The Reproductive Process Here we discuss the normal reproductive processes of the human male and female as you might find in a biology textbook. This information is intended as a source of reference to familiarize users with how the human body should be performing its reproductive functions. Any of these processes mentioned are subject to disorder in the infertile patient and are the primary focus of your infertility specialist in attempting to diagnose a potential anomaly. If the thought of a high school biology lesson makes you cringe or if you don’t care how normal people function – you want to know what’s wrong with you, feel free to press on to the methods of diagnosing infertility. Those of you continuing here will soon be able to amaze your friends with your knowledge of the reproductive process.   Female Reproductive Process The female reproductive process is deemed ultimately successful by the production of one or more mature eggs being released from the ovary (known as ovulation) and drawn in by the fallopian tubes where they await fertilization from a migrating sperm. The fertilized egg then continues traveling down the Fallopian tube until it reaches the uterus where it implants and ultimately forms a fetus. Seems easy enough, right? Not quite. Read that last paragraph one more time. There are a tremendous number of things that have to go just right during this process in order to achieve a viable pregnancy. Let’s break down the steps.   Step 1: Egg production and release from the ovary is regulated by two hormones, FSH and LH, which are produced by the pituitary gland located at the base of the brain. FSH is the primary hormone that stimulates the development of eggs within small sacs called follicles inside the ovary. Each month, several follicles can develop, with one typically maturing faster than the others (also see Ovarian Physiology in the Ovulation Induction section of this site for more specific details on this process). Once this dominant follicle has sufficiently matured, an LH surge causes the follicle to rupture, forcing the egg out onto the surface of the ovary. This is known as ovulation. Once the egg is released, we call the empty follicle by a new name – the corpus luteum. The corpus luteum produces a hormone called progesterone, which along with estrogen, helps the uterus prepare itself for the possibility of conception. Step 2: Hairlike projections called fimbriae located at the end of and inside the Fallopian tube draw the egg from the surface of the ovary into the tube. The fertilized egg must then make its way down the tube to the uterus. This step implies that the female has normal, patent fallopian tubes capable of supporting fertilization and embryonic development. See Tubal Factors under Diagnosing Infertility for information on the variety of tubal factors commonly associated with infertility. Step 3: Egg awaits fertilization from a sperm. This step assumes normal sperm function and no obstructions to prevent sperm from reaching the egg. See Anatomical Factors, Cervical Factors, and Male Infertility under Diagnosing Infertility for relevant information. Step 4: The fertilized egg must develop over the course of a week into a pre-implantation embryo. Egg, sperm and resulting embryo must be genetically competent to reach a pre-implantation state. See Embryology for information on embryo development and sources of attrition. Step 5: Pre-implantation embryo implants in the uterine lining, develops into a fetus, and can be carried to term. This step requires a competent, hospitable uterus and uterine lining to accept and maintain a pregnancy. See Uterine Factors under Diagnosing Infertility for information on uterine factors affecting fertility potential. After reading this, you may be wondering how any of us ever gets pregnant at all! Indeed, there are a number of hurdles to overcome, with each step the source of a potential fertility problem. All these things are going on inside your body, so how are you supposed to know which of these steps is of concern for you? The answer is, "You’re not!" Only your infertility specialist is qualified to identify and treat problems associated with the reproductive process. Male Reproductive Process The male reproductive process is comparatively much less interesting than the female one, pretty much focused on the singular act of sperm production. Less interesting, perhaps, but equally as important is the process known as spermatogenesis. Spermatogenesis begins at puberty in the male, with the process taking place in the testis (specifically within an extensive network of maze-like structures called seminiferous tubules). Interestingly, the same two hormones which control egg production in the female, FSH and LH, also directly affect male testicular function and spermatogenesis. LH triggers testosterone production in the seminiferous tubules and, along with FSH, regulates the production of sperm. Through a number of rather complicated (and frankly kind of boring) steps, immature sperm cells are created in the membranes of the seminiferous tubules. Here sperm cells continue to differentiate into haploid spermatids which are eventually released into the lumen of the seminiferous tubules as nearly functional sperm called spermatozoa. The spermatozoa are then transported through the epididymis to the ejaculatory duct, during which time they undergo the final stages of maturation. As the male becomes sexually aroused to the point of ejaculation, the mature sperm are forced from the epididymis through the vas deferens, where they combine with fluid contributed by the seminal vesicles and prostate and finally out through the urethra. If ejaculation occurs during coitus the semen is deposited into the vagina, where the sperm with normal motility and morphology leave the seminal fluid, penetrate the cervical mucus within about 10 minutes and navigate the cervical canal, uterus, and Fallopian tubes - all with the singular goal of finding an egg to fertilize or literally die trying. Of the millions of motile sperm that are deposited in the vagina, only a few hundred will even get close to having contact with an egg.