restriction of blood vessels – promotes smooth muscle contraction in the uterus for sperm transport, ovum transport, parturition and ovulation – promotes gonadotropin release 39

Prostaglandin E 2 (PGE 2) • Is produced in the uterus in the female • Is produced in vesicular glands of the male • Actions include: – promotes the growth of the corpus luteum – involved in the process of ovulation – involved in the process of gamete transport 40

Hormones from the Adrenal Gland • Includes Cortisol • Is produced in the adrenal cortex • Actions include: – start of parturition – interacts with prolactin to start making milk – reduces inflammation 41

Hormones which Affect the Anterior Pituitary • Gonadotropin releasing hormone – causes the release of FSH and LH from anterior pituitary • Prolactin releasing factor – releases prolactin from the anterior pituitary in small amounts until just before and after parturition 42

Oxytocin (OT) • Affects the posterior pituitary • Is produced in the hypothalamus • Is produced in the corpus luteum of the cow, ewe and human • Is stored in the posterior pituitary 43

Oxytocin (OT) • Functions include: – milk let-down – promotes uterine muscle contractions during sperm and egg transport and parturition – lysis the corpus luteum in the cow, goat and ewe Lysis – is the destruction of cells 44

Oxytocin (OT) • Functions include: – stimulates milk let-down – passing out of retained placenta – aids in delivery when labor is extended 45

Melatonin • Is produced in the pineal gland • Release is controlled by the length of day – is produced at night as light hitting the retina of the eye sends a message to the pineal gland to lower melatonin synthesis – controls seasonal breeders in response to the length of day – short day breeders include sheep – long day breeders include some rodents, horses and cats 46

Hormonal Feedback Systems • Include the following: – negative feedback • one hormone inhibits the release of another hormone • i. e. , increasing concentrations of inhibin slows FSH release from the anterior pituitary – positive feedback • one hormone stimulates the release of another hormone • i. e. , increasing concentrations of estrogens stimulates the release of Gn. RH, LH, FSH and prolactin 47

ASSESSMENT 48

Assessment 1. Which of the following is NOT an action of FSH? A. Follicle growth B. Estrogen production C. Stimulates ovulation D. Spermiogenesis 2. Which of the following is an action of LH? A. Maturation of follicle B. Spermiogenesis C. Androgen-binding protein D. Estrogen production 49

Assessment 3. Which of the following is a hormone from the testes? A. Testosterone B. Estrogen C. Inhibin D. Both A and C 4. Which of the following is NOT an action of oxytocin? A. Controls seasonal breeders in response to the length of day B. Milk let-down C. Promotes uterine muscle contractions during sperm and egg transport and parturition D. Lysis the corpus luteum in the cow, goat and ewe 50

Assessment 5. An action of inhibin is to suppress the release of FSH. A. True B. False 51

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Female Reproductive System • Functions of the reproductive tract include: – transports sperm – produces oocytes, the female gamete – aids in fertilization of sperm and egg – provides environment for fetus – gives birth to fetus – provides nutrients to young 53

External Genitalia • Includes the following: – vestibule: a common pathway for reproductive and urinary systems – clitoris: has same embryonic origin as the male penis – labia (vulva): protects and produces mucous for lubrication to aid in sperm transport 54

Vagina • Functions include the following: – site of copulation – site of semen disposition – absorbs the seminal plasma – is a part of the birth canal and dilates during parturition – canal for urinary system Copulation – the act of procreation between a male and female 55

Cervix • Functions include the following: – site of semen deposition in the mare and sow – is a reservoir for sperm as it is a favorable environment for sperm to survive for three to four days – is closed during pregnancy to block bacterial invasion – is part of the birth canal 56

Uterus • Functions include the following: – fetus development – hormone production 57

Uterus • Types of uteri include the following: – duplex – bicornuate – bipartite – simplex 58

Duplex Uterus • Is found in the rat, mouse, rabbit and guinea pig • Has two cervices • Has no uterine body • Uterine horns are completely separate 59

Bicornuate Uterus • Is found in litter bearing animals such as pigs and dogs • Has one cervix • Has very small uterine body • Uterine horns are long and convoluted Convoluted – has many overlapping coils or folds 60

Bipartite Uterus • • • Is found in the cow, ewe and mare Has one cervix Has small uterine body in cow and ewe Has large uterine body in mare Uterine horns are separated by the septum in the cow and ewe 61

