The prostate gland, about the size of a walnut, surrounds the urethra just below the bladder. During ejaculation, peristaltic contractions in the vas deferens propel sperm forward with surprising speed. Without this crucial maturation process, sperm would remain functionally inert. A healthy man can produce millions of sperm per day, a testament to the reproductive system’s staggering productivity. Between the tubules are Leydig cells, which produce testosterone. Scrotum Many diseases can make it more difficult to have an erection because of their impact on blood flow to your penis and other factors. If you have not been circumcised, pull back your foreskin, then clean and dry the head of your penis. Recommendations differ depending on your sexual practices and who you have sex with. There's plenty that you can do to keep your reproductive system working normally throughout your life. The accessory sex glands, including the seminal, prostate glands, and bulbourethral glands, produce seminal fluid and clean and lubricate the urethra. The ductus (vas) deferens, also called the sperm duct, extend from the epididymis on each side of the scrotum into the abdominal cavity through the inguinal canal, an opening in the abdominal wall for the spermatic cord. The prostate as well as the bulbourethral glands add further secretions, then the semen is expelled through the penis. Fluids are added by the seminal vesicles before the vas deferens carries the sperm to the ejaculatory ducts, which join the urethra inside the prostate gland. They include the vas deferens, seminal vesicles, prostate gland, and bulbourethral (Cowper’s) glands. Understanding these homologues helps illustrate the common developmental pathways that underlie the reproductive systems in both sexes. Each ductus deferens extends superiorly into the abdominal cavity through the inguinal canal in the abdominal wall. This procedure is called a vasectomy, and it is an effective form of birth control. Internal parts are inside your body, and external parts are outside your body. Key Structures They are curled and folded within the gland and can spread out to approximately 5 cm, but the unfolded length is approximately 10 cm. A modern procedure that does not include cutting the ducts involves injecting an obstructive material into the ductus to block the flow of sperm. The procedure of deferentectomy, also known as a vasectomy, is a method of contraception in which the vas deferens are permanently cut, though in some cases it can be reversed. The smooth muscle layer of the vas deferens contracts in waves of peristalsis during ejaculation. This results in an increase in the concentration of luminal sperm. Though the epididymis does not take up much room in its tightly coiled state, it would be approximately 6 m (20 feet) long if straightened. Sperm cells are divided into a head, containing DNA; a mid-piece, containing mitochondria; and a tail, providing motility. The central strand of the flagellum, the axial filament, is formed from one centriole inside the maturing sperm cell during the final stages of spermatogenesis. ATP produced by these mitochondria will power the flagellum, which extends from the neck and the mid-piece through the tail of the sperm, enabling it to move the entire sperm cell. Erectile dysfunction (ED) is a condition in which a man has difficulty either initiating or maintaining an erection. Depending on the flaccid dimensions of a penis, it can increase in size slightly or greatly during erection, with the average length of an erect penis measuring approximately 15 cm. The result of this increased blood flow to the penis and reduced blood return from the penis is erection. The rapid increase in blood volume fills the erectile chambers, and the increased pressure of the filled chambers compresses the thin-walled penile venules, preventing venous drainage of the penis. The function of your external genitals are to protect the internal parts from infection and allow sperm to enter your vagina. During intercourse, this area is lubricated by mucus secreted by the Bartholin’s glands. This may be an evolutionary adaptation to expel the semen left by other males while at the same time increasing the possibility of fertilization with the current male’s semen. When it’s cold, the scrotum contracts and wrinkles, pulling the testes closer to preserve heat.The function of the male reproductive system is to produce sperm and transfer them to the female reproductive tract.Special muscles in the wall of your scrotum let it contract (tighten) and relax.The inner part, attached to the bony margins of the pubic arch (that part of the pelvis directly in front and at the base of the trunk), is called the root of the penis.Your bulbourethral glands are pea-sized structures on the sides of your urethra, just below your prostate.Many people think of their external organs, which include their