Ovaries

Today, I tackle a body part upon which I consider myself to be somewhat of an expert. Had my left ovary behaved years ago, I would not be typing this today–and I would still have both ovaries. Speaking with other women, it becomes obvious very quickly that we tend to know very little about our ovaries.  Hopefully, I will shed some light on this for you today!

Where are the ovaries?  It’s safe to say we know they’re in our pelvis, but where exactly?  A good estimate is to make a triangle with with your index fingers and thumbs and place that over your pelvis with the index fingers pointing downward.  In the upper corners is about where your ovaries are.  (They tend to be a bit lower and more centralized than most assume they are.)  The ovaries are held in place by a network of ligaments which also attach to the uterus and Fallopian tubes.  The ovaries are not connected directly to the Fallopian tubes.  Many diagrams shows the fimbriae (the leafy looking parts on the far left and right below) of the Fallopian tubes as been directly adjacent to the ovaries, which leads many to believe that the ovaries are directly attached to them.  They are not.  (Read more about the relationship between the ovaries and the Fallopian tubes in the section about Fallopian tubes.)


The ovaries are, ironically, shaped like eggs but are smaller than the chicken eggs that one typically purchases at the grocery.  The ovaries are about the size of a walnut, are slightly pearl colored, and have bumpy, soft surfaces.  The ovaries are responsible for producing a variety of sex hormones.  At birth, the ovaries of a healthy baby girl contain between one and two million eggs.  By the time puberty begins, most of these have wasted away leaving about 300,000 eggs–plenty for the reproductive lifespan.  Thus, a woman has a finite number of eggs, but men have a different mechanism that continually makes sperm.  This is why women have “childbearing” years, but men can father children throughout their adult lives.

The eggs have a complicated lifespan before they are even released for potential fertilization.  The term “egg” is generic and refers to a single cell’s journey through maturation.  Before maturation, the egg is referred to as an oocyte.  Once it finishes maturing (see diagram below), it becomes an ovum and three polar bodies.  The polar bodies are actually inside of the ovum and serve to “fuel” the egg once it is fertilized continuing cell division and replication before it implants in the uterine lining (where it forms a network of blood vessels that forms the placenta and umbilical cord).

Each month, the ovaries usually release one mature egg (not one from each).  The ovaries are covered in cells called follicles and within each follicle is a single egg.  Once an egg is matured, the process of ovulation can begin.  During this time, the follicle that houses the mature egg expands and eventually ruptures forcing the egg outward.  This rupturing is completely normal–it would be abnormal for ovarian follicles to never rupture, and in fact some women can actually feel a quick pain when the rupture occurs.  The diagram below is an illustration of the ovulation process, beginning in the upper-left hand corner and going clockwise.


Following a woman’s “childbearing” years, the ovaries continue to play an important role.  For years, many doctors prescribed a surgery called a hysterectomy to remove the ovaries (as well as the uterus and Fallopian tubes) once a woman was finished having children.  This was performed to prevent cancer from developing.  However, we now know that ovarian cancer can actually develop anyway after the ovaries have been removed.  This is because the ovaries share tissue with the internal cavity that remains following a hysterectomy.  Leaving the ovaries intact provides a number of hormonal benefits throughout menopause that are difficult to replace.  Thus, the benefits of leaving the ovaries intact often outweigh the drawbacks.  (This is something that should be discussed with a physician, because each individual has a different medical history that will affect any such decision.)

There is a lot more that could be said about ovaries, but let’s save that for another day.  Hopefully this gives you a better understanding of how the ovaries work!

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The Big C: Cancer–The Disease in a Nutshell

Cancer is arguably the most feared disease in the Western world.  In America, cancer is the leading cause of death of people between 35-65 years of age.  Nearly 1 in 7 deaths worldwide in 2007 was due to cancer.  Cancer rates are exploding throughout the world as developing nations industrialize and eat diets that are less nutritious (think of pollution and McDonald’s).  Because of physiological and social reasons, gynecological cancers are some of the most lethal types of cancer in women.  To better understand gynecological cancers, let’s take a step back and get to grips with the basics of cancer.

