ANS3319Exam3_Fall2011_Key - ANS 3319C Reproductive ...

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Unformatted text preview: ANS 3319C Reproductive Physiology & Endocrinology in Domestic Animals Exam 3 (100 pts: November 18, 2011) Name: _______________________________ Please note that this exam was only worth 94 pts as question 4a from page 4 was removed from exam. Please place the most appropriate term in each blank (1 pt each). 1) Estrogen Steroid hormone that stimulates cervical secretions during estrus. 2) Uterus Reproductive structure that produces the luteolytic signal in farm animals. 3) eCG Hormone that stimulates the development of accessory CL in mare. 4) Acrosome Reaction that allows sperm cell to digest and penetrate zona pellucida. 5) Neutrophils Powerful phagocytic white blood cells found in uterus that digest sperm cells. 6) Ovary Thought to be the origin of the luteolytic signal in humans. 7) mesoderm Embryonic germ cell layer that develops into muscle and skeleton. 8) Inner cell mass Group of cells in blastocyst that eventually develop into embryo proper. 9) Capacitation Biochemical process that occurs to sperm and infers fertility on sperm. 10) Cortical Biochemical reaction that initiates the zona block and prevents polyspermy. 11) Meiosis I Resumption of this cellular event within oocyte that occurs because of LH surge. 12) Ectoderm Embryonic germ cell layer that develops into skin, hair, and central nervous system. 13) Interferon tau Maternal recognition of pregnancy signal in sheep & cattle, which is secreted by conceptus. 14) PGF2alpha Lipid derived hormone that has luteolytic actions in farm animals and humans. 15) Trophoblasts Cells of blastocyst that eventually develop into chorion of the placenta. 16) Turkey Tom What is your favorite food to eat on Thanksgiving day? 17) hCG Hormone produced by chorion and basis for pregnancy testing in humans. 18) Paramesonephric Early embryonic ducts that eventually develop into female reproductive tract. 19) TDF Sexual differentiation is controlled by a gene on the Y- chromosome called what? 20) Cervix Female reproductive structure that serves as both a barrier and reservoir for sperm. 21) Mesonephric Early embryonic ducts that eventually develop into male reproductive tract. 22) Oxytocin Protein hormone secreted by corpus luteum involved in luteolysis in ruminants. 23) Glucose Primary nutrient source for fetus, which crosses the placenta by facilitated diffusion. 24) Apoptosis Another name for programmed cell death, which is involved in luteal regression. 25) Endoderm Embryonic germ cell layer that develops into digestive and respiratory systems. 26) Crytochid Animal that has either one or two testis failing to descend into the scrotum is called what? Page 1 of 4 ANS 3319C Reproductive Physiology & Endocrinology in Domestic Animals Exam 3 (100 pts: November 18, 2011) Name: _______________________________ Short answer and fill- in- the- blank. 1) The figure below illustrates the follicle development patterns and hormone profiles that occur during the estrous cycle in the cow. Please answer the following questions as they relate to this diagram. Please spell out all words. Y X Z 0 a. What ovarian event is indicated by the letter “Z” (2 pts)? Ovulation b. Surge of what pituitary hormone is responsible for ovarian event “Z” (2 pts)? Luteinizing hormone c. Steroid hormone secreted by follicles labeled “D” (2 pts)? Estrogen d. Protein hormone secreted by follicles labled “D”, which slows follicle recruitment (2 pts)? Inhibin e. Please name the hormone depicted by the line labeled “X”, the ovarian structure that secretes it, and describe what significant ovarian event this hormone prevents from occurring throughout the luteal phase of the estrous cycle? Please explain your answer from an endocrine standpoint (6 pts). Progesterone is secreted by CL. It prevents ovulation because it inhibits GnRH and LH secretion by preventing the preovulatrory surge of LH so that ovulation does not occur. f. The hormone in question 1e) or synthetic equivalent can be administered to mares to enhance early embryonic survival and maintenance of pregnancy. Based on what you know about the function of this hormone, please provide two functions that this hormone could have on the uterus to help maintain pregnancy (4 pts). 1. Enhancing uterine secretions to provide a suitable environment for the pregnancy. 2. Negative effect on myometrial contractility so the fetus will not be expelled. Page 2 of 4 ANS 3319C Reproductive Physiology & Endocrinology in Domestic Animals Exam 3 (100 pts: November 18, 2011) Name: _______________________________ Short answer and fill- in- the- blank. 