penis, scrotum and testicles.Doctors, nutritionists, and formulators reveal which testosterone booster supplements are best for men.Distinguish among the parts and functions of the male reproductive system As they are moved along the length of the epididymis, the sperm further mature and acquire the ability to move on their own. During the seventh month of the developmental period of a fetus secreting testosterone, each testis moves through the abdominal musculature to descend into the scrotal cavity. The testes are spherical in shape, each approximately 4 to 5 cm in length and are housed within the scrotum (see Figure 84.7). The skin of the glans of a circumcised penis converts from a mucous membrane to a cutaneous membrane, and the friction reducing function of the foreskin is lost. The end of the penis, called the glans penis, has a high concentration of nerve endings, however not as dense and therefore not as sensitive as the glans clitoris (see Figure 84.5). Once inside the female reproductive tract, they will use this ability to move independently toward the unfertilized egg. Approximately 100 to 300 million sperm are produced each day, whereas women typically ovulate only one oocyte per month as is true for most cells in the body, the structure of sperm cells speaks to their function. Eventually, the sperm are released into the lumen and are moved along a series of ducts in the testis toward a structure called the epididymis for the next step of sperm maturation. This is called the “descent of the testis.” Cryptorchidism is the clinical term used when one or both of the testes fail to descend into the scrotum prior to birth. What are the functions of the female reproductive system? Both sexes have what's called a cloaca — it's a single orifice used for waste and reproduction. Most birds, on the other hand, don't have penises or vaginas. Male kangaroos have a two-pronged penis to inseminate the lateral vaginas. The two lateral vaginas are used for accepting sperm during mating, and the central vagina is used for birthing. Until the late 17th century and early 18th century, physicians held to the "one-sex" reproductive model of thinking, which was championed by Greek physician Galen of Pergamon almost 2,000 years ago. The epididymis is a coiled structure consisting of a head, body, and tail.Not only does the tunica albuginea cover the outside of the testis, it also invaginates to form septa that divide the testis into 300 to 400 structures called lobules.The enzyme 17-beta-hydroxysteroid dehydrogenase completes the conversion of androstenedione to testosterone.These cells are characterized by their relation to germ cells or primitive spermatogonia.The testicular artery provides the blood supply to the testes, while the pampiniform plexus of veins functions in venous return from the testes.The external muscular sac responsible for holding the testes, located posterior to the penisThe human penis cannot be withdrawn into the groin, andis larger than that of any other primate, particularly in regards to proportion to body mass.Sometimes children are labeled as male or female, depending on how complete or functional one sexual reproductive system is over the other.The former are the convoluted seminiferous tubules and rete testis, and the latter are Leydig and Sertoli cells. While the reduction in sex steroids in men is akin to female menopause, there is no clear sign—such as a lack of a menstrual period—to denote the initiation of andropause. The resulting reduction in circulating testosterone concentrations can lead to symptoms of andropause, also known as male menopause. These polypeptide hormones correlate directly with Sertoli cell function and sperm number; inhibin B can be used as a marker of spermatogenic activity. In men, FSH binds predominantly to the Sertoli cells within the seminiferous tubules to promote spermatogenesis. These two hormones are critical for reproductive function in both men and women. Clinical significance The bulbourethral glands are relatively small and often overlooked, but they can play an important role in male reproductive health.Some of the clinical conditions that affect the spermatic cord include testicular torsion, inguinal hernia, epididymitis, and varicocele.There are lots of different combinations of body parts and hormones that fall under the intersex umbrella.It contributes enzymes and a slightly milky fluid to semen that enhances sperm motility and longevity.Some humans are born with parts of both male and female reproductive systems or incomplete reproductive organs of one sex or the other.It’s also where your sexual fantasies and identities are.These cells are located in the interstitial tissue of the testes, also known as the Leydig cell zone.There's plenty that you can do to keep your reproductive system working normally throughout your life.Most people have two testicles, on the left and right side