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!

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.)

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.

Hormonal Differences

If you are anything like me and read the medical headlines every day you have probably noticed in the past few weeks a spate of articles about how hormones can affect a person’s social behavior.  The first such article was a timely piece, considering the state of the economy, that argues that the length of a person’s ring finger in relation to his or her index finger is indicative of his or her responsiveness to testosterone in the womb, and thus this measure correlates with how well the person is suited to financial trading. (Oddly, the Washington Post categorizes this article under “Women’s Health.”)

Specifically, these researchers say, the longer one’s ring finger in relation to the index finger the more likely it is that this person will be successful at financial trading.  Scientists are hailing this as “completely new and novel in terms of showing how sex hormones impact the brain.”  (Though there have been other studies that argue that sex hormones in the womb influence sexual orientation and anorexia.)  The trials performed in this study only examined men.  While it is possible that this effect also influences such behavior in women, it is unlikely to affect women as often as men since women naturally have less testosterone than men.

However, another article came out on the heels of this study arguing that higher amounts of estrogen (as an effect from the womb) cause women to not only feel more attractive and be perceived as more attractive but also to cheat on their partners more often.  The study showed that women with high levels of estradiol, a type of estrogen, were more likely to “dress more provocatively and show more thrill-seeking behavior.”  Interestingly, the likelihood of cheating on a partner was shown to take the form of monogamous affairs rather than one-night stands.  These women with higher estradiol are generally more fertile and therefore are hypothesized to biologically be programmed to continually look for other, better mates.  One of the researchers said, “Our results are consistent with the possibility that highly fertile women are not easily satisfied by their long-term partners and are especially motivated to become acquainted with other, presumably more desirable, men.”

Prenatal hormones and their effects have been known for years to play a great role in sexual differentiation.  Levels of testosterone and other factors in the womb can contribute to an XY-karyotype (or genetic boy) being born as a phenotypical female (with the appearance of female genitalia).  Research is constantly discovering more along these lines, such as the perceived psychological differences between males and females (i. e., men are from Mars, women are from Venus), including cognitive performance.  In light of these discoveries, many people cling to the notion that many of these naturally occurring situations are, rather, a result of nurture (e. g., a woman who cheats on her partner does so because of the way she was reared).

So, what do you think about all of this?  I would love to hear any or all questions or comments.  Thanks!

Sperm

Sperm may seem an odd choice of subject for a “young woman’s guide to gynecology and obstetrics.”  But it is this last word, obstetrics, that makes sperm a good choice for an entry subject.  Arguably, without sperm, obstetrics would not exist.   This may not always be the case, but for the time being, each human pregnancy makes use of sperm somewhere in the process.  So, let’s talk about sperm, baby!

Sperm is the male counterpart to the female gamete, the ovum (or egg).  Technically, what we commonly refer to as a sperm should be considered more of a sperm cell called a spermatozoon (spermatozoa, plural).  Since virtually everyone refers to the spermatozoon as a sperm, I will continue to use the word sperm in its place.  The human sperm consists of, ostensibly, a head an a tail.  This simple-looking structure belies its key importance in creating life.  Stored within the sperm is a complex DNA code that will (usually)[1] determine the sex of the resultant child and influence its phenotypical appearance–short or tall, dark or light, thin or stout–and many other genetic factors.

Each sperm is about three micrometers at its widest and about fifty micrometers long.  The tail of the sperm powers it forward, almost like a propeller, at about 1 to 3 millimeters per minute.  The semen, the fluid in which sperm are expelled from the male, has a chemical balance that keeps the sperm mostly inert until it is neutralized by the acidic environment of a vagina.  The sperm, when entering the vagina, journey upward in search of an egg to fertilize.  If the sperm do find an egg they will attempt to penetrate the membrane.  A single  sperm will succeed in penetrating the egg and the fusion of the two begins the process of meiosis in which the DNA of the mother and the father are spliced together to form a new set of DNA.

At this point, the sperm has reached its goal and blends into the developing human.  However, the sperm has many variations and not all sperm conform to the usual model we have in mind.  Abnormal sperm are actually quite common and come in many varieties.  For example, there are sperm with two heads, two tails, both, neither, and various other extra and missing parts.  Most abnormally structured sperm do not pose a genetic complication or threat to a potential pregnancy.  Because of structural deficiencies these abnormal sperm are not likely to reach an egg in the first place.

In all, sperm are an interesting and integral part to creating life and without them, there would be little basis for obstetrics.  So, any time you are thinking about obstetrics keep in mind the “little swimmers” that help make it possible.  Comments, questions, otherwise?  Please bring them forward!

[1] I am careful to say that the sperm usually determines the sex of a child because certain genetic problems can preclude a child with XY sex chromosomes from developing male characteristics, including genitalia, thus the Y-sperm from the father in this case does not determine the sex of the child.

History of the IUD

Speaking of Dr. Ernst Gräfenberg, let’s talk about intrauterine devices (IUDs) since Dr. G is recognized as the first developer of the modern IUD.  IUDs, in a crude sense, have existed for an untold number of years.  Women and men have inserted various implements into human and animal uteri to prevent pregnancy for many years.  Forerunners to the modern IUD emerged in the beginning of the twentieth century with inventions such as the stem pessary.

