Anatomy and Physiology 1( BIOL 2401)

Case Study 3

An Unusual Case of Animal Reproduction

NATIONAL CENTER FOR CASE STUDY TEACHING IN SCIENCE

Joann B. Powell Department of Biological Sciences Clark Atlanta University, Atlanta, GA Elethia W. Tillman Department of Biology Spelman College, Atlanta, GA

Student Name

Student ID number

2020SP Anatomy & Physiology

Biol 2402-73015

Andrea Smith was taking notes for her biology exam. Her professor has told her that the exam would cover, in part, the diferences between sexual and asexual reproduction. As she reviewed her notes and prepared for today’s class, she was thinking about her own reproductive dilemma.

If only asexual reproduction were the case for humans, maybe she wouldn’t be in this mess. Or at least there wouldn’t be questions about who was the father of her twins. “Dwelling on it isn’t going to help me prepare for class, and right now I have got to f nish this chapter on animal reproduction,” she thought.

She tried to concentrate and forget about her current dilemma as she feverishly typed on her notepad: Asexual or sexual reproduction: 3 types of asexual reproduction:

1. fission (2) budding (3) fragmentation

2. NOTE: Be able to explain the differences between sexual and asexual reproduction!

She suddenly let out a long sigh. “It’ll be fne,” she thought. “I just hope that none of my family or friends watches the show. What was I thinking when I agreed to this? But that’s what Xavier wanted, and I will do whatever it takes to prove he is the father.

Besides I am going to need the money if I have to take care of these babies on my own!” The next day in class she was feeling even more nervous and was becoming increasingly angry as she thought about her current situation. Her thoughts were interrupted by the sound of her professor’s voice: “OK, class,” her teacher was saying, “that wraps up asexual reproduction.

Let’s move on to reproductive cycles and patterns. Most animals exhibit cycles in their reproductive activity. Reproductive cycles are often controlled by hormonal and environmental cues. Animals may reproduce either exclusively asexually or sexually while other animals alternate between the two methods. For example, some animals can lay eggs of two types, depending on the environment and/or season.

One egg type matures only if it is fertilized while the other type does not require fertilization for development, a process called parthenogenesis. Some animals, and in rare cases humans, have both male and female reproductive systems. Some hermaphrodites can fertilize themselves, but most must mate with a member of the same species. Please look over these handouts and answer the questions that follow.”

As the other students read through the assignment, Andrea was thinking: “I’m dealing with a case of sexual reproduction that no doubt started with the fertilization of my egg with, hopefully, Xavier’s sperm.

That reminds me, I need to make sure I go over internal and external fertilization again in my notes. I’m not sure I completely understand it.”

All this started the night Xavier had come came over to talk to Andrea about their break-up. He had smelled and looked so good that evening. The events of that night had left Andrea wondering if there was really some truth to that stuf about pheromones, which Andrea has learned in her class were chemical signals released by one organism that infuence the behavior of another individual of the same species.

Even though Andrea had met someone else and had been seeing Neo for a while, she hadn’t been able to resist Xavier. Neither she nor Xavier had behaved like themselves that night. It was unlike them not to use some barrier method of contraception like condoms or a diaprhram.

As the class wrapped up, Andrea’s mind was still on her upcoming appearance on a daytime talk show. In some ways she was dreading it; but she was determined to prove what she believed she had known all along: That Xavier was the father of her twins.

Part I – Conception

1. What is the difference between asexual and sexual reproduction?

In asexual is when an organism more of itself and does not exchange genetic information to other organism by way of sex. In the other hand sexual reproduction does share genetic information to other organism by way of sex. The sexual reproduction will have genomes of the two parents by combining to create offspring. Meiosis is only applicable to sexual reproduction.

2.List and define some types of asexual reproduction. Give one example of each.

Some of the types off asexual reproduction are fission, fragmentation, budding, vegetative reproduction, and parthenogenesis. In fission the process is of two parents’ cell are splitting into two identical daughter cells are of the same size. An example of fission is bacteria, or fungi. Fragmentation is asexual reproduction of a parent breaks into to fragments, or pieces, in which each fragment is developed into a new organism. Fragmentation some example are starfish and some worms. Budding is occurring when a parent organism produces small buds, and it breaks away. An example of budding is jellyfish. Vegetative reproduction is that of new plants grow form the specialized parts, such as tuber or bulbs that breaks off the adult part and no seeds are needed. An example of vegetative reproduction is a plant. Parthenogenesis it is offspring are developing from an unfertilized egg. An example of parthenogenesis is bee or birds.

