1. Pregnancy, Development, and Lactation

2. Fertilization _______________: (act of breeding) intromission, thrusting, and ejaculation Copulation triggers _________ release from posterior pituitary gland of the female Oxytocin causes contraction of smooth muscle of the female reproductive organs Semen is usually deposited in the upper portion of the __________ Spermatozoa transported by swimming, by contractions of uterus and oviducts, and by action of cilia in oviducts

3. Capacitation Series of changes spermatozoa undergo in the female reproductive tract to increase their chance of fertilization 1. Change in ion movements (influx of Ca ++ ) through the cell membrane 2. Increase in cells' metabolic rate 3. Increase in rate of sugar usage for energy 4. Release of digestive enzymes from _____________ Help spermatozoa penetrate layers around ovum to accomplish fertilization

4. Fertilization Large number of spermatozoa locate and swarm around ovum in _____________ Some begin tunneling through layers surrounding ovum Aided by digestive enzymes in acrosome Once a single spermatozoon penetrates cell membrane of ovum, the membrane blocks other sperm from entering

5. Zygote ____________ — a newly fertilized ovum. Male and female ___________ join together ____________ — a newly fertilized ovum. Male and female ___________ join together Male pronucleus: nucleus of the fertilizing spermatozoon Male pronucleus: nucleus of the fertilizing spermatozoon Female pronucleus: nucleus of the ovum Female pronucleus: nucleus of the ovum Each pronucleus contains the haploid chromosome number Each pronucleus contains the haploid chromosome number Fertilization restores the ___________ chromosome number Fertilization restores the ___________ chromosome number

6. Cleavage: Zygote to Blastocyst Rapid division of zygote (~1 division/day) Overall size of zygote does not change __________: solid mass of cells; stage after zygote __________: hollow ball of cells with a mass of cells on one side (future embryo); stage after morula; will implant in uterus

7. Implantation While cleavage is taking place, the zygote is slowly moving from the oviduct to the ___________ propelled by muscular contractions and cilia Enzymes produced by the blastocyst dissolve away a small pit in the endometrium, where the blastocyst will attach In _____________ species, the multiple blastocysts randomly space along the horns and body of the uterus ____________ begins to form as soon as the blastocyst implants in the uterus

8. Placenta Multilayered, fluid-filled, membranous sac that surrounds the fetus and links it to the blood supply of the uterus Outermost layer of placenta attaches to ________ _________ Fetal and maternal blood vessels are in close proximity to each other in this area Site of exchange of blood, nutrients, and wastes No direct contact between fetal and maternal blood occurs Connected to the fetus via the _________ ______ Umbilical ________: carries oxygen-rich blood to fetus Umbilical ________: carry deoxygenated blood back to the placenta

9. Placenta ________: membranous layer immediately surrounding the fetus Forms the amniotic sac Fetus floats in amniotic fluid inside the amniotic sac _________: layer surrounding amniotic sac; forms the allantoic sac Outside of allantoic sac is covered by the chorion _________: attaches to lining of uterus Chorion is linked to fetus by the umbilical cord _________: tube that connects the bladder to the allantoic sac

10. Placental Attachments ___________: spread over the whole surface of the placenta and uterine lining (pigs, horses) ____________: many small, separate attachment sites (ruminants) ____________: cotyledon on placental surface joins with caruncle in the uterine lining ____________: belt-shaped attachment that encircles the placenta (dogs,cats) __________: placenta and uterus attached at a single disk-shaped area (humans, primates, rabbits, rodents)

11. Placental Attachments

12. _________ period: time from fertilization of ovum to delivery of newborn Time varies among species Divided into three segments/trimesters First trimester: ____________ period Placenta develops Second trimester:__________ period Body tissues, organs, and systems develop Third trimester: fetal _________ period SpeciesGestation Cat2 mo Cat2 mo Dog2 mo Dog2 mo Cow9 mo Cow9 mo Elephant21 mo Elephant21 mo Ferret6 w Ferret6 w Goat, Sheep5 mo Goat, Sheep5 mo Hamster3 w Hamster3 w Horse11 mo Horse11 mo Human 9 mo Human 9 mo Pig3 mo, 3 w, 3 d Pig3 mo, 3 w, 3 d Rabbit1 mo Rabbit1 moGestationPeriods

13. Parturition __________ process Factors influencing parturition Size and weight of uterus and fetus Hormonal changes ↓Progesterone, ↑ fetal Cortisone causes mother’s estrogen level to rise and Prostaglandin F 2α to be released from the uterine wall The estrogen and prostaglandin increase the uterus’ sensitivity to oxytocin, which is now being released by the posterior pituitary Myometrium in uterus begins to contract due to the oxytocin, beginning labor Fetal changes at birth: _________ expand and begin to function Foramen ovale and ductus arteriosus ___________

14. Stages of Labor  First stage - uterine contractions Myometrium contracts and presses fetus down against cervix Sustained contractions cause cervix to gradually dilate  Second stage - delivery of newborn Results from combination of strong uterine and abdominal muscle contractions Rupture of amniotic and allantoic sacs of placenta may precede actual delivery of newborn  Third stage - delivery of the placenta Placenta separates from wall of uterus and is expelled by weaker uterine contractions http://www.clemson.edu/cafls/departments/animal_vet_science/behavior_database/equine.html

15. Involution of the Uterus Uterus gradually returns to nonpregnant size Endometrium sloughs into lumen of uterus at sites of placental attachment Myometrium continues mild contractions to move remaining uterine contents out through birth canal May take from a few weeks to a month or more for involution to be complete

16. Mammary Glands Specialized skin glands that produce _________ and _______ Present in both male and female animals Males do not secrete proper amount of hormones to make them work Number and appearance of mammary glands differs among species

17. Udder of Cow Four mammary glands (__________) Quarters are completely separate units from each other Each quarter has its own milk-secreting system and ducts leading down to separate teats

18. Mammary _________: saclike arrangement of cells that secrete milk into alveolar duct Mammary _________: saclike arrangement of cells that secrete milk into alveolar duct Arranged like clusters of grapes around alveolar ducts Arranged like clusters of grapes around alveolar ducts Smaller alveolar _______ join to form larger ducts Smaller alveolar _______ join to form larger ducts Largest ducts empty into _______ sinus Largest ducts empty into _______ sinus located just dorsal to teat Continuous with ______ sinus inside teat Continuous with ______ sinus inside teat Milk accumulates in sinuses Milk accumulates in sinuses Alveoli and Duct System

19. Milk Letdown Milk accumulates high up in mammary gland in alveoli and small ducts Physical stimulation of nipple or teat sends sensory impulses that cause release of oxytocin from post. pituitary ___________ causes contraction of ___________ cells around alveoli and small ducts Moves milk down into large ducts and sinuses

20. Mammary Gland Development Mammary glands develop in response to hormones produced at ____________ Prolactin and GH directly encourage mammary gland development Estrogen and progesterone produced by the ovaries during the estrous cycle encourage mammary alveoli and duct systems to develop. TSH and ACTH can also promote mammary development

21. Colostrum “First milk” Pre-milk secretion Imparts _________ __________- transfer of preformed __________ from dam to newborn Supplies important nutrients to newborn proteins, lipids, amino acids, and vitamins __________ effect helps clear meconium from newborn's intestinal tract

22. Lactation Physical stimulation of teat or nipple and regular removal of milk from gland stimulates pituitary to continue release of hormones that keep lactation going prolactin, oxytocin Lack of hormonal/physical stimulation combined with increased pressure in the mammary gland gradually causes lactation to cease