of their scrotum. This results in two cells, called secondary spermatocytes, each with only half the number of chromosomes. By contracting simultaneously, the dartos and cremaster muscles can elevate the testes in cold weather (or water), moving the testes closer to the body and decreasing the surface area of the scrotum to retain heat. Women and those assigned female at birth of reproductive age experience cycles of hormonal activity that repeat about every month. Both hormones come from the same glycoprotein family and consist of identical alpha subunits, but their different beta-subunit differentiates their functions. GnRH is inhibited by testosterone, estrogen, estradiol, and prolactin. Secondary sexual characteristics such as facial, axillary, chest and pubic hair growth, deepening of the voice and growth spurt occur next. They produce testosterone, a hormone that is responsible for the development of male secondary sexual characteristics and the stimulation of sperm production. They are also the primary source of testosterone, the hormone that regulates male sexual development and function. The urethral meatus is an important part of the male reproductive system as it allows for the release of semen during ejaculation. Within the prostate, the urethra coming from the bladder is called the prostatic urethra and merges with the two ejaculatory ducts. The thick seminal vesicle secretions contain proteins (including enzymes), mucus, fructose, vitamin C, flavins, phosphorylcholine, and prostaglandins. It may be a developmental rest, such as in some rodents where the last part of the ejaculate forms a spermicidal plug to reduce the chances for sperm from a later-arriving male to proceed to the oocyte. Thus, the exact physiological importance of seminal vesicular fluid is unclear. The human body is a symphony of motion, sensation, emotion, and thought. These may include low sperm count, poor motility, structural abnormalities, or genetic disorders. Infertility affects around 10–15% of couples, and in about half of cases, male factors are involved. BPH causes urinary difficulties due to prostate enlargement, while prostate cancer is a leading cancer among men, often detected by elevated PSA levels or digital rectal exams. Prostate issues, including benign prostatic hyperplasia (BPH) and prostate cancer, become more common with age. These spermatozoa are still immotile and are released into the tubules to travel to the epididymis for maturation.The urethra is surrounded by the corpus spongiosum, one of the cylindrical spaces of the soft tissue of the penis described earlier.The hypothalamus and pituitary gland regulate the production of testosterone and the cells that assist in spermatogenesis.Most people have either a penis and scrotum or a vulva, but each person’s genitals are uniquely their own.During ejaculation, sperm exit the tail of the epididymis and are pushed by smooth muscle contraction to the ductus deferens (also called the vas deferens).The testis is the location for testosterone production.The principal functions of these structures are to transport the spermatozoa from the testes to the exterior, to allow their maturation on the way, and to provide certain secretions that help form the semen.This may be an evolutionary adaptation to expel the semen left by other males while at the same time increasing the possibility of fertilization with the current male’s semen.The female reproductive system contains organs inside and outside the body. Gonocytes divide rapidly in the fetal testes, giving rise to a population of germ cells that will eventually become spermatozoa. Germ cells These are the type of cell that gives rise to spermatozoa or ova, the reproductive cells that allow for the transmission of genetic information from one generation to the next. They produce testosterone, a hormone that is responsible for the development of male secondary sexual characteristics such as muscle mass, facial hair, and a deeper voice. Pubic hair is a type of hair that grows in the pubic area and is an important part of the male reproductive system. Ejaculation is the ejection of semen from the penis and is usually accompanied by orgasm. An erection is the stiffening and rising of the penis that facilitates sexual arousal, though it can also happen in nonsexual situations. It is located on the ventral aspect of the penis and runs from the meatus and across the scrotum to the perineum (area between scrotum and anus). Sperm are produced in the testes and stored in the attached epididymis. These are narrow tubes that are attached to the upper part of the uterus and serve as tunnels for the ova (egg cells) to travel from the ovaries to the uterus. A channel through the cervix allows sperm to enter and menstrual blood to exit. The vagina is a canal that joins the cervix (the lower part of the uterus) to the outside of the body. Like the penis, the clitoris