3.What is the difference between parthenogenesis and hermaphroditism?

The difference between in parthenogenesis and hermaphroditism is that of parthenogenesis reproducing by which insects are being developed from unfertilized egg with no sperm. In parthenogenesis is considered asexual an example of it is lizards. In hermaphroditism is a reproduction by which an individual organism is bearing by way of both male and female gonads. A sexual reproduction system. Is a hermaphroditism. An example of hermaphroditism is a earth worms.

4.What is the difference between internal and external fertilization?

In internal fertilization occurs inside of the body of a female. For example, in Internal fertilization is mammals, birds and reptile. In the external fertilization is when the fertilization is done outside of the body like the aquatic environment. In external fertilization can be toads and frogs.

5.What is the function of pheromones?

“ The function of pheromone is that of a chemical capable of acting in the hormones outside of the body of the secreting individual. The pheromones have an impact in the behavior of the receiving individual for example sexually and can affect behavior or physiology. The pheromones can be detected by the olfactory and it is a way of attracting an individual of the opposite sex. It can also help alter danger around the surroundings.

Part II – The Pregnancy

“I can’t believe it has come to this! Airing our dirty laundry on national television. I never thought Xavier would let things get so out of hand.” It was late and Andrea was so upset she couldn’t sleep. She tried studying for the upcoming exam, but she couldn’t concentrate. She decided to get an early start on packing. She was so angry with Xavier. How could he have left her pregnant and alone, she thought, as she neatly added her new dress to the bag? How could he think that their babies might belong to someone else? She grabbed her journal, about to add it to the bag, but instead sat in her cozy corner chair and began to read:

January 12, 2007

I’m pregnant with twins! Sometimes it’s still hard to believe because it was so unexpected. I feel like I am about to pop! I know that Xavier is the father of my babies and I can’t wait for us to be a family. But he has doubts about it all because he knows that I met someone else during the brief time that we split up. And he wants to be sure that he is the father before we can move on. But what if it is Neo, the new guy I met? Tere’s a slight chance but I doubt it. I know the exact time of conception. It was the night Xavier came over to talk about our relationship. It was a little over a week after that night that the pregnancy test detected the increase in HCG. I guess I just missed him so much. I do regret that Xavier hasn’t been around much during the pregnancy. He has missed the development of our babies. In the past months, I have heard the babies’ heartbeats and felt them moving around. I wish he would come back because it’s obvious that I am pregnant now. Hopefully we can talk through our diferences and get back together before the pregnancy gets difcult—the frequent urination and back pain my OB/GYN keeps warning me about. I know there is no way he will ever let me go through labor alone. I only pray the contractions are not more than I can bear. Xavier seems committed to the idea of a paternity test. Hopefully it won’t come to that, but if it does, we’re going to a daytime show to f gure all this out.” “Wow! Tat seems like a lifetime ago,” she thought. “Now we have these beautiful twins and we don’t seem any closer to becoming the real family I dreamed about. Well this will all be over in a couple of days. I am 110% conf dent that the twins belong to Xavier, not Neo. I can’t wait to see the look on Xavier’s face and hear him apologize once he sees the results of the paternity test!”

1. What does Andrea mean by time of conception?

The time of conception is the time when sperm travels through the vagina, into the uterus, and the fertilize egg goes through the fallopian tubes. Ovulation occurs during the part of a women’s menstrual cycle. In ovulation would fall around 14 to 28-days cycle, occurring around the midpoint of a woman’s menstrual cycle. During ovulation, one of the ovaries release an egg, which in return travels down the fallopian tubes. If there is a sperm present in the fallopian tube the sperm could fertilize the egg. When the sperm and the egg meet and fertilize the woman gets pregnant. The sperm can remain alive within a 5 day period.

2. How is HCG used to determine pregnancy?

A women’s placenta produces a hormone that is HCG (Human Chorionic Gonadotropin) which is called the pregnancy hormone. If you are pregnant, a test is given which is the HCG that detects this hormone in your urine 10 days after you first missed your period. This is the time a fertilized egg attaches to the uterus. This test is a quantitative test that detects the hCG hormone in your urine. The presence of hCG is a positive result for being pregnant.