Cancer is a disease affecting humans, and other animals, that is a result of abnormal cells growing out of control.  Cancer can happen in virtually any part of the body and there are more than 100 distinct types.  The cells in our bodies are continually regenerating.  There is a saying that our bodies completely regenerate every seven years.  (In fact, each type of cell–each part of the body– regenerates at a different pace.)  When our bodies dictate the script (DNA being the script) that causes cell reproduction, occasionally there is a typo.  Many different things (such as smoking) can cause a “typo.”  When this happens, the body has difficulty righting the mistake and it can grow out of control resulting in cancer as seen in this illustration:


The top half of the illustration is a process called apoptosis, by which a damaged cell is removed through programmed cell death.  (I jokingly think of apoptosis as telling a “bad cell” to “pop off.”)  A lack of apoptosis is when the damaged cells are not programmed out.  This is where cancer begins.

If this growth of abnormal cells is caught in an early stage, it usually can be treated easily by removing the growth.*  Stages are a means by which the cancerous growths can be classified by how far along it has progressed.  There are four main stages, and with specific types of cancers there are further subdivisions such as “Stage II-C.”  Usually by the time a cancerous growth has reached the fourth, most advanced stage it has undergone a process called metastasis.

Metastasis is when the cancer spreads from its primary site to other sites.  So, if you hear an official cancer diagnosis, it may sound something like, “metastatic breast cancer” or “metastatic cancer primary to the liver.”  This indicates where the cancer began and that it is present in other locations.  Metastasis usually occurs through the body’s lymphatic system.  That’s why one often hears about lymph nodes in relation to cancer.

There are innumerable ways in which cancer is diagnosed.  Once it is found and diagnosed, there is a great divergence between how cancer behaves and how it is best treated depending on the type of cancer, medical history, and other factors.  If you ever find yourself receiving a cancer diagnosis, you will need to create a very specific plan with your physicians–no two diagnoses are ever exactly identical.  Hopefully this brief overview of the Big C helps build your understanding of the disease if you ever find yourself in close contact with cancer.

*(In my case, I had a very slow-growing cancer.  So, even though it was not caught at all “early,” it was still in an early stage.)

The Uterus

Pound for pound, the uterus is the strongest muscle in the human body. The uterus weighs about 40 ounces (2.5 pounds; 1.1 kg) and is about the size of a pear when not pregnant. Yet, in the process of giving birth, the uterus can exert over 100 pounds of force (440 newtons). The uterus is responsible for protecting and nursing a growing fetus during a pregnancy, and also for pushing that fetus out when it’s time to give birth. Let’s further explore this great muscular feat of nature–the human uterus.

The word uterus comes from Latin meaning “womb” or “stomach.”  It is an organ particular to mammals.  The human uterus consists of two parts:  the main body, generally just called the uterus, and the narrow “neck” called the cervix (Latin for “neck”).  In humans, the uterus is labeled as simplex because it is generally a single (simple) compartment, but sometimes the uterus does not end up like this.  When a female fetus is developing in the womb, it starts out initially as an organ shaped like a V–as though the cervix has two horn-shaped compartments.  As the fetus develops, the horns will generally fused into one, “simplex” uterus.  About 6.7% of the time, though, this does not happen resulting in a malformed uterus.

The most common type of malformation is the bicornuate (or “two-horned”) uterus.   Other malformations include unicornuate (“one-horned”) uterus, double uterus (two whole, functioning uteruses), and absent uterus (where the uterus fails to develop at all).  Each of these malformations has its own set of issues, and a medical professional can help counsel a person with a malformed uterus.

The uterus consists of three main “layers,” much like the different layers of skin.  The innermost layer on the inside of the uterus is called the endometrium.  It is a temporary layer that builds up and jettisons away over the course of a menstrual cycle.  The middle layer is called the myometrium.  This is the main, muscular layer of the uterus and consists of smooth muscle mass.  The outermost layer is referred to as the perimetrium.  It is a thin membrane that secretes serous fluid.

Uterus IllustrationIn the reproductive cycle, the uterus receives the egg after it has been fertilized while traveling down the Fallopian tube (labeled here as the uterine tube).  Once the fertilized egg is in the uterus, it will usually implant in the endometrial lining of the uterus (that is normally shed when a woman has her period).  From this implantation, the uterus and the embryo form a network of blood vessels that exist only during the pregnancy.  This is called the placenta and is what the umbilical cord is attached to.