is very sensitive to stimulation and can become erect. Hence, loss of testicular function results in damaged or underdeveloped Leydig or Sertoli cells that cannot respond to stimuli to maintain reproductive function.Unique for its role in human reproduction, a gamete is a specialized sex cell carrying 23 chromosomes—one half the number in body cells.The portion of the uterus superior to the opening of the uterine tubes is called the fundus.That means the Parasympathetic innervation is involved in the erectile function (point), while the Sympathetic innervation is involved in ejaculation (shoot).The hypothalamus and the pituitary gland in the brain integrate external and internal signals to control testosterone synthesis and secretion.The seminiferous tubules produce sperm cells through spermatogenesis.The internal body systems of animals are often similar to ours, but there's a remarkable variation in reproductive systems in the animal kingdom.It consists of several internal and external organs that work together to produce, store, and transport sperm. Seminal Vesicles and Prostate Gland: Makers of Semen Despite their small size, the bulbourethral glands play a crucial role in the male reproductive system by producing a lubricating fluid that is essential for successful sexual intercourse. The male reproductive system includes external (penis, scrotum, epididymus, and testes) and internal (accessory) organs. View our diagram of the male reproductive organs, including the penis, testicles, prostate, urethra and vas deferens. Epididymis Describe the function of testes and the development of sperm The purpose of the scrotum is to provide the testes with a chamber of appropriate temperature for optimal sperm production. Special muscles in the wall of the scrotum contract and relax in order to move the testes near the body. For sperm development, the testes must maintain a temperature slightly cooler than normal body temperature. The scrotum has a protective function, including the maintenance of optimal temperatures for sperm survival and function. These tubules are lined with specialized cells that nurture developing sperm cells and facilitate their transformation from primitive germ cells to motile, mature spermatozoa. Inside each testis are seminiferous tubules, tightly coiled structures where spermatogenesis (sperm production) takes place. When it’s cold, the scrotum contracts and wrinkles, pulling the testes closer to preserve heat. Keeping your reproductive system healthy sometimes means asking your doctor for help.The epididymis is made up of several feet of long, thin tubules that are tightly coiled into a small mass.The testis is homologous to the ovary in that it produces the male gamete (sperm) while the ovary produces the female gamete (egg).A modern procedure that does not include cutting the ducts involves injecting an obstructive material into the ductus to block the flow of sperm.These structures are well-vascularized with many glands and ducts to promote the formation, storage, and ejaculation of sperm for fertilization, and to produce important androgens for male development.Treatment for prostate cancer depends on the age, severity of the disease and other health conditions of the patient.Infertility affects around 10–15% of couples, and in about half of cases, male factors are involved.The ductus deferens is a thick, muscular tube that is bundled together inside the scrotum with connective tissue, blood vessels, and nerves into a structure called the spermatic cord (see Figure 27.2 and Figure 27.3). Male reproductive system - myDr.com.au The continued presence of testosterone is necessary to keep the male reproductive system working properly, and Leydig cells produce approximately 6 to 7 mg of testosterone per day. When erect, the stiffness of the organ allows it to penetrate into the vagina and deposit semen into the female reproductive tract. Sperm are smaller than most cells in the body; in fact, the volume of a sperm cell is 85,000 times less than that of the female gamete. This dilation increases the amount of blood that can enter the penis and induces the endothelial cells in the penile arterial walls to also secrete NO and perpetuate the vasodilation.The length of the epididymis delays the release of the sperm and allows them time to mature.The second category, the ejaculatory fluid-producing glands, includes the seminal vesicles, prostate, and vas deferens.Offspring are produced by the fusion of gametes (sex cells) from each parent.This fluid is milky white in color and contains enzymes, proteins, and other chemicals to support and protect sperm during ejaculation.Approximately 100 to 300 million sperm are produced each day, whereas women typically ovulate only one oocyte per month as is true for most cells in the body, the structure of sperm cells speaks to their function.Tiny muscles called the dartos and cremaster