3. List some changes that occur with the fetus/mother during the 1st, 2nd, and 3rd trimesters.

In your first trimester of your body you will go thru a series of changes in your body. They will range from hormonal in which the pregnancy will affect almost every organ in the body. Some of the signs of the first trimester are extreme fatigue, tender or swollen breast, nausea (morning sickness), cravings, mood swings, constipation, and frequent urination. In the first trimester the fetus goes thru different phases of growth. The first 4 weeks you baby is developing the nervous system, heart, arms and legs. The last 8 weeks of the first trimester the fetus has developed all major organs, heart begins to beat, arms and legs begin to grow longer. In this trimester we can also find that the fetus fingers and toes have begun to form, sex organs and face begins to fully develop. Th first trimester is around the 12weeks. The second trimester is much easier because you do not have the morning sickness and do not feel as tired. The mother goes thru a series of changes in her body which are back, abdomen, groin, or thigh aches and pains. She can see that on her abdomen she in getting stretch marks and darkening of her skin around her nipples. The fetus in this trimester around 16 weeks is the musculoskeletal system is continuing to form, skin begins for form and nearly translucent. In 20weeks of the second trimester the fetus is more active and starts to have fine hair. The fetus eyebrows, eyelashes, fingernails, and toenails have formed. On week 24 the fetus begins to form bone marrow to make blood cells. The fetus footprints and fingerprints have formed. You can see if you are having a boy or girl because the testicles and uterus are seen in this trimester. The third trimester has an emotional and physical change in a woman when she is pregnant. She might have swollen of ankles, fingers, and face. She can experience the discomfort of hemorrhoids. Her breast can be tender, protrude belly button, and her belly is moving at a downward direction. The third trimester the fetus at week 32 the bones are soft are fully formed. The fetus kicking and moving is increase. The eyes can open, lungs are fully developed, stores minerals and iron at the third trimester. Week 36 the protective waxy coating thickens, and body fat is increased. On week 37-40 is considered full term and it is considered capable of functioning on its own. As you are nearing your due date the fetus is beginning to position for birth.

4. What hormones are responsible for inducing and regulating labor? There are four major hormones that are involve with labor and giving birth.

The hormone that is used to induce and regulate labor is estrogen, progesterone, oxytocin, beta-endorphins, prolactin, and epinephrine/adrenalin and norepinephrine/adrenaline.

In inducing and regulating labor oxytocin is the love hormone, which is which is released during sex, birth, and breastfeeding. Oxytocin reduces stress, calms you down and helps with the pain that is experience during labor. Beta-endorphins reduce pain and suppress in the immune, which is important and does not act against the baby. In the epinephrine and norepinephrine in the late-labor stage is the woman perceive danger or stress, they may paradoxically stimulation of the giving birth more quickly. A rise of epinephrine when a woman increases in levels of prostaglandin and cortisol to help with contraction. This epinephrine rise will cause might make a woman sudden rush of energy and will cause a higher contraction and help you push.

5. What trimester is Andrea in during this journal entry?

She can listen to the babies heart beat. Also, came to the conclusion of her being in the First trimester because she still does not know the genders of the twins.

Part III – The Results

Andrea replayed the words over and over again in her mind: “Xavier, you ARE the father!” She was ecstatic. Finally, she could breathe, knowing that Xavier was the father of her babies.

Then she heard what the host had to say next... “Neo...YOU ARE the father!” Andrea looked around in disbelief. She heard herself saying, “What do you mean? You just said Xavier was the father! If Xavier is the father, how can he be the father?” she asked as she pointed toward Neo.

“Well, this is a frst, even for our show. But it appears that your twins were fathered by both of these men.”

“I can’t believe it. The frst time I do something like this and I end up with twins and two fathers! Not only did I expose myself to potentially deadly STDs, but now I have two children, whom I have no doubt that I will be raising alone, and I have put my school career in jeopardy,” Andrea thought.

