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Thursday, July 4, 2019

The Male Reproductive System

     The Male Reproductive System





The Male Reproductive System





All living things reproduce. This is something that differentiates the living from the nonliving. Although the reproductive system is essential for keeping a species alive, it is not essential to keep a person alive. Reproduction can be known as the process by which an organism continues its species. Two types of sex cells (gametes) are involved in the human reproductive process: the male gamete (sperm) and the female gamete (egg or ovum). These two gametes are located within the female's uterine tubes (Female Reproductive System) located on both sides of the upper pelvic cavity and begin to create a new individual. The female needs a male to fertilize her egg; Then bring your offspring during pregnancy and birth



The Male Reproductive System

Organs Male Genitalia:


                                 (The development and transport of sperm)


Like other sexual animals, humans reproduce by mating. In humans, the reproductive tract includes both testicles, kept outside the abdomen by the scrotum, a series of channels and auxiliary glands and that of the penis. Not very active in childhood, the testes develop from puberty, which generally occurs between 12 and 15 years. Until the end of life, they produce male sex cells, called spermatozoa. The testes also play an endocrine role in the secretion of the main male sex hormone, testosterone



Anatomy of the male reproductive system:





The Male Reproductive System


External reproductive organs:


Penis and Scrotum:

The cylindrical bodies (two lateral cavernous bodies and a spongy central body) that make up the penis have the ability to gorge themselves under the effect of sexual arousal

The penis undergoes an important transformation called erection: it hardens, grows, lies down and gets up. Located in the center of the spongy body, the urethra transports sperm to the end of the penis, where it opens through the urethral meatus


Internal organs:


The testicles:


Wrapped in the layers of muscle and skin that make up the scrotum, the testicles are oval masses 3 to 5 cm long, divided into 250 lobes around. Each lobe contains small channels, called seminiferous tubules, within which male sex cells, sperm, develop. The tubules converge on the back of the testicles to form the testis network. When it leaves the testicle through the efferent ducts, the sperm reaches the epididymis. So the testes have two vital functions: making sperm and making testosterone (male hormone)

The location of the testicles outside the body cavity is essential for normal sperm formation, which occurs only at a temperature 1 to 4 ° C colder than body temperature. The scrotum is a skin pouch that wraps and contains the two testicles. It includes several muscle layers able to move the testicles away from the body and regulate their temperature. The ideal temperature for sperm development is 34 ° C. The interior is divided into several hundred lobes divided by partitions, each lobe containing:

 a. Seminiferous tubules: about 700 "of seminiferous tubules in the testes, the seminiferous tubules are covered with germinal epithelium, known as  spermatogonia. The seminiferous tubes are made up of many long, small and coiled tubes, in which the spermatozoa are produced and begin to mature (containing germ cells) and support the cells (Sertoli) - they protect the germ cells and promote their development

b. Interstitial cells: they are scattered between the seminiferous tubules, which produce testosterone:


  • Development and maintenance of secondary sexual characteristics
  • Stimulates protein synthesis
  • Promotes the growth of skeletal muscles


The epididymis:


The epididymis is a compact, flat, elongated structure, closely related to one side of the testicle. It is divided into three regions, the head, the body and the tail. The epididymis is tightly coiled, an 18 'tube that is located outside the testicles. Four main functions appear in the epididymis, including the transport of developing sperm from the testicle to the vas deferens: it takes about 20 days to pass the epididymis, when the sperm entering the epididymis are immature, immobile and unable to fertilize

The epididymis acts as an outlet for all the sperm produced in the testicle and for any blockage of this tube. will cause infertility. Temporary blockage due to swelling after injury or infection (epididymitis) will lead to short-term infertility. If inflammation or infection causes scar tissue to form in the tubule, it can permanently block the passage of sperm. If a blockage occurs in both epididymes, the bull will no longer be useful as a breeder


The vas deferent:


or vas deferens, a long muscular tube that runs from the eipdidymus into the scrotum, through the inguinal canal to the pelvic cavity and around the posterior side of the bladder, where it connects the ducts of the seminal vesicles. Sperm is transported along the reproductive tract into the pelvic region through the vas deferens by the contraction of the smooth muscle tissue that surrounds this tubule during ejaculation. Bulls can also be sterilized through a vasectomy in which a section of the vas deferens is removed so that sperm cannot pass into the urethra and out of the body


Ejaculatory Duct:


The seminal vesicle ducts join the vas deferens to form a short ejaculatory duct that crosses the prostate gland and joins the urethra


Urethra in the Penis:

The urethra is a single tube that communicates with two vas deferens. Anatomically, the urethra is the canal that passes through the penis. The urethra acts as a common conduit for the sperm of the reproductive tract and urine from the urinary tract, the ejaculatory duct connects to the urethra inside the prostate gland, the urethra opens through the penis


Accessory organs:

Three accessory glands secrete fluids that mix with sperm, and enter the urethra

• Seminal vesicles (paired): a pair of dorsal glands to the bladder, each about 5 cm long, is located in the region where the vas deferens join to become the urethra. The secretions of these glands make up most of the liquid part of the seed. Additionally, secretions activate sperm to become mobile. The seminal vesicles consist of two lobes about 10 cm long in the bull, each connected to the urethra by a conduit, the main function of which is the production of nutrients for the sperm: they secrete a viscous yellowish liquid rich in fructose (it serves as a source of energy for sperm), prostaglandins and other nutrients that represent about 60% of the seed

