Finally, the full-length form of ERα has been detected in purified rat germ cells, using a specific antibody directed against the C-terminal region of the protein (70) (Table 3). This peculiar distribution explains several important estrogen actions in the proximal ducts, especially within the efferent ductules that are small and convoluted tubules connecting the rete testis (an anastomosing network of intricate and tenuous tubules located in the hilum of the testis) to the epididymis (60). A recent study suggests that estradiol is also able to increase the production of stem cell factors by fetal human Sertoli cells, finally resulting in the proliferation and growth of spermatogonial stem cells (62). Your two vasa deferentia (plural) are part of the male reproductive system. Typically, you have a vas deferens (also called a sperm duct or a ductus deferens) in each testicle. Testosterone is made in the interstitial cells of the testes. Differentiate among the hormones of the male reproductive system GnRH activates the anterior pituitary to produce LH and FSH, which in turn stimulate Leydig cells and Sertoli cells, respectively. Testosterone, an androgen, is a steroid hormone produced by Leydig cells. The end of the penis, called the glans penis, has a high concentration of nerve endings, resulting in very sensitive skin that influences the likelihood of ejaculation. As shown in Figure 1, the centrally located prostate gland sits anterior to the rectum at the base of the bladder surrounding the prostatic urethra (the portion of the urethra that runs within the prostate). If sperm do not exit through the vas, either because the man has had a vasectomy or has not ejaculated, in what region of the testis do they remain? The male reproductive system includes external (penis, scrotum, epididymus, and testes) and internal (accessory) organs. These sperm cells fertilize oocytes inside the female fallopian tubes. In healthy adult males, semen contains around 100 million sperm cells per milliliter. 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. The more mature sperm are then stored in the tail of the epididymis (the final section) until ejaculation occurs. The bulbourethral glands (also known as Cowper’s glands) are a pair of pea shaped exocrine glands located posterolateral to the membranous urethra. At the beginning of the glans penis, a circular fold of skin, commonly called the foreskin (or prepuce), extends forward to cover the glans. The skin, which is slightly darker in colour than the rest of the body, is loose and folded while the penis is in a flaccid state. Female reproductive organs The ductus deferens delivers the sperm to ejaculatory duct by joining with the seminal vesicle duct near the prostate. 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. Testosterone can also exert some effect on Sertoli cells, found in the periphery of the seminiferous tubules of testes. LH stimulates Leydig cells in the interstitium of the testes to produce testosterone from cholesterol. Oogonia ovarian stem cells that undergo mitosis during female fetal development to form primary oocytes Whereas the breasts are located far from the other female reproductive organs, they are considered accessory organs of the female reproductive system. The external female reproductive structures are referred to collectively as the vulva (Figure 27.10). 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. It is an extension of the perineum, and is located between the penis and anus. Paired ovals, the testes are each approximately 4 to 5 cm in length and are housed within the scrotum (see Figure 27.3). The intricate interplay between the endocrine system and the reproductive system is shown in Figure 27.8. • The more frequently an individual stallion is collected the lower will be his semen volume. Frequency of ejaculation will affect total volume and number of spermatozoa per ejaculate until the daily sperm output is reached (Table 4.1).1–4 • The more mature a stallion is, the larger his epididymal sperm reserves will be.41 Age is an important factor to consider when determining the potential daily sperm output and the book of mares to a particular stallion. The average number of spermatozoa per ejaculate is about 50% higher during the breeding season than during the nonbreeding season. Declines in Leydig cell activity can occur in males beginning at 40 to 50 years of age. When the blood concentrations of testosterone once again decline, testosterone no longer interacts with the receptors to the same degree and GnRH and LH are once again secreted, stimulating more testosterone production. The end of the penis, called the glans penis, has a high concentration of nerve endings, resulting in very sensitive skin that influences the likelihood of ejaculation (see Figure 27.2). According to the Centers for Disease Control and Prevention (CDC), prostate cancer is the second most common cancer in males. As shown in Figure 27.2, the centrally located prostate gland sits anterior to the rectum at the base of the bladder surrounding the prostatic urethra (the portion of the urethra that runs within the prostate). A nutritional deficiencies (such as vitamins B, E, and A), anabolic steriod, metals (Cadmium and lead), X-ray