regulate this movement with incredible precision. The spermatozoa are released into the epididymis where they complete their maturation and become able to move on their own. The spermatid cells then go through a process known as spermiogenesis where they grow a flagellum and develop the structures of the sperm head. The secondary spermatocytes go through meiosis II to form 4 haploid spermatid cells. The prostate also contains smooth muscle tissue that can constrict to prevent the flow of urine or semen. This fluid is milky white in color and contains enzymes, proteins, and other chemicals to support and protect sperm during ejaculation. The outer layer is the external spermatic fascia, a continuation of the external oblique muscle aponeurosis that covers the entire length of the cord. The cord contains three layers of tissue that envelop its contents, including the vas deferens, testicular artery, veins, lymphatics, and nerves. Their secretions play a crucial role in lubricating the urethra, neutralizing acidic urine, and enhancing sexual pleasure. The amount of fluid produced can vary widely between individuals, but on average it is estimated to be between 0.1 and 0.5 milliliters. Regulation The secretion of the bulbourethral fluid is regulated by the parasympathetic nervous system. The epididymis is a sperm storage area that wraps around the superior and posterior edge of the testes. Each testis is found inside its own pouch on one side of the scrotum and is connected to the abdomen by a spermatic cord and cremaster muscle. The testes are ellipsoid glandular organs around 1.5 to 2 inches long and an inch in diameter. Males may be able to make sperm well into their 80s or even longer. In males, the testicles don’t lose the ability to make hormones. Menopause is when the ovaries stop making reproductive hormones. This fluid lubricates your urethra and neutralizes any acids that may remain from your pee. They create a clear, slippery fluid that empties directly into your urethra. Most females will have a menstrual period 10 to 16 days after ovulation.This means you are not able to impregnate your female partner despite having regular, unprotected sex for at least a year.This arrangement indicates the bilateral origin of the scrotum from two genital swellings that lie one on each side of the base of the phallus, the precursor of the penis or clitoris in the embryo.They also support libido, spermatogenesis, and erectile function.Other tests include blood prostate-specific antigen test (PSA), which screens for prostate cancer.Sertoli cells are a type of supporting cell called a sustentacular cell, or sustenocyte, that are typically found in epithelial tissue.It provides a cushion and protection for the external genitalia and helps to reduce friction during sexual activity.Inside each testis are seminiferous tubules, tightly coiled structures where spermatogenesis (sperm production) takes place. Everyone’s reproductive and sexual anatomy looks a little different. Interplay between the testes and the endocrine system precisely control the production of testosterone with a negative feedback loop. Upon release from the seminiferous tubules, sperm are moved to the epididymis where they continue to mature. Spermatogenesis begins with mitotic division of spermatogonia (stem cells) to produce primary spermatocytes that undergo the two divisions of meiosis to become secondary spermatocytes, then the haploid spermatids. Spermatogenesis, the production of sperm, occurs within the seminiferous tubules that make up most of the testis. Reproductive and sexual anatomy (also known as sex anatomy) includes the sex organs on the outside of your body and the sex and reproductive organs on the inside of your body. During ejaculation, sperm exit the epididymis through the ductus deferens, a duct in the spermatic cord that leaves the scrotum. FSH also stimulates the Sertoli cells to produce hormones called inhibins, which function to inhibit FSH release from the pituitary, thus reducing testosterone secretion. Some people are born with missing or irregularly-shaped reproductive organs. Everyone’s reproductive organs look slightly different. There are two kinds of sex cells — sperm and eggs. Most females will have a menstrual period 10 to 16 days after ovulation. There are four major hormones (chemicals that stimulate or regulate the activity of cells or organs) involved in the menstrual cycle. For human beings, the temperature should be one or two degrees Celsius below body temperature (around 35 degrees Celsius or 95 degrees Fahrenheit); higher temperatures may be damaging to sperm count. The left testis is usually lower than the right, which may function to avoid compression in the event of impact. In humans and some other mammals, increased testosterone secretion during puberty causes the darkening of the skin and development of pubic hair on the scrotum. The testis is