Simplex Uterus • • Is found in primates including humans Has one cervix Has a very large prominent uterine body Has no uterine horns 62

Layers of the Uterine Wall • Include the following – endometrium – myometrium – perimetrium 63

Endometrium • Is the inner layer • Is the site of placental attachment • Contains glands which provide secretions for the development of the embryo 64

Myometrium • Is the middle, muscular layer • Is responsible for uterine contractions which move sperm toward the oviducts • Is responsible for uterine contractions which push the fetus towards the cervix during parturition 65

Perimetrium • Is the outer layer • Blocks adhesions 66

Oviduct • Is also known as uterine or fallopian tubes • Is a paired structure connecting the ovary with the uterus • Functions include the following: – transports the sperm and ova – is the site of fertilization – is the site of early cell divisions of the embryo 67

Oviduct • Structures include the following: – Utero-Tubal Junction (UTJ): where uterine horn meets the oviduct – isthmus: second half of oviduct – Ampullary-Isthmic Junction (AIJ): Site of fertilization – ampulla: first half of oviduct – infundibulum: funnel shaped, covers the ovary to pick up ovum (not in mare) – fimbria: petal-like structure which contain ciliated cells to move the ovum 68

Ovaries • Are a paired structure • Functions include the following: – produces estrogens and progesterone – contains female gametes 69

Ovaries • Structures include the following: – outside surface which contains the surface epithelium and connective tissue – cortex which is the outer portion which contains all the eggs except in the mare – medulla which is the inner portion which contains all the blood and nerves except in the mare 70

Ovaries • Functional structures include the following: – follicles – oocytes – corpus luteum 71

Follicles • Stages include the following: – primary follicle: the stage of the majority of the follicles – secondary follicle: growing in size – tertiary or Graafian follicle: the follicle right before ovulation • many in litter bearers such as dogs and cats • only one in cows and horses • Are fluid filled with liquor folliculi 72

Follicles • Cell layers include the following: – theca externa: the outside of the follicle – theca interna: the inside of the follicle – granulosa cells: are in the basement membrane – cumulus oophorus: contains the egg which is surrounded by granulosa cells – corona radiata: the nurse cells of the egg 73

Oocytes • Is the female gamete • Have a limited number – is highest before birth – decrease continually until depleted 74

Corpus Luteum (CL) • Forms from the corpus hemorrhagicum • Is composed of luteal cells – transformed granulosa and theca cells • Produces progesterone • Is called corpus albicans after regression Corpus hemorrhagicum – is the site of collapsed follicle which contains a blood clot in ovary 75

ASSESSMENT 76

Assessment 1. In the female tract, the ______ is the site of copulation. A. Uterus B. Vagina C. Ovary D. Fallopian tube 2. Which type of uterus is found in litter-bearing animals? A. Unicornuate B. Bicornuate C. Arcuate D. Didelphic 77

Assessment 3. In which part of the female tract is the fetus developed? A. Uterus B. Vagina C. Ovary D. Fallopian tube 4. Which type of follicle is the follicle right before ovulation? A. Primary follicle B. Graafian follicle C. Tertiary follicle D. Both B and C 78

Assessment 5. What hormone does the CL produce? A. Testosterone B. Estrogen C. Progesterone D. Oxytocin 79

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The Estrous Cycle • Is a reoccurring set of behavioral and physical changes from one period of estrus to the next estrus which occur in mammalian females • Estrus, also known as heat, is a period of sexual receptivity in mammalian females (except humans) • Estrous is an adjective describing the action cycle • Estrus is a noun describing standing heat 81

The Estrous Cycle • Phases include the following: – proestrus – metestrus – diestrus 82

Proestrus • • Is part of the follicular phase Occurs on days 17 -20 or -4 to -1 in a cow Is the phase just before estrus Is when the ovarian follicles are growing rapidly • Causes an increase in estrogen from growing follicles • Causes a decrease in progesterone from the corpus luteum 83

Estrus • • Is part of the follicular phase Is day one or the day of standing heat Is the period of sexual receptivity Causes surges of FSH and LH and triggers ovulation • Causes ovulation in the sow, ewe and mare 84