exposure, dioxin, alcohol, drug toxicant and diseases of pathogens may also adversely affect the rate of spermatogenesis 29, 37. At 20°C (Man) -80°C (mouse) below body temperature, the optimum temperature is preserved. The spermatogenesis process is highly sensitive to environmental fluctuations, especially hormones and temperatures. There is a strong connection between morphological defects and the potential for sperm fertilization, since mature spermatozoa structures have the best organization to serve specific functions. Many diseases can make it more difficult to have an erection because of their impact on blood flow to your penis and other factors. In men/people AMAB with this birth defect, the urethra opens on the underside of the penis rather than at the tip of the penis. This is when your penis stays erect or partially erect for four hours or longer and is not caused by sexual arousal. Ejaculatory Duct In addition to its mucus-secreting cells, the inner mucosa contains ciliated cells that beat in the direction of the uterus, producing a current that will be critical to move the oocyte. The surge of LH also stimulates a change in the granulosa and theca cells that remain in the follicle after the oocyte has been ovulated. As noted earlier, the polar body that results from unequal cell division simply degrades. The outer genitals consist of a genital tubercle, paired labio scrotal swellings and paired urethra folds in the early embryo. One of the leading current concerns in medical genetics is the search for the main testis-determined gene. The current theory is that the development of an ovary or testis is determined by the synchronized action of a series of genes that contribute to the development of the ovary when there is no Y chromosome or there is no Y testicular development. The human reproductive system is made up of the primary and secondary organs, which helps to enhances reproduction. 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. During sexual intercourse, the sperm and egg can fuse to form a zygote, leading to embryonic development and the birth of a new human. Venous blood is drained from the penis by paired veins. Seminal vesicles Columns of erectile tissue called the corpora cavernosa and corpus spongiosum fill with blood when sexual arousal activates vasodilatation in the blood vessels of the penis. The fluid continues through the prostatic urethra, where secretions from the prostate are added to form semen. In men, LH binds to receptors on interstitial cells in the testes and up regulates the production of testosterone. FSH also stimulates the interstitial cells to produce hormones called inhibins, which function to inhibit FSH release from the pituitary, thus reducing testosterone secretion. In men, FSH binds predominantly to the sustentacular cells within the seminiferous tubules to promote spermatogenesis. The avian reproductive system is heterosexual and requires both a male and a female, each to contribute half of the genetic constitution of the offspring. The system includes the penis, scrotum, testicles, vas deferens, prostate gland, and seminal vesicles. The human body 9 male anatomy types illustrate the different variations in male reproductive and external genital anatomy. For proper reproductive function in the adult, one set of these ducts must develop properly, and the other must degrade. This is called the SRY (Sex-determining Region of the Y chromosome). To become a male, an individual must be exposed to the cascade of factors initiated by a single gene on the male Y chromosome. What are the functions of the female reproductive system? The cremaster relaxes when it is warm and the testicles are suspended further from the body. The cremaster contracts and pulls the testicles closer to the body when it is cold to keep them warm. The Leydig cell cytoplasm contains a lot of mitochondria, a granular endoplasmic reticulum, lipid droplets and occasionally some protein crystals . In this way, by inducing apoptosis of T lymphocytes, it avoids the immune attack of the developing sperm . Like the ovaries to which they are homologous, testes are components of both the reproductive system and the endocrine system.The ductus deferens is characterized by a thickened muscular coat of 3 layers (inner longitudinal, outer longitudinal, middle circular layer).Around three quarters of sexually active individuals have been exposed to HPV during their lifetime.From each epididymis, each vas deferens extends through the inguinal canal in the abdominal wall and continues to a region called the ampulla.Therefore, a defined number of sperm is available on a daily basis for ejaculation and once the daily sperm output is reached there is no benefit of collecting twice daily for artificial insemination programs.These small primordial follicles are present in newborn females and are the prevailing follicle type in the adult ovary.When semen is used for artificial insemination, storage under the right conditions can extend the life span of some species. These immature sperm are released into the lumen or hollow center of the seminiferous tubules and make their way to the epididymis. This location is important as viable sperm production in the testes requires a temperature 2 