the location for testosterone production. The epididymus is located at the back of the testis and connects it to the vas deferens. The scrotum is the muscular sac that holds the testes outside of the body cavity. In the testis, LH binds to LH receptors on Leydig cells and stimulates the release of testosterone. In men, LH binds to receptors on Leydig cells in the testes and upregulates the production of testosterone. A small amount of testosterone is also secreted by the adrenal glands in both sexes. The intricate interplay between the endocrine system and the reproductive system is shown in Figure 27.8. Approximately 100 to 300 million sperm are produced each day, whereas women typically ovulate only one oocyte per month. Now a second round of cell division (meiosis II) occurs in both of the secondary spermatocytes. The seminiferous tubules produce sperm cells through spermatogenesis. Your testicles make testosterone and produce sperm. Your scrotum contracts to move your testicles closer to your body for warmth and protection. Your scrotum is the loose, pouch-like sac of skin that hangs behind your penis. The internal organs of the male reproductive system are called accessory organs. The fluid is also alkaline, helping to neutralize the acidic environment of the female reproductive tract. Other tests include semen analysis, which establishes fertility status and function of the seminiferous tubules, epididymis, and accessory sex glands. Common tests of male reproductive function include a blood test to measure testosterone levels. Finally, the pre-ejaculate can also help to enhance sexual pleasure by reducing friction during intercourse. The root of the penis is attached to the pelvic bone and the shaft is the long, cylindrical part of the penis. I support clients struggling with sexual disorders, relationship conflicts, anxiety, emotional regulation, and adolescent concerns. This duct is approximately 2.5 cm long and opens into the urethra at the base of the penis. The prostate is sheathed in the muscles of the pelvic floor, which contract during the ejaculatory process. These spermatocytes undergo meiosis I to produce haploid secondary spermatocytes, which undergo meiosis II to form haploid spermatids. The first stage of spermatogenesis begins with mitosis of diploid spermatogonia into primary spermatocytes. One cycle of spermatogenesis begins approximately every 13 days; however, spermatogenesis is not consistently synchronous throughout all seminiferous tubules. Specifically, the zona reticularis of the adrenal medulla is responsible for generating the weak androgens DHEA and androstenedione, which go on to be converted to testosterone or estradiol peripherally. In the third decade of life, testosterone levels are found to decline. Anatomy The bulbourethral glands are located on either side of the urethra, just below the prostate gland. The bulbourethral glands, also known as Cowper's glands, are two small glands located at the base of the penis. The penis is responsible for transferring semen from the body during ejaculation. The scrotum, which houses the testes, helps to regulate their temperature for proper sperm production. Bulbourethral glands are located posterior and lateral to the membranous portion of the urethra at the base of the penis, between the two layers of the fascia of the urogenital diaphragm in the deep perineal pouch. Your scrotum is the loose, pouch-like sac of skin that hangs behind your penis.Descending from the internal oblique muscle of the abdominal wall are the two cremaster muscles, which cover each testis like a muscular net.I support clients struggling with sexual disorders, relationship conflicts, anxiety, emotional regulation, and adolescent concerns.The entire male reproductive system depends on hormones.The testes are located in a skin-covered, highly pigmented, muscular sack called the scrotum that extends from the body behind the penis (see Figure 27.2).These are relatively large and fleshy and are comparable to the scrotum in males.In male embryos, testosterone is secreted by Leydig cells by the seventh week of development, with peak concentrations reached in the second trimester.The continued presence of testosterone is necessary to keep the male reproductive system working properly, and Leydig cells produce approximately 6 to 7 mg of testosterone per day. The seminal vesicles are small glands located near the base of the bladder that produce a thick, nutritious fluid that mixes with sperm to form semen. Leydig cells are the primary source of testosterone in males and play a crucial role in the development and maintenance of male reproductive function. The testes, also known as testicles, are the primary male reproductive organs responsible for producing and storing sperm. Although the glands are typically healthy and function normally, they can be subject to a variety of conditions that can affect