The first true modern IUD was invented in the late 1920s by Dr. Gräfenberg when he was still practicing gynecology in Germany.  The IUD that Dr. G invented was, instead of the familiar t-shaped device, actually a circle-shaped device:  the Gräfenberg ring.  These rings were silk threads covered with fine silver wire.  The metal of this device caused an inflammatory response in the uterus thus creating hostile conditions for sperm.  He later found that some copper mixed with the silver aided in the contraceptive ability of the device.  (Of course, for a number of uteri in which these were inserted the inflammation was so great as to cause complications, though these were rarely severe.)  By the end of the 1930s, the Gräfenberg ring fell out of use mostly because of the eugenic policies implemented by Nazi Germany (in which all contraception was outlawed, as it was in Japan as well).  Gräfenberg himself left Germany in 1937 to escape persecution because of his Jewish heritage.

The modern plastic-based IUD began to take shape in the United States in the 1950s.  Lazar C. Margulies, an obstetrician in New York, is generally credited for pioneering plastic IUDs to help reduce the danger associated with previous IUDs.  In 1958 he introduced his version of the IUD, though it was not greatly successful because of its large size.  In 1962, Jack Lippes, a gynecologist also in New York, developed a smaller, plastic IUD that became more popular.  In the late 1960s, Howard Tatum, another New York obstetrician, developed a plastic-cased, cooper-based IUD that could be dramatically reduced in size without sacrifcing its effectiveness.  During the 1970s, in an effort to help cheaply curb reproduction and enforce the “one-child policy,” Chinese physicians developed the stainless-steel IUD, but banned them by early 1990s because of a 10% pregnancy rate due to steel’s lowered contraceptive capability.

The second generation of plastic-copper IUDs came around in the 1970s.  These IUDs increased the surface area of the devices and increased their effectiveness above 99%.  Today, in the United States, this type of IUD and one other type are available.  The copper IUD available in the United States is called ParaGuard and is effective for twelve years.  The other type of IUD available in the United States is a hormone-based IUD, called Mirena, that functions in a few ways.  This IUD first creates a hostile environment for sperm, much like copper-IUDs by thinning the uterine lining making it highly unlikely a fertilized egg could implant in the uterus.  Second, the hormones involved create a thicker cervical plug making it less likely that sperm will enter the uterus to begin with.  Finally, the hormone-IUD in some instances stops the ovary from releasing an egg, though this is less likely than the other two functions.  Hormone-based IUDs were developed in the 1970s, but have not been popular in the United States until recently because of ad campaigns for Mirena (though they remain relatively very unpopular compared to condoms and the pill).

This is all a sort of background to understanding the IUD.  Hopefully, in a later entry we can better address the scientific and medical aspects of IUDs in their modern form.  Do you have something to say about IUDs?  Or anything else?  I yield the floor.

Crabs: What Are They?

In school growing up there were numerous crab jokes made by my classmates.  If we wanted to give the ultimate insult we would say, “S/he’s got crabs.”  Of course, we didn’t really know what crabs were.  We knew vaguely they were something one acquired in the genital region generally from a sexual encounter and are considered embarrassing.  So, let’s delve into the question:  what are crabs?

The scientific name for what is generally referred to as a “crab” is phthirus pubis (pronounced how it looks, I’m sure).  It is also referred to as pubic louse or crab louse, named so for its slight resemblance to crabs.  (Remember, too, that the word “cancer” comes from the Latin word for crab, via the Greek carcinoma also meaning crab.  What’s up with that?)  These lice are actually insect parasites that feed entirely on blood and live on human hairs.  Pubic lice are a different species than body lice and head lice.  They are whitish-gray in color, though are temporarily reddish after feeding.  They are usually 1-2 millimeters in size, with females being larger than males for the purpose of producing eggs.

Pubic lice, in spite of their name, can infest more than just the pubic region.  Though they are most often found in the pubic region they can also be found in hair on the abdomen, under the arms, in beards and mustaches, as well as eyelashes and eyebrows.  Crabs, if you will, are most often transmitted between hosts through close physical contact, i. e. sex.  However, they can be transferred between family members or roommates who share towels, beddings, or clothes.  Rarely, pubic lice can be acquired from public toilet seats, though this is very unlikely.  Crabs are more commonly found among adults, though they can be found among children.

Symptoms of a pubic lice infection include itching in the pubic region, visible nits or lice, lesions due to bites, and sometimes secondary infection of the bite-induced lesions.  Pubic lice can be diagnosed by a healthcare professional by visual examination and may further review a found louse under a microscope to confirm its species (pubic, body, or head louse).  Treatment consists of a treatment shampoo or wash that contains chemicals such as pyrethrins and piperonyl butoxide followed by combing to remove remaining nits.  These treatments are available over-the-counter.  For extreme infestations that persist following treatment, a prescription of lidane shampoo may be necessary.

Pubic lice are usually easily cured, though they will not go away on their own.  If pubic lice are found it is prudent to be tested for other sexually transmitted diseases, as most transmissions of crabs are through unprotected, non-monogamous sex.  Shaved or waxed pubic areas may help prevent infestations of crabs but will not stop all crabs.  Shaving already infested pubic hair will not stop the infestation.

So, did you learn anything new?  Maybe, maybe not.  Either way, I hope you can avoid acquiring pubic lice.  Questions or comments?  Spill the beans.