to 4°C below core body temperature. See Figure 16.1 for an illustration of the structures of the male reproductive system. (also, ductus deferens) duct that transports sperm from the epididymis through the spermatic cord and into the ejaculatory duct; also referred as the vas deferens It is stated that estrogen has a stimulatory and inhibitory effect on the proliferation and differentiation of germ cells. To initiate, sustain, and restore spermatogenesis, testosterone works synergistically with FSH. Sertoli cell products have been reported to play a role in the regulation of the functions of Leydig cells. Prostate Glands Symptoms such as vague perineal or penile pain, discomfort during ejaculation and haemospermia (blood in the ejaculate) are suggestive of such infection. The secretions of the seminal gland have a key role in the normal functioning of semen, making up 70% of its total volume. The seminal glands are a pair of 5cm long tubular glands. The centrally located prostate gland sits anterior to the rectum at the base of the bladder surrounding the prostatic urethra (the portion of the urethra that runs within the prostate). Because the ductus deferens is physically accessible within the scrotum, surgical sterilization to interrupt sperm delivery can be performed by cutting and sealing a small section of the ductus deferens. Human Anatomy and Physiology II Unit II These cells play a pivotal role in the production of testosterone, a key hormone that regulates various aspects of male reproductive physiology and secondary sexual characteristics. The key structures of the male reproductive system encompass the testes, epididymides, penis, and various ducts and glands involved in the production and conveyance of semen (Figure 3). For people with a penis, several accessory organs and ducts aid the process of sperm maturation and transport the sperm and other seminal components to the penis, which may deliver sperm to the female reproductive tract. Watch this video to explore the structures of the male reproductive system and the path of sperm, which starts in the testes and ends as the sperm leave the penis through the urethra. When the semen regains its fluid state, sperm can then pass farther into the female reproductive tract. Your pelvic bones support the weight of your upper body, together with the muscles of your pelvic floor.Beneath the penis lies the scrotum, a loose pouch of skin and muscle that houses the testes, or testicles.The cremaster muscle is a skeletal muscle that contracts to draw the scrotum closer to the body, thereby increasing warmth when temperatures drop.And most people, full-stop, will tend to want and need more than one part of their body touched in order to feel sexually satisfied.The brain receives and processes messages from your sensory organs, giving you and other parts of your body information about how something (or someone, including yourself) looks, sounds, tastes, smells and feels to you.Extending from the mesovarium itself is the suspensory ligament that contains the ovarian blood and lymph vessels.As you can see here, the ductus deferens comes up and over the bladder, and then it passes posteriorly and medially behind it.Consolidate your knowledge of the human reproductive system with a few more examples of our male and female reproductive system quizzes below. Spermatogonia and early spermatocytes live in the basal compartment and are readily available for systemic circulation. Tunica albuginea is subsequently thickened, assembling the testis mediastinum from which the fibrous septa penetrates the testis and divides into about 200 to 300 wedge-shaped lobules. Underneath the tunica vaginalis, Tunica albuginea is contained and forms the testis’ white fibrous capsule . There are normally two testis, each weighing about 11–17 g with the right one usually slightly larger and heavier than the left one weighing about 963 + 0 . Testes are located in the scrotum that regulates its temperature below the normal body temperature to approximately 23°C 1, 14. The seminal vesicles are a pair of glands that lie along the posterior border of the urinary bladder.The prostate is a walnut-sized gland that lies below the urinary bladder and surrounds the urethra.The impairment of spermatogenesis observed in AROM+ may be due to multiple factors, including cryptorchidism, abnormal Leydig cell function, testosterone deficiency or hyperestrogenemia (211).During ejaculation, muscles surrounding the seminal vesicles contract and push out the sperm and the fluid from the seminal vesicles, much like squeezing a tube of toothpaste.There are two epididymides and spermatic cords, two vas deferens and two ampullae, which empty into the pelvic urethra.While men remain fertile much longer than women, the male reproductive system does age.It combines fluids from the seminal vesicles, prostate, and bulbourethral glands, each contributing distinct components to create a unique and essential concoction for reproductive success. This duct is approximately 2.5 cm long and opens into the urethra at the base of the penis. The bulbourethral glands are compound tubulo-alveolar glands, each approximately the size of a pea. A healthy human prostate is slightly larger than a walnut in adult males, with