male reproductive health. The male reproductive system is the system responsible for producing and transporting sperm and semen, as well as the delivery of sperm during sexual intercourse. Although a majority of testosterone production in men come from the Leydig cells in testes, the adrenal cortex contributes some androgen production. FSH and testosterone can stimulate Sertoli cells to release androgen-binding protein (ABP), which provides testosterone to germ cells during spermatogenesis. LH stimulates Leydig cells in the interstitium of the testes to produce testosterone from cholesterol. Understanding the structure, function, and regulation of Leydig cells is important for the diagnosis and treatment of male reproductive disorders. Leydig cells play a crucial role in the development and maintenance of male reproductive function. Function of Leydig Cells Leydig cells play a vital role in the development and maintenance of male reproductive function. Spermatic cord The spermatic cord is an essential anatomical structure in the male reproductive system, comprising multiple components, including blood vessels, nerves, lymphatics, and the vas deferens. They continue to grow, and at puberty their activity increases and maturation occurs, enabling sexual reproduction. The activity of the ovaries and uterus goes through a monthly cycle of changes (see menstruation) throughout the reproductive years except during pregnancy and nursing. Human reproductive system, Organ system by which humans reproduce. There are lots of different combinations of body parts and hormones that fall under the intersex umbrella. It’s also where your sexual fantasies and identities are. At puberty, spermatogenesis begins when luteinizing hormone (LH) and follicle stimulating hormone (FSH) are produced. Prior to puberty, there is no spermatogenesis due to the lack of hormonal triggers. The erection of the penis causes it to increase in size and become turgid. Large pockets of erectile tissue in the penis allow it to fill with blood and become erect. Together, these hormones promote puberty and subsequent maintenance of the male reproductive system. However, having the Y chromosome defines differentiation into the male phenotype and the male reproductive system. Together, these hormones form the hypothalamic-pituitary-gonadal axis that promotes and maintains sexual development and function in the male. Test your knowledge of the male reproductive system with this quiz. The spermatic cord conveys the neurovascular bundle of the testes and suspends them in the scrotum. Seminal vesicle fluid is alkaline, resulting in human semen with a mildly alkaline pH. This helps neutralize the acidity of the vaginal tract, prolonging the lifespan of sperm. About 50–70% of seminal fluid in humans originates from the seminal vesicles, but is not expelled in the first ejaculate fractions which are dominated by spermatozoa and zinc-rich prostatic fluid. The seminal vesicles secrete a significant proportion of the fluid that ultimately becomes semen. The inner part, attached to the bony margins of the pubic arch (that part of the pelvis directly in front and at the base of the trunk), is called the root of the penis. Your external reproductive organs might look different than someone else’s, and it’s natural for them to change slightly over time. However, replacing male hormones can make prostate cancer worse. External male reproductive organs There are external organs (including the penis, scrotum, and testicles) and internal organs (including the urethra and prostrate gland). The male reproductive system also produces hormones such as testosterone, which play a key role in male development. The principal functions of these structures are to transport the spermatozoa from the testes to the exterior, to allow their maturation on the way, and to provide certain secretions that help form the semen. The male gonads are the testes; they are the source of spermatozoa and also of male sex hormones called androgens. These increase the risk for pelvic inflammatory disease (PID), infection of the uterine tubes or other reproductive organs. The cervix opens into the vaginal cavity via the os, which allows the fluid to move through the vagina and exit the body through the vaginal opening. An intact hymen cannot be used as an indication of “virginity”; even at birth, this is only a partial membrane, as menstrual fluid and other secretions must be able to exit the body. The sperm released during ejaculation must first swim through the vagina and uterus and into the fallopian tubes where they may find an oocyte. Fertilization is the process by which a sperm combines with an oocyte, or egg cell, to produce a fertilized zygote. After spermiogenesis, the cell is finally a sperm cell, or spermatozoa. Each diploid spermatocyte goes through the process of meiosis I and splits into 2 haploid secondary spermatocytes.