The rigidity of the erect penis makes it easier to insert into the female's vagina during sex. When the erect penis is stimulated, muscles around the reproductive organs contract and force the semen through the duct system and urethra. Semen is pushed out of the male's body through his urethra — this process is called ejaculation.
Each time a guy ejaculates, it can contain up to million sperm. If semen is ejaculated into a female's vagina, millions of sperm "swim" up from the vagina through the cervix and uterus to meet the egg in the fallopian tube. It takes only one sperm to fertilize the egg. This fertilized egg is now called a zygote and contains 46 chromosomes — half from the egg and half from the sperm.
Genetic material from the male and female combine so that a new individual can be created. The zygote divides again and again as it grows in the female's uterus, maturing over the course of the pregnancy into an embryo, a fetus, and finally a newborn baby.
Reviewed by: Larissa Hirsch, MD. Larger text size Large text size Regular text size. What Is Reproduction? What Is the Male Reproductive System? The male genitals include: the testicles TESS-tih-kulz the duct system, which is made up of the epididymis and the vas deferens the accessory glands, which include the seminal vesicles and prostate gland the penis In a guy who has reached sexual maturity , the two oval-shaped testicles , or testes TESS-teez make and store millions of tiny sperm cells.
The male reproductive system: makes semen SEE-mun releases semen into the reproductive system of the female during sexual intercourse produces sex hormones, which help a boy develop into a sexually mature man during puberty When a baby boy is born, he has all the parts of his reproductive system in place, but it isn't until puberty that he is able to reproduce.
Although the timing of these changes is different for every guy, the stages of puberty generally follow a set sequence: During the first stage of male puberty, the scrotum and testes grow larger. Next, the penis becomes longer and the seminal vesicles and prostate gland grow.
Hair begins to grow in the pubic area and later on the face and underarms. The testes also produce a hormone called testosterone. This hormone is responsible for sex drive, fertility, and the development of muscle and bone mass.
The main function of the testes is producing and storing sperm. Testes get their ovular shape from tissues known as lobules. Lobules are made up of coiled tubes surrounded by dense connective tissues. Seminiferous tubules are coiled tubes that make up most of each testis.
The cells and tissues in the tubules are responsible for spermatogenesis, which is the process of creating sperm. These tubules are lined with a layer of tissue called the epithelium. This layer is made up of Sertoli cells that aid in the production of hormones that generate sperm. Among the Sertoli cells are spermatogenic cells that divide and become spermatozoa, or sperm cells.
The tissues next to the tubules are called Leydig cells. These cells produce male hormones, such as testosterone and other androgens.
After sperm is created in the seminiferous tubules, sperm cells travel toward the epididymis through the rete testis. The rete testis helps to mix sperm cells around in the fluid secreted by Sertoli cells. The body reabsorbs this fluid as sperm cells travel from the seminiferous tubules to the epididymis.
Millions of tiny projections in the rete testis, known as microvilli, help move sperm along to the efferent tubules. The efferent ducts are a series of tubes that join the rete testis to the epididymis. These ducts are lined with hair-like projections called cilia. Along with a layer of smooth muscle, cilia help move the sperm into the epididymis. The efferent ducts also absorb most of the fluid that helps to move sperm cells.
This results in a higher concentration of sperm in ejaculate fluid. Tunica vasculosa is the first thin layer of blood vessels. This layer shields the tubular interior of each testicle from further layers of tissue around the outer testicle. The next layer is called the tunica albuginea. The outermost layers of tissue are called the tunica vaginalis. The tunica vaginalis consists of three layers:. A hydrocele happens when excess fluid builds up in the cavities around one of your testicles.
This is sometimes present at birth, but it can also result from an injury or inflammation. Most go away on their own, but more severe cases might require surgical removal. Testicular torsion means that your testicle has rotated in the scrotum. This can wind up the spermatic cord, cutting off blood supply, nerve function, and sperm transport to your scrotum. Seminiferous tubules house germ cells — the 23 chromosome cells that men replicate to produce sperm — and they are the site of sperm production, or spermatogenesis, according to VMC.
These tubules are tightly coiled within the testis, and each testis may contain up to tubules. The tubules are almost 20 inches 50 cm long, and a typical testis contains up to half a mile meters of seminiferous tubules. A fibrous tissue called the tunica covers the tubules. The tunica has three layers: the tunica vasculosa, the inner layer that consists of blood vessels and connective tissue; the tunica albuginea, which encases the testes and connects to the fibers that surround the epididymis, which transports sperm out of the testes and into the penis; and the tunica vaginalis, which contains fluid that reduces friction between the testes and the scrotum.
Besides sperm, testicles also produce male hormones called androgens. Androgens control how the male reproductive system grows, and the development of "masculine" body features such as beards and a deep voice. They also influence sexual functions. Testosterone is the most common form of androgen. It is responsible for the growth of male genitals and sperm production. Testicles in a healthy male can produce about 6 milligrams of testosterone each day, according to VMC.
Testosterone is important in the first stages of developing the male reproductive organs in a foetus. It also causes the development of male characteristics such as growth of facial hair, deepening of the voice and the growth spurt that takes place during puberty. From puberty onwards, testosterone provides the main stimulus for sperm production. Many things can wrong with the testes; they can be grouped into physical injury and diseases or conditions that affect the function of the testes:.
Other factors that can affect the function of the testes are radiation and chemotherapy used in the treatment of cancer , certain drugs, and disorders of the pituitary gland that stop signals from the hormone endocrine system that trigger production of testosterone from the testes.
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