a weight ranging between 7 and 16 grams. Some male hormones are produced in small amounts by the adrenal glands. The length of the epididymis delays the release of the sperm and allows them time to mature.Major functions of the cardiovascular system include transportation of oxygen, nutrients and hormones throughout the body within the blood, and as well as eliminating carbon dioxide and other metabolic waste.The spermatozoa mature progressively as they pass through the epididymis and are finally stored in the epididymal tail until ejaculation.It continues until it joins with the duct of the seminal vesicle to create the ejaculatory duct.Once decoagulated, the sperm can pass farther into the female reproductive tract.Once inside the female reproductive tract, sperm will move toward the unfertilized egg and will undergo chemical changes called capacitation in order to fertilize the egg. When we think of cerebrospinal fluid (CSF), we often imagine it simply as the protective liquid that cushions the brain… It is responsible for creating and delivering the genetic essence of life, sustained by a powerful hormonal framework and a coordinated network of organs and glands. These may include low sperm count, poor motility, structural abnormalities, or genetic disorders. For more in-depth evaluations, semen may be collected daily for 7–10 days in order to determine the daily sperm output. • Approximately 62% of the sperm available for ejaculation is stored in the tail of the epididymis. • Sperm located in the caput and corpus of the epididymis are not available for ejaculation until maturation and transit of the sperm are completed. Sperm stored in the ampulla, vas deferens and cauda epididymis can be released during ejaculation. So, you want to learn the anatomy of the reproductive system? These links are provided for your convenience only and do not imply endorsement by our business of the linked website or service. On the last day of the free trial, unless you have cancelled your subscription, you will be automatically charged the applicable subscription fees for the plan you have chosen. It is a separate organ that stores urine and empties it into the urethra for excretion. Although the bladder is located near the reproductive organs, it is not part of the reproductive system. The fertilized egg, called a zygote, will undergo many rounds of cell division while the cilia inside the fallopian tube push it along. Testosterone production by the body would be reduced if a male were taking anabolic steroids. While anabolic steroids (synthetic testosterone) bulk up muscles, they can also affect testosterone production in the testis. An erection is the result of this increased blood flow to the penis and reduced blood return from the penis. The mitotic division of spermatogonia results in two identical diploid cells. As mature gametes need to be haploid (n), containing 23 chromosomes, daughter cells of spermatogonia undergo a second cellular division through the process of meiosis. Subsequent transformations lead to the production of spermatids, which ultimately mature into functional sperm cells (Figure 6). This barrier is essential in averting an autoimmune response that might be triggered by the release of surface antigens, thus maintaining the integrity and immunological isolation of the developing sperm cells. Enveloping all stages of developing sperm cells are elongated and branching Sertoli cells, which function as supporting cells known as sustentacular cells or sustenocytes, typically found in epithelial tissue. The Big Picture: Purpose and Function of the Male Reproductive System Spermatogenesis is the male version of gametogenesis and results in the formation of spermatocytes possessing half the normal complement of genetic material. Spermatozoa are the mature male gametes in many sexually reproducing organisms. This energy is used for the journey through the female cervix, uterus, and uterine tubes. The head contains the nucleus with densely coiled chromatin fibers, surrounded anteriorly by an acrosome that contains enzymes for penetrating the female egg. Axoneme is the microtubule and related protein bundle that forms the center of the flagellum of eukaryotic sperm and is responsible for movement. A matured spermatozoon comprises of a tail and a head which contains a condensed nuclear material, a thin cytoplasm and a surrounding membranous layer . The above description categories spermatogenesis into major three divisions; spermatocytogenesis, meiosis and spermiogenesis respectively. In part 2, spermiogenesis occurs in which the spermatids are transformed in regards to metamorphic changes to sperm . This supports the importance of estrogens for the prenatal development and function of male reproductive structures, which is well documented in literature (87). In the male fetus both ERβ and aromatase are expressed in Sertoli, Leydig and germ cells from 13 to 24 weeks, whereas ERα expression is absent (86,87). Specifically, when fully developed spermatids are released from the epithelium, aromatase is present in the residual body (the remains of the spermatid cytoplasm that is removed during spermiation) and is subsequently phagocytosed by the Sertoli cell. Carreau et al. demonstrated