Metestrus • Is part of the luteal phase • Is days two to four in a cow • Is when the Graafian follicle has ovulated and estrogen levels decrease • Is when the corpus luteum is forming from the corpus hemorrhagicum • Causes an increase in progesterone levels • Begins preparing the uterus for the embryo if pregnant 85

Diestrus • • Is part of the luteal phase Is days 5 -16 in a cow Is absent in animals with short cycles Is when the corpus luteum becomes fully developed • Slows follicular development, ovulation and estrus due to high progesterone levels 86

Diestrus • If pregnant: – embryo signals the uterus of its presence causing the corpus luteum not to regress – progesterone is still released • If no embryo is present: – the uterus releases PGF 2α which causes the corpus luteum to regress – there is a decrease in progesterone – the Graafian follicle(s) begins final development • The cycle starts over again with proestrus 87

Anestrus • Is the period between diestrus and proestrus • Is NOT a phase of the estrous cycle • Is a period of sexual inactivity between two periods of estrus • Is the nonbreeding season of the ewe, mare and cat • Varies in length • Is characterized by the quiescence of the reproductive tract • Ends when proestrus begins 88

Types of Estrous Cycles • Include the following: – continuous estrus – monoestrous cycle – polyestrus cycle 89

Continuous Estrus • Occurs in rabbits and other induced ovulators • Mating induces LH release • Ovulation occurs 8 to 12 hours after mating 90

Monestrous Cycle • Occurs in bears, wolves, foxes and some dogs • Have only one estrous cycle per year • Is separated by a long anestrous period between each cycle 91

Polyestrous Cycle • Can be either a true or seasonal polyestrous cycle – true polyestrous cycle • has two or more estrous cycles per year unless interrupted by pregnancy composed of proestrus, metestrus and diestrus merging into proestrus – seasonal polyestrous • is the same except the last diestrus of breeding season would proceed into anestrus 92

Types of Ovulation • Include the following: – spontaneous ovulation – induced ovulation 93

Spontaneous Ovulation • Is repeated ovulation at regular intervals except during pregnancy • Release of LH is cyclic and does not require mating stimulus • Release of LH is prompted by increasing concentrations of estrogens • Occurs in the cow, sow, ewe, mare, rat, hamster and guinea pig 94

Induced Ovulation • Is ovulation which occurs after stimulation of vagina and/or cervix • Release of LH occurs only after mating stimulus • Continues estrus for a variable length of time • Occurs in rabbit, cat, mink and llama 95

Estrous Cycles Estrous Cycle Length of Estrus Time of ovulation Ewe Sow Cow Mare 16 -17 days 19 -21 days 20 -22 days 19 -25 days 24 -36 hours after the onset of estrus 48 -72 hours 35 -45 hours after the onset of estrus 18 -24 hours 10 -11 hours after the end of estrus 4 -7 days 1 -2 days before the end of estrus Estrous Cycle Length of Estrus Time of ovulation Bitch 75 days 9 days 2 days after the onset of estrus Queen 9 -18 days if no ovulation 3 -16 days Induced ovulation Mouse 5 days 6 -10 hours 3 -5 hours after the onset of estrus 96

Follicular Phase of the Estrous Cycle • Is part of the cycle when follicles are maturing • Is when estrous behavior occurs 97

Follicular Phase • Has an increase in granulosa cell numbers • Has growth of thecal cells which surround the outside of the follicle – theca externa: connective tissue surrounding the entire follicle – theca interna: inner layer • Has rapid maturation of follicles just before estrus 98

Luteal Phase of the Estrous Cycle • Occurs when the granulosa and theca cell differentiate into luteal cells • Corpus Luteum reaches maximum size • Corpus Luteum regresses to become a corpus albicans 99

Follicular Changes During Ovulation • Include the following: – blood flow increases and fluid builds up – increase in production of histamine and prostaglandins – proteolytic enzymes are produced and collagen in follicular wall starts to break down – basement membrane breaks down and capillaries contact granulosa cells – follicular cells stop producing estrogen – finally pressure builds up against weakened follicle wall and rupture occurs 100

Oogenesis • Begins in prenatal period • Is the formation and maturations of the female gamete – the potential gamete in a primary follicle is referred to as an oogonium – mitotic division of the oogonia yields primary oocytes Mitosis: cell division in which the nucleus divides 101