2) Please answer the following questions as they relate to placental function in mammals. a. In a single sentence, please describe the primary functions of the placenta relative to how it allows for fetal growth and development as well as survival (2 pts)? Apposition of fetal membranes to maternal endometrium to permit physiologic exchange of gasses & other nutrients between fetus & mother. Needed to say something about nutrient and gasses b. Please list the types of placenta observed in these mammals based on their chorionic villi pattern (12 pts). Additionally, indicate the gestation length in days for each animal. Dog: zonary (60- 70) 65 Cow: cotylendonary (273- 293) 283 Pig: diffuse (111- 115) 113 Cat: zonary (60- 70) 65 Horse: diffuse (320- 340) 330 Human: discoid (260- 280) 270 c. The placenta has four major physiological functions that are similar to different organ systems found in the postnatal adult. These functions allow the fetus to grow and develop in utero. Please list them (8 pts) 1. GI tract 2) Lungs 3) Kidney 4) Endocrine d. Of the four functions listed in the previous question (1c), circle the one that has physiologic & metabolic effects on the pregnant dam via hormone production and provide four short descriptions of these effects (6 pts). 1. Maintains pregnancy by (+) secretion of progesterone 2. Enhances mammary gland development 3. Assist in parturition 4. Stimulates ovarian function 5. Enhances fetal development e. You are a world renowned research scientist and are interested in studying what effect different drugs and environmental contaminants have on early embryonic development in mammals. If you had to choose either a ruminant or rodent, which species would probably serve as a better experimental model for your research? Please explain your answer by comparing and contrasting why one has an advantage over the other (6 pts)? I would choose the rodent because it has a hemochorial placental where the fetal chorion is in direct contact with the maternal blood supply and contaminants can easily cross the placental membranes. In contrasts, the ruminant which has a epitheliochorial placenta where there are six layers between the fetal and maternal circulations, which makes it more difficult for contaminants to cross from the maternal circulation to the fetal circulation. Page 3 of 4 ANS 3319C Reproductive Physiology & Endocrinology in Domestic Animals Exam 3 (100 pts: November 18, 2011) Name: _______________________________ Short answer and fill- in- the- blank. 3) Please list the three major placental membranes in mammals. In line a, start with membrane nearest the fetus and list the remainder as you move toward the uterus. Also, provide the primary function(s) of each membrane (8 pts)? a. Amnion: fluid filled protective sac surrounding the fetus b. Allantois: carries the blood vessels to and fuses with the chorion, collects waste fluid from fetus c. Chorion: fuses with chorion and attaches to the uterus and allows for nutrient (metabolic) transfer 4) There are several cereal grains fed to livestock that produce molds & mycotoxins when stored incorrectly. Some of these molds & mycotoxins have estrogen- like- activities when ingested at high concentrations. a. A farmer who raises pigs that are being fed the feed described above has noticed that some of her 5 month old gilts (they have all attained puberty) are exhibiting estrous cycles that are 50 days long. She has indicated that the gilts have not been mated with a boar yet either. Please provide the farmer a logical explanation for this abnormal observation. In your answer please provide the endocrine mechanism behind this (6 pts)? Estrogen produced by the conceptus is the maternal recognition of pregnancy signal in swine. Therefore, the gilts could be consuming tainted feed that has estrogen like activity, which can stimulate the system to make the gilt think she is pregnant resulting in irregular length estrous cycles depending on the duration of consumption of the contaminated feed. The estrogen cause that PGF to be secreted in an exocrine fashion, which does not allow for CL regression in non- pregnant pigs and expression of estrus. Only four people got this question correct. Therefore, it was removed from the exam. , b. If the same cereal grain from the previous question is fed to young sheep that are approximately 35 days pregnant (gestation length: 150 days), some lambs may actually abort their pregnancies. Please provide one mechanism by which the lambs are aborting their pregnancies (4 pts). Since the grains have some estrogenic activity, estrogens can stimulate uterine contractions, which causes the fetus to be expelled. 5) You are a young scientist who wants to develop an effective birth control method for women that does not involve steroids like those found in “The Pill”. Your goal is to immunize women so that fertilization of the oocyte does not occur after copulation. What would be a specific target associated with the oocyte that you would focus your research on to prevent fertilization from occurring? Please explain your answer (4 pts). You could target the “ZP3” protein, which would prevent the binding of the sperm head to the oocyte and prevent fertilization. This binding has to occur so that the acrosome reaction can occur and the enzymes can digest the zona. Page 4 of 4 ...
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