that aromatase activity in germ cells was more than 50% of that of the whole testis (29). Aromatase mRNA expression and enzyme activity are present in both rat and mouse germ cells from the pachytene spermatocyte stage, and during their subsequent maturation into round spermatids (57,60,83) (Table 3). Within the scrotum, both glands are separated by the scrotal septum - a thin, vertically positioned midline fibrous tissue layer. The testicles are located in the scrotum, together with the epididymides (Read more!) and spermatic cords (Read more!). The testicles produce sperm and are the sites where spermatogenesis takes place. Where the sperm is stored; a tube that carries the sperm out of the scrotal sac. The tube that allows urine to pass outside the body. The prostate is an unpaired gland of the male reproductive system. The internal genital organs are the male gonads (testis), epididymis, a series of ducts and the accessory glands. The male gonads are the testes; they are the source of spermatozoa and also of male sex hormones called androgens. The reproductive system is responsible for human reproduction, with the primary sex organs being the testes in males and the ovaries in females. Each ductus deferens can easily be felt as it passesanterior to the pubic bone, looping medially over the ureter and descendingalong the posterior wall of the bladder. The ductusdeferentia, also called the vasadeferentia, are muscular tubesapproximately 45 cm (18 inches) inlength. Thesecretions of the seminal vesicles are discharged into the ejaculatory duct at emission. The surrounding fluid contains antimicrobial proteins suchas defensins. 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.The testicles make sperm and sex hormones, particularly testosterone.This chapter has addressed the reproductive effects of estrogens in males but there are emerging roles for estrogens in non-reproductive tissues.During sexual arousal, nitric oxide (NO) is released from nerve endings near blood vessels within the corpora cavernosa and corpus spongiosum.A long, muscular tube that transports sperm from the epididymis to the ejaculatory duct in preparation for ejaculation.The penis of the stallion is musculocavernous in nature.The process of spermatogenesis begins with mitosis of the diploid spermatogonia (Figure 15.1.4). When a mature follicle is examined an elongated area virtually free of blood vessels will be found on the distal surface of it. The ovary consists of a mass of yellowish, rounded objects called follicles, each containing an ovum or yolk. The ovary is well endowed with blood vessels to ensure there is no hindrance to the transport of nutrients to the developing yolk. Under a microscope the sperm of the fowl will be seen to have a long pointed head with a long tail. They are responsible for female growth and reproductive development. Internal male reproductive organs External male reproductive organs In the epididymis, the sperm takes about twelve days to mature and develop motility. The tail eventually joins with the vas deferens, providing an outlet for mature sperms to ejaculate. The epididymis is a coiled structure consisting of a head, body, and tail. In the interstitial tissue lie the Leydig cells that are responsible for testosterone production. The testes are the site of sperm production and hormone synthesis, while the epididymis has a role in the storage of sperm. It is possible for this fluid to pick up sperm remaining in the urethral bulb from previous ejaculations and carry them out prior to the next ejaculation. This fluid helps to lubricate the urethra for spermatozoa to pass through, neutralizes traces of acidic urine in the urethra, and helps flush out any residual urine or foreign matter. There is a 20% decrease in the efficiency of sperm production in mature stallions during the nonbreeding season.28 • Daily sperm production increases during the breeding season. It takes around 57 days for spermatogenesis to be completed from the stage of spermatogonia until a mature spermatozoon is formed. Notably, sperm counts, representing the total number of sperm a man produces, gradually decrease after the age of 35. The commencement of a new cycle takes place roughly every 16 days, although the synchronization of this timing varies among the seminiferous tubules. A complete spermatogenesis cycle, from spermatogonia to fully formed sperm, spans approximately 64 days. The entirety of this developmental cascade, commencing with spermatogonia and culminating in the generation of sperm, is collectively termed spermatogenesis. They contribute to the ongoing process of spermatogenesis by undergoing sequential divisions, resulting in the formation of primary and secondary spermatocytes. A passage in the lower anterior abdominal wall through which the spermatic cord passes in males (and the round ligament in females).During the last five years an increasing body of evidence suggest that estrogen may play a role on several other non-reproductive function in men.Testosterone causes the undeveloped tissues to differentiate into male sexual organs.Some penises are without them because they were removed, either for cultural reasons, because parents asked for a circumcision per what they understood as health