Oogenesis 102

Oogenesis • Ceases before birth – the number of potential oocytes is fixed and starts decreasing at birth – oocytes become arrested • Maturation continues after puberty – some oocytes start maturing during each cycle – the others remain in an arrested state 103

Process of Oogenesis • The first step includes: – growth of the oocyte – cytoplasm enlargement – zona pellucida development – increase of follicular cells Zona pellucida: the thick, outer membrane of the oocyte 104

Process of Oogenesis • The second step includes: – meiosis • primary oocyte → secondary oocyte – is completed just before ovulation in the cow, sow, ewe and mare 105

Process of Oogenesis • The third step – begins immediately after first meiosis – is not completes unless fertilization has taken place – includes meiosis • secondary oocyte + sperm → zygote 106

Ovulation • Occurs 24 to 45 hours after the surge of LH except for the mare • Occurs in the mare before peak of LH surge • Process includes the following: – LH stimulates the enzymes in the follicular wall and maturation of the oocyte – PGF 2α stimulates follicle rupture – the enzymes cause the follicular wall to weaken, then the follicle ruptures and follicular fluid escapes the ovum 107

ASSESSMENT 108

Assessment 1. _______, also known as heat, is the period of sexual receptivity in mammalian females. A. Estrus B. Anestrus C. Parturition D. Monoestrous 2. Which of the following is NOT one of the four phases of the estrous cycle? A. Preoestrus B. Monoestrous C. Metestrus D. Diestrus 109

Assessment 3. _______ is characterized by the quiescence of the reproductive tract. A. Estrus B. Anestrus C. Parturition D. Monoestrous 4. Which type of estrous cycle requires mating to induce LH release? A. Continuous estrus B. Monoestrous cycle C. Polyestrus D. All of the above 110

Assessment 5. Oogenesis begins in the female in the post-natal period. A. True B. False 111

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Male Reproductive System • Functions include the following: – to produce and maintain a supply of sperm – to detect females in estrus – to inseminate females and fertilize the female gamete 113

Scrotum • Functions include the following: – to support the testes – to control temperature – protection 114

Scrotum • Is a two-lobed sac • Is homologous the labia majora in the female • Contain two layers: – thick skin which contains large sweat and sebaceous glands – smooth muscles which cause it to shrink or expand in relation to temperature 115

Spermatic Cord • Is a paired structure • Functions include the following: – carries nerves and blood supply to testes – carry sperm to urethra – controls temperature • Contains internal and external cremaster muscles which control the proximity to the body 116

Testes • Is a paired structure • Functions include the following: – to produce sperm – to produce testosterone • Is housed in the scrotum • Is covered with tunica vaginalis • Has an outer connective tissue layer referred to as the tunica albuginea 117

Epididymis • Is a paired structure • Functions include the following: – sperm concentration – storage of sperm – sperm maturation – transport of spermatozoa • Sperm is mature and motile by the time the sperm leaves 118

Epididymis • Is divided into three parts – caput epididymis (head): closest to the testes – corpus epididymis (body) – cauda epididymis (tail): contains very concentrated sperm • Consists of a single convoluted tube 119

Ductus Deferens • Is a paired structure • Is also known as the vas deferens • Transports sperm during ejaculation 120

Urethra • Is a single structure • Transports sperm and urine • Structure includes: – pelvic urethra: part of the pelvic area – penile urethra: part or tube inside the penis 121

Accessory Glands • Contribute to the fluid volume and content of semen • Are located along the pelvic urethra • Include the following: – vesicular glands – prostate gland – bulbourethral glands 122

Vesicular Glands • Are also known as seminal vesicles • Secrete the following: – fructose and sorbitol for energy – phosphate and carbonate buffers to protect against shifts in p. H • Secrete gelatinous material in seminal plasma in the stallion 123

Prostate Gland • Secretes the following nutrients into semen: – sodium – calcium – chlorine – magnesium – zinc • Cleanses the urethra in the stallion 124

Bulbourethral Glands • Is also known as Cowper’s gland • Is located along the pelvic urethra at the junction between the pelvic and penile urethra • Is a source of gel-like material in boar semen • Flushes urine residue from the penile urethra • Contributes to the seminal plasma in the stallion 125

Penis • Is an organ of copulation • Is jointly used by the reproductive and urinary systems • Is located at the base of the pelvic urethra 126

Prepuce • Is also known as the sheath • Encloses the free end of the penis • Is homologous to the labia minora in the female 127

