Male Anatomy and Physiology
For majority of the population, talking about the male reproductive system is a major issue. Such region of the body is considered as private thing that many believe should not be discussed in public. However, it is important to note that proper knowledge about the male anatomy and physiology is a process that contributes to scientific discovery of the causes and treatments of infertility among males.
During the prenatal period, the genital part of a child is not fully identified. This is because the genital tissue of a boy or a girl is the same as it is formed from the same fetal tissue. At the eighth week, the gonad of the fetus presents no difference. These gonads become the ovaries or testes. However, the development of the male reproductive system would only be possible if there is an extreme influence of the Y chromosome. Once the Wolfian ducts mature because of the testosterone production, it would eventually become the genital duct system of the male which is comprised of the epididymis, seminal vesicles and the vas. During the same period, the production of Mullerian Inhibiting substance (MIS) by the testicles causes the Mullerian ducts to degenerate. These degenerated Mullerian ducts would later develop into the fallopian tubes and the uterus among females. The external genital system among males which is comprised of the scrotum and the penis develops once the testosterone is converted into dihydrotestosterone through the aid of an enzyme known as enzyme five alpha reductase (Harvard-MIT Division of Health Sciences and Technology, 2002)
Male External Genital System
The external genital of males is made up of the scrotum and the penis. The scrotum is identified as a pouch-like skin located behind the penis which carries the testes or testicles. Inside this bag of skin, the testes are suspended through the help of the spermatic cord which is comprised of nerves and blood vessels. Likewise, the scrotum contains fibers known as cremasteric muscles which draw the testicles close to the body. The scrotum is also responsible for regulating the temperature needed by the testicles for the sperm production. During warm weather, the pouch hangs loosely away from the body and becomes larger in order to reduce the extra heat. Whenever the body is cold, the scrotum shrinks and becomes tighter in order to hold the body heat needed by the testicles. In addition, the scrotum’s outer layer is darker in color compared to the other tissues in the body while the inner part of the scrotum is made up of tunica dartos which are smooth fibers of muscles responsible for drawing the pouch closer to the body whenever the testes is exposed to cold. During adolescence, the scrotum is covered with substantial amount of hair. On the other hand, the penis is the organ responsible for passing sperm and urine. This part extends to the pelvic cavity and is attached to the bone in the pubic area. Majority of the part of the penis does not have muscles and bones except for the area located at the tip of the penis which has muscles needed for ejecting sperms and urine (Schnelker, 2002).
Male Internal Genital System
Inside the Penis
Basically, the penis is made up of two parts: The glans which is also known as the head, and the shaft which is the main part of the penis. The rim portion of the glans is known as the corona which is packed with nerve endings. Inside the penis lies the urethra—a thin lining where the urine passes. The urethra is also used for expelling the semen. Accordingly, the penis is comprised of various structures, the smallest of which is the spongy body or corpus spongiosum which stretches, forming the glans. The two larger structures are known as the cavernous bodies or the corpora cavernosas which are positioned side by side and are connected to the pubic bone’s innermost tip known as the crura. Both the cavernous bodies and the spongy body are responsible for the erection during sexual excitement or arousal and sleep. This is so because the structures are then filled with more blood from the arteries than the veins could actually carry away, causing engorgement (Schnelker, 2002).
Inside the Scrotum
It was stated earlier that the scrotum carries the testes or testicle. There are two testicles in the male reproductive system. Testes are oval in shape and their length grows about two inches and one inch in diameter. According to research, the testicles have three major functions. Among adults, the testes serve as an exocrine gland responsible for producing and storing the sperm cells. The testes are also considered as a part of the endocrine system because they produce hormones which include the testosterones. The additional function of the testicles is essential during the process of prenatal development of the genitals of the fetus wherein the secretion of the Mullerian Inhibiting substance (MIS) results in the development of the female structure (Harvard-MIT Division of Health Sciences and Technology, 2002).