reasons or because a parent made that decision based on their aesthetic preferences.Their function is concerned with reproduction and sexual pleasure.Douching (washing out the vagina with fluid) disrupts the normal balance of healthy microorganisms, and increases the risk for infections and irritation.The function of the male reproductive system (Figure 27.2) is to produce sperm and transfer them to the female reproductive tract.Whereas these vaccines were initially only targeted for women, because HPV is sexually transmitted, both men and women require vaccination for this approach to achieve its maximum efficacy.The epidermis is a thick keratinized epithelium made of multiple cell layers. Elevated cGMP levels cause smooth muscle cells within the walls of the penile arterioles to relax. Low blood concentrations of testosterone stimulate the hypothalamus to release GnRH, which, in turn, prompts the anterior pituitary to secrete LH. DHT is a more potent androgen and plays a crucial role in the development of male secondary sexual characteristics. In target tissues such as the prostate, skin, and hair follicles, a portion of testosterone is converted into dihydrotestosterone (DHT) through the action of the enzyme 5α-reductase. Once synthesized, testosterone circulates in the bloodstream and reaches various peripheral tissues. The testes are located within the scrotum, with the epididymis situated on the posterolateral aspect of each testicle. In this article, we shall look at the anatomy of the testes and epididymis – their structure, vasculature, innervation and clinical correlations. The testes and epididymis are paired structures, located within the scrotum. The penis is the male external organ used for both sexual reproduction and urination.The central nervous system definition is that it receives information from the body’s environment and generates instructions, thereby controlling all the activities of the human body.Spermatogenesis is the process by which male primary sperm cells undergo meiosis and produce a number of cells calls spermatogonia, from which the primary spermatocytes are derived.In the testosterone group, serum testosterone and estradiol varied from physiological levels to low levels according to the different doses of exogenous testosterone in each group and the estradiol to testosterone ratio remaining substantially unchanged in all groups (199).During meiosis, two cell divisions separate the paired chromosomes in the nucleus and then separate the chromatids that were made during an earlier stage of the cell’s life cycle.The accessory sex glands produce seminal fluid and clean and lubricate the urethra.In the epididymis, the sperm takes about twelve days to mature and develop motility.The epididymis is the tube from which the sperm is removed from the testicles. Ejaculatory fluid composed of sperm and secretions from the seminal vesicles, prostate, and bulbourethral glands. The temporary thickening of semen helps retain it within the female reproductive tract and once decoagulated the sperm can pass farther 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. Aggressive forms of prostate cancer, in contrast, involve metastasis to organs like the lungs and brain. However, some forms of prostate cancer grow very slowly and may not require treatment. According to the Centers for Disease Control and Prevention (CDC), prostate cancer is the second most common cancer occurring in men. Erectile dysfunction (ED) is a condition in which a male has difficulty either initiating or maintaining an erection. In females, the uterus and vaginal muscles contract in waves that may last slightly less than a second each. A low level of the hormone testosterone is released from male gonads in the developing embryos, starting at around the second month of gestation. It is lined cells that produce acidic secretions that limit the growth of microbes that could potentially travel into the uterus. Theprimary sex organs or gonads of themale consist of the two tes-tes, in which sperm cells and male sex hormones areformed. Spermcells are produced and maintained by the male reproduc-tive organs, which alsotransport these cells outside the body and secrete male sex hormones. Defects in androgen action, such as androgen insensitivity syndrome, result in a female phenotype despite male genotype due to an inability of the body's tissues to respond to testosterone. Other tests include semen analysis, which establishes fertility status and function of the seminiferous tubules, epididymis, and accessory sex glands. The semen then passes the bulbourethral glands or Cowper’s glands, which release a thick fluid that lubricates the urethral opening and clears the urethra of any urine residue. The lack of fluid reabsorption in the efferent ductules of αERKO male mice and the consequent dilatation induces a retroactive progressive swelling of the seminiferous tubules (27,52,60,69,111,126). Congenital estrogen deficiency in mice leads to an impairment of male reproductive function ranging from normal fertility with a fully male phenotype in βERKO mice, to complete infertility in both αERKO and αβERKO mice. The role of estrogens in the male reproductive system is clearer in rodents (see below), and the mapping