Cryptorchidism • Is the lack of the testes descent into the scrotum • Prevents thermoregulation • Common in stallions and boars 128

Spermatogenesis • • Is the process by which sperm is formed Occurs in the seminiferous tubules Begins at puberty Is a continuous process throughout the life of a male 129

Spermatogenesis 130

Spermatogenesis • Is divided into two parts: – spermatocytogenesis: a series of divisions from spermatogonia to spermatids – spermiogenesis: spermatids undergo metamorphosis to form spermatozoa Metamorphosis – a transformation 131

Spermatocytogenesis • Occurs in seminiferous tubules which have germ and sertoli cells • Germ cells include the following types: – spermatogonia – primary spermatocytes – secondary spermatocytes – spermatids – spermatozoa 132

Spermatocytogenesis • Is a mitotic division of dormant spermatogonium into active spermatogonium – active spermatogonium divides mitotically four times resulting in 16 primary spermatocytes – dormant spermatogonium divides later to repeat the process above – each primary spermatocyte goes through meiotic division to result in 32 secondary spermatocytes – each secondary spermatocyte completes meiosis by dividing to form 64 spermatids 133

Spermiogenesis • Spermatids undergo changes to form spermatozoa – the sperm head is formed – acquires a cap called acrosome – the cell elongates to form a tail • Spermatogenesis is complete when spermatozoa are released by Sertoli cells 134

Semen • Is seminal plasma plus sperm • Functions of seminal plasma includes: – providing a vehicle for sperm – buffering so sperm will survive – providing energy for sperm 135

Semen Anatomy • Does not grow or divide • Lacks cytoplasm • Contains a head and tail 136

Sperm Head • Includes the following: – a nucleus which contains DNA – an acrosome which conatins enzymes needed for fertilization 137

Sperm Tail • Includes the following: – mid piece which is the power house for energy – main piece which is the propellant machinery – end piece which is the short terminal portion 138

Sperm Motility • Is not necessary for transport in male or female tracts • Is useful for breeding soundness evaluations • Is useful for evaluating sperm for Artificial Insemination • Plays important role in encounter with female gametes 139

Sperm Capacitation • Is the third maturation process of spermatozoa • Occurs only in the female tract • Is a process which sperm must go through for penetration of the zona pellucida 140

ASSESSMENT 141

Assessment 1. In the male tract, the _____________ contribute to the fluid volume and content of semen. A. Testicles B. Sebaceous glands C. Accessory glands D. Testosterone 2. Which part of the male reproductive system produces testosterone? A. Scrotum B. Testes C. Spermatic cord D. Epididymis 142

Assessment 3. Which of the following is the lack of the testes descent into the scrotum? A. Cryptochidism B. Copulation C. Mitosis D. Metamorphosis 4. Which of the following begins at puberty for the male? A. Spermatogenesis B. Spermatocytogenesis C. Cryptorchidism D. Metamorphosis 143

Assessment 5. Sperm capacitation takes place in the female tract. A. True B. False 144

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Sperm Transport • Includes the journey through both the male and female tract • Through the female tract includes: – cervix – uterus – oviduct 146

Sperm Transport Through the Cervix • Functions include the following: – is a barrier and reservoir – capacitation of sperm – is a filtration for sperm 147

Sperm Transport Through the Uterus • Functions include the following: – is a barrier and reservoir – has uterine contractions to move the sperm up the tract – contractions are stimulated by oxytocin and estrogen 148

Sperm Transport Through the Oviduct • Functions include the following: – is a barrier and reservoir – has contractions to move sperm and ovum – opens and closes uterotubal junction – cilia moves fluid 149

Ovum Transport • Is moved by the following: – cilia – smooth muscle contractions • Is fertilized at the ampullary-isthmic junction 150

Fate of Unfertilized Ovum • Is fragmented into cytoplasmic segments of unequal size • Disappears by phagocytosis 151

ASSESSMENT 152

Assessment 1. Sperm is NOT transported through which part of the female tract? A. Cervix B. Uterus C. Oviduct D. Bladder 2. Sperm is transported through both the female and male reproductive tracts. A. True B. False 153