Inside the Testicles
The testicles are primarily made up of seminiferous tubules and the interstitial cells. Each testis contains approximately 500 tubules which range from 30 to 70 cm in length and about 200 to 300 microns in diameter. The seminiferous tubules are closely packed together and are made up of germ cells which morphologically mature into spermatozoa and sertoli cells which function as supporting cells for the development of the germ cells (Sheynkin, 2000). Sertoli cells, which are tall and columnar in form, create a blood-testis barrier, separating the germinal epithelium into two compartments which are the basal and the adluminal. Immature germ cells are then placed into the basal compartment while progressive or mature germ cells are situated at the adluminal compartment which is said to be a “specialized micro-environment” (Harvard-MIT Division of Health Sciences and Technology, 2002).
On the other hand, the interstitial cells, which are located between the seminiferous tubules, contain the Leydig cells that are primarily responsible for the production of testosterone, a hormone that serves various purposes. Testosterone causes changes in the body, such as the masculinization of the reproductive tissues, deepening of voice during the stage of puberty, development of facial hair, and changes in libido and sexual behavior. In addition to this, testosterone also stimulates and supports the sertoli cells in order to function properly in providing the right environment for the maturing germ cells (Harvard-MIT Division of Health Sciences and Technology, 2002).
The Duct System
The duct system is composed of the epididymis and the vas deferens. Epididymis is a single complex duct that is divided into three sections: the caput or head, the corpus or the body, and the cauda or the tail. This structure which is three to four meters in length serves various functions: (1) sperm passage—the epididymal passage of the sperm is launched by the contraction in the duct which last for about 12 days; (2) fluid resorption, wherein a large amount of fluid entering the caput is absorbed again during the epididymal passage; (3) sperm storage; and (4) sperm maturation, where the fertilizing capacity of the sperm takes place. The vas deferens, on the other hand, is a single duct tube which travels upward towards the spermatic cord and extends into the urethra (Harvard-MIT Division of Health Sciences and Technology, 2002). The vas deferens is 35 to 45 cm in length which contains muscular layers. The anatomical locations of the vas deferens is said to be divided into three portions: the scrotal, inguinal, and reproperitoneal. Vas deferens is also dependent in the substance known as the androgen and is responsible for transporting the semen, a sperm containing fluid, into the pelvis where it is then joined by the seminal vesicles forming the ejaculatory duct. The ejaculatory ducts are large tubes entering the prostatic urethra. Prior to ejaculation, the testes are moved closer to the male’s abdomen. As such, the fluid is rapidly transported through the vas deferens and passes to the ejaculatory duct and then towards the prostatic urethra (Sheynkin, 2000).
The accessory glands of the male reproductive system are comprised of the seminal vesicles and the prostrate gland. Both are responsible for providing the necessary fluids that lubricate the duct system and sustain the sperms (Dowshen, 2007). Seminal vesicles are two small glands that contain most of the fluid of the semen. The said fluids are filled with alkaline and fructose which helps in the nourishment of the sperm so that the cells can swim with their tails. The prostate gland, which is located at the bottom part of the bladder, produces small amount of seminal fluid. The small amount of alkaline secretion goes directly to the urethra and eventually joins the semen and seminal fluid prior to ejaculation (Schnelker, 2002).
Ultimately, the function of the male reproductive system is to produce and release the semen inside the reproductive system of the female during sexual activity. Once the male has ejaculated, the semen is then deposited to the female’s genitals, and from there, the sperm would travel towards the cervix moving to the uterus through the help of uterine contractions. The presence of mature egg in the fallopian tube of the female could be penetrated by the sperm which would eventually lead to the fertilization or conception. Subsequent activity inside the female’s reproductive system would then result in pregnancy (Dowshen, 2007).
Based from the facts stated in the study, the male reproductive system is a complex structure that would require appreciation in order to understand how it functions. By understanding the anatomy and physiology of male, various advancements in scientific research can be empowered in order to give solutions to problems that concern the disorders that arise among males. Furthermore, it is suggested that further investigation should be done in order to give light to some of the issues that were not covered in this paper.
Dowshen, S. (2007, November). Male reproductive system. Kids Health. Retrieved
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Center. Retrieved September 26, 2008 http://daphne.palomar.edu/psycsoc125/HSClass/anatomy_ts/pages/m_anat.html
Sheynkin, Y. R. (2000). Brief anatomy and physiology of the male reproductive system.
Spermatogenesis. Fertilization. Stony Brook University Hospital. Retrieved September
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