She still couldn’t believe this was really happening to her. How was it possible that her TWINS have dif erent fathers? What were the events that must have happened within her body that could lead to these circumstances? She grabbed her journal from her bag and fipped back to the entry describing her feelings the day she found out she was having twins:

August 23, 2006

I just came back from another Dr’s appointment. Dr. Blossom informed me that I am having two babies— twins—fraternal. I don’t know if they are boys or girls yet. One could be a boy and the other a girl. I still can’t believe this has happened. Xavier has to be the father. He has to be! I will have to just play the hand I have dealt myself. How stupid was I? I was going to practice abstinence after Xavier and I broke up...and I certainly wasn’t planning on meeting and getting involved with Neo! I can’t believe that Neo and I didn’t use a condom either. And it’s no excuse that we had been drinking. I just got caught up in the moment with Xavier—going down memory lane and things got all sentimental. I could have at least thought to use the rhythm method and kept track of when ovulation may occur. Tis has to be the most irresponsible thing I have ever done! Why did I stop taking my birth control pills anyway? And I have no idea where I put that diaphragm. Undoubtedly, some people will judge me as the type of woman who should have a tubal ligation that would permanently prevent any pregnancy. Everything hit her at that very second. She closed her journal and just sat there for a moment. Andrea was reminded that she had stopped taking the pill the month before she became pregnant. She remembered that physicians recommend that a woman wait at least one cycle after she stops taking the pill before becoming pregnant because there is a chance that multiple ovulations may occur. Did it have something to with oogenesis? Andrea was so confused she just couldn’t keep things straight in her mind. She thought about it for a minute to let it all sink in. Andrea sat back and thought about the lecture on animal reproduction the week before. She pulled out her lecture notes on the menstrual cycle, the basic foundation of everything that she was going through.

1. Describe the two types of cycles that occur in female mammals (menstrual vs. estrous)

In estrous the period of time when a female mammals are looking for a sexual mate.

The monthly series of events associated with the maturation of an egg. The ovarian cycle goes thru different phases the follicular phase which is were the follicle growth takes place is done within 1-14 days. The follicular phase it starts at what is called the primordial follicle, directed by the oocyte, it becomes a primary follicle. The primary follicle becomes a secondary follicle that has granulosa cells that produce estrogen. The zona pellucida forms around the oocyte and the antrum(space) is formed.

The secondary follicle becomes a vesicular follicle. The antrum expands and isolates the oocyte and the corona radiata. The full-size follicle bulges from the external surface on the ovary. In this stage the primary oocyte completes meiosis 1, and thee stage for ovulation begins. In ovulation occurs when the ovary wall ruptures and expels the secondary oocytes.

Mittelschmerz is a symptom, were some women experience pain and discomfort in ovulation. The last phase is luteal which is after ovulation, with the rupture of follicle collapses and granulosa cells enlarge and form the corpus luteum.

In the uterine menstrual cycle, there are also a couple of phases that must happen so that a woman can menstruate. The series of cyclic changes that the uterine endometrium goes through each month is a response to the ovarian hormones that are present in the blood.

Menstrual phase takes place in days 1-5 in the uterus shedding all of the deepest part of the endometrium. In the proliferative phase endometrium rebuilds itself. The last phase is the secretory phase endometrium preparing for implantation of the embryo.

2.Compare and contrast the sterilization techniques (vasectomy and tubal ligation) and the temporary and reversible methods discussed the case.

Tubal ligation is a permanent solution to birth control for women and is done by a procedure called laparoscopic. The procedures involve cutting and tying the fallopian tubes to prevent the eggs from moving from the ovaries to the uterus and block the sperm from reaching the sperm and getting pregnant. The pros of tubal ligation no longer birth control in take and most important no worries of getting pregnant. The cons of tubal ligation perforation of the intestine, infection, complication is anesthesia. You have

.25% to .5% for surgery to fail.

The surgery does not protect against sexually transmitted diseases. Vasectomy is considered a permanent method of birth control for men it will prevent the sperm when ejaculation. A vasectomy in a man will not affect the ejaculation is going to feel the same the only thing the sperm will not be in the seminal fluid.

The pros of the vasectomy the procedure will take less than 30 minutes in the doctor’s office. The procedure involves in severing the mans vas deferens, then the doctor tries to less than in manner to prevent the sperm from entering into the seminal stream therefore preventing the female from being pregnant. The procedure does not affect the testosterone levels. Having a vasectomy does not put a man on high risk of prostate cancer.

The cons of vasectomy are if you decide to reverse the vasectomy is an extremely high risk and not very successful.