The uterus, besides being key to the reproductive cycle, is also important in the sexual response cycle.  It directs blood flow toward the pelvis and outer genitalia during sex. This directed flow of blood happens during arousal and allows for sex to be pleasurable to the woman.  The uterus is also involved in a somewhat rare type of orgasm called, of course, the uterine orgasm.

The uterus is, arguably, the most central organ to not only reproduction but also sexual response.  Take good care of your uterus and go to the gynecologist for your regular check-up!  Have questions or comments?  Let’s hear ’em.

Linea Nigra and the “Mask of Pregnancy”: Skin Discoloration during Pregnancy

During pregnancy, a woman’s skin can undergo any number of changes.  This article will exam two of the most common of these dermatological changes:  “linea nigra” and the “mask of pregnancy.”

Linea nigra, which is Greek for “black line,” is a dark line that develops on a pregnant woman’s abdomen and can stretch from the pubic mound up to the navel or beyond.  (The length of the linea nigra can have great variation.)  Approximately three-quarters of all pregnancies exhibit linea nigra.  Scientists have not determined what exactly causes linea nigra, and its causes my vary from person to person.  The linea nigra can be more than just a colored line beneath the skin–it can include a new growth of dark hairs along the same axis.  This is all quite normal and no reason to worry

Linea nigra is more common among women with darker skin, hair, and eye pigmentation.  These lines usually appear approximately half-way through a pregnancy and can last well beyond the time of birth.  In some women, the line may persist throughout one’s life.  In others, the lines may disappear but recur due to increased sun exposure.  In most women, though, the linea nigra will eventually completely fade.  If you develop a linea nigra and you really don’t like it, the absolute worst thing you can do is to try to tan your skin to match.  Tanning will only make the line darker and darker and less likely to go away.  In general, it is good to avoid too much UV radiation (sunlight, tanning bed, etc.).  It is especially good to avoid UV radiation during pregnancy so as to prevent problems.  If you are worried about your linea nigra (the color, size, direction, etc.), make sure to consult a physician.  Overall, though, a wide range of different linea nigra is totally normal.

The second skin change I mentioned earlier is usually referred to as the “mask of pregnancy,” though its technical name is melasma.  Melasma is a discoloration of the face in a mask like pattern (think of masquerade masks).  The discoloration is a darkening of the skin and usually appears to be brown (light or dark).  The change in color primarily affects the nose, upper cheeks, and forehead.  In some cases, the melasma can affect other parts of the face.  Melasma can actually occur in both men and women, but it is most common in women who are pregnant.  Melasma also occurs frequently in women taking oral contraceptives (“the pill”).

Melasma, like linea nigra, usually fades with time and intensifies with exposure to sun (as well as tanning beds).  Melasma is totally normal but is more common among women who have naturally dark skin and who are often exposed to high amounts of sun.  There are several treatments to speed the fading of melasma, though they should not be used until after the pregnancy has finished because the chemicals involved may be harmful to the fetus.

Also note that moles, freckles, and areola (the area around the nipples) can also darken during pregnancy.  Like the above-mentioned skin changes, they are perfectly normal, can last for various amounts of time, and usually fade away after pregnancy.  The body goes through so many changes during pregnancy but these changes are among some of the most visible.  If you are ever worried about any of these changes, seek the advice of a medical professional.  Any questions or comments?  Please feel free to leave them here.

Teen Pregnancy and the Rhythm Method

I read in the news today about a report released a few days ago by the Centers for Disease Control (CDC).  The headline that emerged in numerous articles as a result of this report was that the use of the rhythm method to prevent pregnancy by teenagers rose from 11% in 2002 to 17% in 2010.  This is quite a jump.  The report was made to investigate why the teen pregnancy rate has risen markedly in recent years.  In fact, the United States has the highest teen pregnancy rate of any developed country in the world and one of the highest teen abortion rates.  So, I have decided it is time to tackle the issue of the rhythm method.