Assessment 3. Which of the following is NOT a function of the cervix? A. Acts as a barrier and reservoir B. Capacitates the sperm C. Contracts the uterus to move the sperm up the tract D. Filters the sperm 4. The cervix, uterus and oviduct share which of the following? A. Capacitates the sperm B. Spermatocytogenesis C. Acting as a barrier and reservoir D. Has contractions to move the sperm and ovum 154

Assessment 5. Unfertilized ovum disappears by phagocytosis. A. True B. False 155

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Fertilization • Is the fusion of two cells to form one single cell known as the zygote • Occurs in the ampullary-isthmic junction 157

The Fertilization Process • The sperm binds to receptors in the zona pellucida • The bound sperm completes an acrosome reaction in preparation for the penetration of the zona pellucida • The ovum releases a variety of enzymes so the sperm can penetrate the zona pellucida • The sperm head attaches to the vitelline membrane 158

The Fertilization Process • The zona pellucida recognizes the attachment and blocks other sperm form attaching to the vitelline membrane • The sperm penetrates the vitelline membrane into the cytoplasm and the tail separates • The duration of fertilization varies from 12 to 24 hours 159

Syngamy • Is the union of pronuclei or when chromosomes mix • Is when the process of fertilization is complete • Is when the zygote has been formed 160

ASSESSMENT 161

Assessment 1. Fertilization is which of the following? A. The genetic makeup of an organism B. The fusion of two cells to form one single cell known as the zygote C. A chemical substance in the body which regulates or controls specific physiological processes D. The act of procreation between a male and female 2. The sperm binds to receptors in which of the following? A. Zona pellucida B. Ovum C. Oviduct D. Vitelline membrane 162

Assessment 3. The duration of fertilization various from 48 to 72 hours. A. True B. False 4. Which of the following is when the process of fertilization is complete? A. Lysis B. Spermatocytogenesis C. Syngamy D. Mitosis 163

Assessment 5. The sperm penetrates which of the following into the cytoplasm and the tail separates? A. Zona pellucida B. Ovum C. Oviduct D. Vitelline membrane 164

FINAL ASSESSMENT 165

Final Assessment 1. Sexual reproduction requires the production of sperm and eggs. A. True B. False 2. Which hormone causes ovulation? A. Testosterone B. Estrogen C. LH D. Oxytocin 166

Final Assessment 3. Which of the following is responsible for secondary sex characteristics in the female? A. Relaxin B. Inhibin C. Estrogen D. Testosterone 4. Which of the following causes the CL to regress? A. e. CG B. PGF 2α C. Placental lactogen D. Oxytocin 167

Final Assessment 5. The function of melatonin is to control seasonal breeders in response to the length of day. A. True B. False 6. Which of the following is a layer of the uterine wall? A. Endometrium B. Myometrium C. Perimetrium D. All of the above 168

Final Assessment 7. In the female tract, the utero-tubal junction is the site of fertilization. A. True B. False 8. The ___________ is a reoccurring set of behavioral and physical changes from one period of estrus to the next estrus which occurs in mammalian females. A. Polyestrus B. Estrous cycle C. Continuous estrus D. Monoestrous cycle 169

Final Assessment 9. Sperm is produced in the scrotum. A. True B. False 10. Which of the following is the FIRST step of the fertilization process? A. The ovum releases a variety of enzymes so the sperm can penetrate the zona pellucida B. The sperm head attaches to the vitelline membrane C. The sperm binds to receptors in the zona pellucida D. The sperm penetrates the vitelline membrane into the cytoplasm and the tail separates 170

Acknowledgements • Estrous Cycle (2008). Texas Tech University. Retrieved June 18, 2014 from http: //www. ttuhsc. edu/som/obgyn/documents/estouscycle. pdf • External vs. Internal Fertilization (n. d. ). Cornell University. Retrieved June 18, 2014 from http: //www. biog 1445. org/demo/08/fertilization. html • Gametogenesis (n. d. ). Human Embryology. Retrieved June 18, 2014 from http: //www. embryology. ch/anglais/cgametogen/oogenese 02. ht ml • Learning Reproduction in Farm Animals • http: //animalsciences. missouri. edu/reprod/Notes/index. htm 171

Acknowledgements Production Coordinator Taylor Hurst Graphic Designer Melody Rowell Technical Writer Jessica Odom V. P. of Brand Management Clayton Franklin © MMXIV CEV Multimedia, Ltd. Executive Producer Gordon W. Davis, Ph. D. 172