3. What are the functions of GnRH, FSH, LH, estrogen, and progesterone?

The hypothalamus secretes the gonadotropin-releasing hormone (GnRH). This hormone is being stimulated by the anterior pituitary to secrete the follicle stimulating hormone (FSH) and luteinizing hormone (LH) into the blood. Hormones on females have a different phase then men.

The hormones during interaction of ovarian cycle and follicular phase starts of with days1-13 the GnRH stimulates the release of FSH and LH. FSH and LH stimulate the follicle growth and maturation and the low-level of estrogen release. When the rise of estrogen is inhibited by the release of FSH and LH. The pituitary is synthesized and accumulates these gonadotropins. During the ovarian cycle and follicular phase, the estrogen level increases, and the high estrogen level has a positive feedback effect on the pituitary, in return it causes a sudden surge in LH.

During the ovarian cycle and ovulation, the LH spikes stimulating the primary oocyte to complete meiosis 1, and the secondary oocyte continues on the metaphase 2. On day 14 the LH trigger ovulation. On day 14-26 the LH transforms the ruptured follicle into a corpus luteum. On these days, the LH produces inhibin, progesterone, and estrogen the FSH and release LH declining LH ends luteal activity.

Days 26-28 decline for ovarian hormones ends the blockade of FSH and LH the cycle will restart a new cycle. In females the effect. On of the effect is uterine tubes, uterus and vagina grow larger and become functional. Uterine tubes and uterus exhibit enhance motility and vaginal mucosa thickness and external genital are mature. Estrogen had an inducing secondary sex characteristic which are growth of breasts, widening and lightening of the pelvis and growth of axillary and pubic hair.

In males the sex hormone is controlled by the testosterone. This testosterone develops and functions of the reproductive organsm,sexual behavior and drives, and the growth and development of many other organs and tissues. In males the released of sex hormones controlled by hypothalamus. The hypothalamus is ultimately in charge of male and female reproduction it acts by way of the pituitary gland by releasing the hormones.

In the testicular regulation involves three sets of hormones are in GnRH which indirectly stimulates the tests through the gonadotropins which directly stimulate the testes and ovaries. The follicle stimulating hormones (FSH) and the luteinizing hormone from the anterior pituitary.

The hormonal regulation of the testicular function is when the ABP binds the testosterone causes spermatogenesis. FSH and testorerone both are requiring for the spermatogenesis to occur. The testosterone is the basis of libido in the male and female which is the sex (sex drive).

4.How can the paternity results be explained? Your answer should consider the amount of time before and after ovulation a woman is at risk for pregnancy and how long sperm can survive in the reproductive tract. Your discussion should include the following terms: ova, oogenesis, and fertilization, etc.

When talking about reproduction we must take in consideration the different stages or cycles that a woman goes thru to get to a pregnancy. The woman starts in the mother womb by have what is called oogonia (ovarian stem cells) which is multiply by mitosis and store the nutrients. At birth, the woman has up to 5,000 cells. The first phase of the process is what is called primordial follicles which appear as oogonia then is transferred into primary oocytes. The primary oocytes begin meiosis but stall in the prophase oocyte produces two haploid cells.

The first phase which is before puberty. The primary oocytes are activated at puberty is one activated primary oocyte produces two haploid cells. The first of the cells are polar body and the other is called the secondary oocyte. The secondary oocyte is what stops developing and gets stuck to sperm and in metaphase 2 ovulation starts. By the penetration of sperm, the second oocyte completes meiosis 2 yields. There are 4 functional cells of what we call sperm for 1 functional cells of a woman for the ovum to get to gather with sperm and the result will be pregnancy. A large ovum which is a functional gamete is the one that get together with the sperm. The time of the survival of the sperm is up to 5 days.

In this case study we see that Andrea is hit a big dilemma having to deal with having twins from two different fathers. It is possible to have twins from two different father this is called heteropaternal superfecundation. This phenomenon is when two of a women’s eggs are fertilized by the sperm of two different men. The ovulation period is on the 14 day of the menstrual cycle and after 14 days you have a period of 6 to 8 days to become pregnant. So, Andrea did have a high possibility being pregnant. She released multiple eggs within a week of one another. Which in this narrow time frame, two eggs appear to have been fertilized by the sperm from two different men. The result is going to be that she going to have fraternal twins with two different fathers.