So, what is the rhythm method?  If there is such a great leap of teenagers responding that they have used it, it is pretty important for young women (you, the reader!) to understand what it is.  In general terms, the rhythm method is a means of birth control by which the female avoids sexual contact during the supposed window of fertility based on a calendric monitoring of her menstrual cycles.  In other words, if a young woman has a consistent 28 day menstrual cycle, she can estimate the days she will be fertile by following the “rhythm” of her menstrual cycle.  Here is an example of what a menstrual calendar would look like (with menstruating days in red and fertile days in green):

With perfect use, meaning that a young woman meticulously keeps track of her period without fail and strictly avoid sex on possibly fertile days, pregnancy still happens 9% of the time.  If you wanted to avoid pregnancy, would you really want to take a 1 in 10 chance?  But, keep in mind that virtually all forms of birth control are not used perfectly.  So, with typical use (a slip up here and there), the rhythm method results in pregnancy 25% of the time.  That is 1 in 4!  So, needless to say that the rhythm method is not a terribly effective means of preventing pregnancy.  Other factors make the rhythm method less reliable, especially for young women.  In particular, a woman’s period does not become regular (and therefore predictable) for quite some time after the first period, called menarche.  Hormones are in flux during adolescence and early adulthood, so the monthly time of fertility is particularly unpredictable for young women.  Other times in a woman’s life when the rhythm method is especially ineffective include just after giving birth (as hormones are again in flux), after discontinuing the use of a oral contraceptive (“the pill,” which manipulates hormones), and around the time of menopause when, yet again, hormones are in flux.  Hormones can be affected by a variety of factors including stress and emotions.  So, the rhythm method can never be 100% effective.

The rhythm method has generally been rejected as a useful means of birth control [page 375] (except, notably, by the Catholic Church) in the past few decades, so it is eyebrow raising that teenagers are suddenly reporting a significantly increased use of it.  The rhythm method was first proposed in the early twentieth century.  Before this time, the function of ovulation as the key to fertility was not yet understood.  When science could finally understand these processes, it was determined that in the normal menstrual cycle a woman ovulates once occurring about 14 days before the beginning of the next period.  When this was discovered, gynecologists promoted it to patients as a means to help promote pregnancy.  Some years later, in 1930, a Catholic physician in the Netherlands began to promote this as a means to help avoid pregnancy.  Catholic organizations in Europe and America also began to advocate this means of birth control throughout the 1930s.  By the 1960s, the popularity of the rhythm method as a means of birth control had begun to wane, especially with the introduction of the birth control pill in 1960.

Avoiding pregnancy is generally the point of using the rhythm method, but it extremely important to point out that the rhythm method in no way stops the spread of sexually transmitted diseases (and neither do birth control pills).  Condoms are the safest and most effective way to avoid spreading or getting a disease during sex.  Abstaining from sex altogether is the only 100% effective method of avoiding both disease and pregnancy.  So, if you are a young woman considering using the rhythm method, please keep all of this in mind.  If you have any comments or questions, I’d be glad to hear from you!

Müllerian Ducts and Sex Differentiation

Something that has always stuck with me since Intro to Biology years ago was something my professor said: females are the prototypical human sex. In other words, we all start out as females in a sense. It is not until around the 8 week benchmark in fetal development that a fetus starts to develop distinct sex characteristics. Generally speaking, from the moment of fertilization the embryo has an innate genetic sex (XX in a female; XY in a male). However, if you were to see a fetus before the 8 week mark, you would see that the genitalia is undifferentiated between XX and XY. That means that a female fetus and a male fetus look the same between the legs, so to speak.

So, why is that?  Why do female and male genitalia not differentiate from the moment of fertilization?  And what causes the differentiation when it happens?  And what did that professor mean by saying that females are the prototypical humans?  Well, it all has to do with the Müllerian ducts and hormonal reactions during pregnancy.

The Müllerian ducts are a set canals in the urogenital region of an embryo (that is, where the urinary and genital structures develop).  Depending on which way sex differentiation goes, the Müllerian ducts develop into the Fallopian tubes, uterus, and upper part of the vagina or they will begin to disappear leaving only small vestigial remains.  (The male reproductive organs develop out of the adjacent Wolffian duct.  These ducts begin to disappear during sex differentiation in females.)  Here is a diagram:

For reference, here is a list of homologous human reproductive structures (for instance, before sex differentiation, the scrotum and the labia majora are one and the same).