• Prostate gland (single) under the bladder, ~ 3 cm in diameter (golf ball size), the prostate gland is located in the neck of the urinary bladder, where it flows into the urethra. Around the ejaculatory duct at the intersection with the urethra it looks like a sponge; the walls have> 30 holes secrete a thin milky liquid containing citric acid, calcium and various enzymes and make up about 30% of sperm, this buffered solution (pH ~ 6.5) protects the sperm from the acidity of the male urethra and the Female vagina for 70 years, the majority (90%) of men show a certain degree of benign prostatic hyperplasia: it can compress the urethra, reduce the flow of urine, favor infections of the bladder and kidneys

• Bulbourethral glands (in pairs): small (~ 1 cm) pea-shaped glands under the prostate. During sexual arousal they produce a slippery and transparent liquid that lubricates the head of the penis in preparation for sexual intercourse, the clear and muffled discharge that often drips from the penis during sexual arousal before the service is largely produced by these glands and is used to rinse and clean the urethra from any residual urine that can be harmful to the sperm. It also protects the sperm by helping to neutralize the acidity of the residual urine in the urethra. protection against any low pH of the female reproductive tract and a decrease in pH due to sperm metabolism

Occasionally, one of the accessory glands can become infected, causing semen samples that are yellow and cloudy and contain pus cells. Sometimes antibiotic treatment is needed, but generally time will correct the problem




Physiology of the male reproductive system:


Reproductive Hormones:


The anterior pituitary gland acts as primary control of reproductive function, during puberty The pituitary ant secretes FSH and large quantities of LH (ICSH)

FSH and LH: they make the testes enlarge and start the production of spermatozoa

LH: activates interstitial cells to produce testosterone, the secretion of FSH and LH is fairly constant on a daily basis in men. The normal functions of male reproduction are largely controlled by hormones secreted by the endocrine glands. The testicle functions like an endocrine gland due to its production of the male hormone testosterone by interstitial cells (Leydig cells). The main functions of testosterone are:

• local effects on the development of sperm in the seminiferous tubules


• Stimulates the general protein synthesis

• Development and maintenance of secondary sexual characteristics associated with masculinity, such as the ridge and very muscular shoulders of a bull

• Promotes muscle development, bone growth, skin thickening and facial and body hair growth

• An important factor in man's normal sexual desire and behavior (~ sexual desire, aggression, courtship behavior)

The negative feedback circuit maintains a constant level of testosterone in the blood: high testosterone levels inhibit LH



Spermatogenesis:




The Male Reproductive System



Spermatogenesis describes the sperm development process in humans. It starts in the male testicle with the onset of puberty. It involves numerous steps that one by one lead to the development of a mature sperm, the spermatozoa are produced in seminiferous tubules (Sertoli cells): they produce a barrier of blood testes (it is formed just before puberty protects the sperm cells in development of certain proteins, hormones, ions and drugs that can damage the sperm also prevents the spread of sperm in the blood), nourishing the developing sperm (secrete a fluid rich in proteins, enzymes and testosterone in the seminiferous tubules), also engulfing any damaged sperm and develop from a sperm type of stem cell

Spermatogenesis is highly dependent on adequate testosterone levels and can be influenced by hormonal fluctuations in the body



Structure of a Sperm 



The Male Reproductive System



Composed of a head, a central piece and a tail :


  • Head: long "pear-shaped" (tip = acrosome), thin lysosome that covers the head, contains enzymes that will be used to penetrate the egg and enzyme inhibitors
  • Midpiece: cylinder containing numerous mitochondria: produces the ATP necessary for propulsion
  • Tail: bundle of single cell filaments (flagellum) in the body with means of locomotion of the flagellum

The  path  of  spermatozoids :

Regularly produced by the testes, spermatozoa are stored in the epididymis, where they continue to mature. Sexual arousal causes them to increase in the vas deferens. They mix with the secretions of the seminal vesicles, the prostate and the Cowper glands to form a whitish liquid, the sperm. If the stimulation is intensified, the spermatozoa are expelled from the urethra by the rhythmic contractions of the muscles at the base of the penis: it is ejaculation


How many spermatozoa are ejaculated?



  • Since puberty, testicular stem cells produce between 10 and 30 billion spermatozoa per month and 30 billion spermatozoa per month
  • These move through the seminiferous tubules to the epididymis
  • Sperm production takes a few months and the epididymis mature in a few days
  • Typically 40,000,000 sperm per ml in 5 ml 6 of 35 Typically 40,000,000 sperm per ml in 5 ml of ejaculation, or 200,000.00 spermatozoa released in a single ejaculation


Disorders of the male reproductive system:


• Hypogonadism is present in 0.13% of men due to a pituitary malfunction

• Hypergonadism leads to excessive development of the genitals and secondary sexual characteristics

• Prostatitis: An inflammation of the prostate

• Prostate cancer is the second most common cancer in men (after lung cancer) and affects around 9% of men over the age of 50

• Erectile dysfunction About 20% of men in the 60s and 50% in the 80s suffer from erectile dysfunction (= impotence)

• Pollutants have been implicated in dramatic effects especially on the male reproductive system, these pollutants are imitations of estrogens called endocrine disruptors


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