of ERs and aromatase distribution in the human male reproductive system has led to the suggestion that estrogen plays a role in human male reproduction (4,53,55). Specifically, it is expressed in Leydig and Sertoli cells (101,102), in immature germ cells, from pachytene spermatocytes through elongated spermatids (57,101), and ejaculated sperm cells (103). Immunohistochemical analysis of testicular sections identified the GPR30 receptor in the cytoplasm of Leydig cells, Sertoli cells and spermatogonia (98). The testicle or testis is a paired oval-shaped internal genital organ of the male reproductive system. The testes are responsible for making sperm and are also involved in producing a hormone called testosterone. The prostate gland secretes a slightly alkaline fluid that forms part of the seminal fluid, a fluid that carries sperm. Most of the male reproductive system is located outside of the body. In target tissues such as the prostate, skin, and hair follicles, a portion of testosterone is converted into dihydrotestosterone (DHT) through the action of the enzyme 5α-reductase.This powerful hormone drives male sexual development, supports libido, maintains muscle mass and bone density, and regulates the production of sperm itself.Erection is brought about by distension of the cavernous spaces with blood, which is prevented from draining away by compression of the veins in the area.A severe impairment in tubule fluid absorption at efferent ducts level is the cause of infertility in αERKO male mice, and this defect is partially mimicked also by the administration of an anti-estrogen drug in wild-type mice (59,60,69).Unlike its male counterpart, the female reproductive system is located primarily inside the pelvic cavity.Without these stimuli, the Müllerian duct will develop and the Wolffian duct will degrade, resulting in a female embryo.Ejaculation is the ejection of semen from the penis and is usually accompanied by orgasm.These activities occur under the influence of hormones secreted by female sex organs (ovaries), as determined by the endocrine system. Accessory Organs Video Summary Each type shows variations in the size, shape, and positioning of the male reproductive organs front view, providing a fuller picture of male anatomy . These images offer a comprehensive front view of the male reproductive system, helping you see how each organ is positioned and how they function together. Looking at a picture of male reproductive system or male reproductive system real images can help you identify each organ and understand its function in reproduction. Visual tools like male reproductive system images and male reproductive anatomy pictures are incredibly helpful for understanding the detailed structure of the male reproductive system. If you're interested in learning about the site of storage and maturation of sperm, check out this article to understand where sperm are stored and matured in the male body. The spinal cord is a bundle of nervous tissue and other support cells. This fluorescent image shows nerve cells, from a rat brain, which were grown in the laboratory. When the bladder has filled up, it uses muscles to force the urine out of the body through the urethra. It is continuous with the skin of the lower abdomen and is located directly behind the penis and in front of the anus. This decline in progesterone results in the sloughing of the inner portion of the endometrium in a process called menses, or menstruation. The endometrium responds to estrogen released by the follicles during the menstrual cycle and grows thicker with an increase in blood vessels in preparation for pregnancy. The female reproductive organs are involved in sexual activity, fertility, menstruation and reproduction. Sertoli cells, which nurture and support developing spermatocytes, secrete a fluid into seminiferous tubules that helps transport sperm to the genital ducts. When erect, the stiffness of the organ allows it to penetrate into the vagina and deposit semen into the female reproductive tract (Figure 23.2.7). In warm weather, the muscle cells within the tunica dartos relax and allow the testicles to drop away from the body wall; in cold weather, the dartos muscle contracts, helping to pull the testicles closer to the body.• The scrotal fascia. Spermatozoa leave the tubules, move through the straight tubules and empty into the rete testis, then to the efferent ductules which in turn empty into the head of the epididymis. The horse’s immune system is never exposed to the developing spermatocytes or spermatids and would therefore see them as foreign cells and destroy them if it was not for the protection of the Sertoli cells. Lymphatic drainage of the proximal female urethra is to the internal iliac nodes, while the distal urethra drains to the superficial inguinal lymph nodes. The nerve supply to the female urethra arises from the vesical plexus and the pudendal nerve. They surround the vaginal vestibule and its urethral and vaginal orifices. The cleft between the labia majora is called the pudendal cleft. The uterine tubes are intraperitoneal organs, covered completely by a part of the broad ligament of the uterus called the mesosalpinx. Venous blood of the ovaries is drained by the pampiniform plexus.