It is around this 8 week period that hormones are released from within a male fetus from the testes (from cells called Sertoli cells).  This is called the anti-Müllerian hormone.  The chromosomes of a male fetus receive this hormone and react by impeding the development of the Müllerian ducts.  In a female fetus, the chromosomes do not exist so the Müllerian ducts continue to develop.  From time to time, the necessary chromosome to inhibit the development of the Müllerian ducts in the male are missing.  (Remember that human chromosomes are incredibly complex, so when DNA is being “written” sometimes it can make a “typo.”)  When this happens, the fetus continues to develop the Müllerian ducts.  So, the genetically male fetus begins to grow a uterus and sometimes other female reproductive structures.  Usually, the testicles do not descend but a penis will still be present because it does not develop from the Müllerian ducts.  This is one of the many complications of determining sex at birth.  It may not be immediately clear what the child’s sex is.  This is called Persistent Müllerian duct syndrome (PMDS) and can also result as a failure of the testes to ever secrete the hormone.

So, going back to the words of my professor, all humans begin as embryos with the same “feminine” appearing genitalia.  This is why he says, with glee, that females are the prototypical humans.  Keep in mind all that the ancient Greek philosophers argued (and Freud, for that matter) that men were the essential human form and that women are defective versions of males.  Turns out, that all men start out as women in a manner.  There is a lot more to be said on this topic, but I will stop here for now.  Use the information you have learned here to impress your friends and put any obnoxious men in their place.  Please feel free to leave comments and questions.

Endometriosis

In the past two weeks, I cannot tell you how many times I have heard someone mention in conversation “endometriosis.” I have several friends and family members who have endometriosis, so it is not an altogether unfamiliar subject to me. However, I have never given much thought to endometriosis.   So, in writing this blog entry I hope to educate both myself and my readers a bit.

To start with the root, the word endometriosis comes from the Greek words meaning “inside” and “womb.”  Remember that the endometrium is the layer lining the uterus.  Here is a diagram:

The endometrium is where the embryo implants after it has been fertilized, so it is an integral part of reproducing.  Without a healthy endometrium, an embryo is not likely to implant successfully.

Interestingly, too many endometrial cells are a bad thing, and this is what endometriosis is:  the proliferation (spread) of endometrial cells outside of the uterus, especially common on the ovaries.  These cells respond as the endometrium does to hormonal changes over the course of a menstrual cycle.  So, imagine that you have endometrial cells throughout your pelvis and not just in your uterus.  Menstrual cramps would be amplified–the pain difficult to bear.  So, if you have particularly unmanageable menstrual pain during your period, please visit your doctor.  You may have a disorder such as endometriosis.  Only investigation by a medical professional can determine the source of the pain.

It is estimated that between 5-10 percent of women are affected by endometriosis.  Its effects generally do not manifest until menarche (first menstrual cycle) and usually diminish following menopause, though not always.  A large number of women who are infertile are infertile because of endometriosis (about 20-50%).  The proportion of women with chronic pelvic pain who suffer from endometriosis is much higher (about 80%).  There seems to be an increase in incidence of endometriosis in families that affected by it.  Women with an immediate relative with endometriosis has a higher risk of having endometriosis.  There is some association between endometriosis and certain types of cancer (especially ovarian), so it is important to know if you have endometriosis or if you have another malady with similar symptoms.

Endometriosis usually appears in patches within the pelvis that are often visible to the human eye during surgery because they can appear as darkened bluish-black spots.  Here is a diagram example of endometriosis:

Not all endometriosis appears as darkened spots, so it is necessary sometime to perform biopsies to be certain.  Endometriosis causes an inflammatory response that often causes scar tissue.  This scar tissue is frequently problematic in a variety of ways, including being the cause of infertility.  The cause of endometriosis is, so far, unknown but it is believed that there is more than one possible cause.  Hopefully, further research will uncover causes that can help in management and treatment of the disease.  Symptoms, too, can vary widely across endometriosis sufferers.  Abdominal pain being the most common symptom, others include:

  • nausea, vomiting, fainting, dizzy spells
  • frequent or constant menstrual flow
  • chronic fatigue
  • heavy or long uncontrollable menstrual periods with small or large blood clots
  • mood swings
  • pain in legs and thighs
  • back pain
  • mild to extreme pain during intercourse
  • mild to severe fever
  • headaches
  • depression
  • Again, it is important to remember that other disorders can have similar symptoms to endometriosis.  It is crucial to consult a doctor if you are experiencing problems in order to accurately determine what you have.  Never rely on an “Internet diagnosis.”  This article is just scratching the surface of this topic (maybe I will write “Endometriosis:  Part 2”), so please feel free to leave comments and questions!