How is sperm formed

Testosterone is responsible for normal male secondary sex characteristic development, libido or sex drive and normal erections. Testosterone is also important for sperm production, as levels of this hormone are 50 fold higher within the testis as in the blood.

Within the adult testicle, there is feet of tubing, termed seminiferous tubules, within which sperm is made. Sperm is made from precursor cells termed germ cells that give rise to approximately million sperm daily in a process termed spermatogenesis that takes approximately 64 days in humans.

This is equivalent to making about sperm per heartbeat. Within the seminiferous tubule, germ cells are arranged in a highly ordered sequence from outside to inside. Lining the tubules, there are adult testis stem cells that begin the process of sperm production. Overall there are 13 recognizable germ cell types in the human testis: dark type A spermatogonia Ad ; pale type A spermatogonia Ap ; type B spermatogonia B ; preleptotene R , leptotene L , zygotene z and pachytene primary spermatocytes p ; secondary spermatocytes II ; and Sa, Sb, Sc, Sd1, and Sd2 spermatids.

Despite the high volume production of sperm, quality control checkpoints exist throughout the sperm production process to ensure the biological and genetic integrity of ejaculated sperm. It has long been believed that sperm take 90 days 3 months to be made and ejaculated.

Turek recently discovered and published that in fact this time frame is actually much shorter. Sperm develop in the testicles for days and are then excreted into the coiled ducts of the epididymis and complete their maturation for another 14 days. Sperm waiting to be ejaculated remain in the epididymis, near the bottom of the scrotum. At ejaculation, sperm are propelled through the vas deferens within the spermatic cord and into the abdominal cavity and join the seminal vesicles, which add alkaline fluid that helps to support sperm.

The ejaculate consists of fluid from 3 sources: the vas deferens sperm fraction , the seminal vesicles, and the prostate. This mixture of semen then exits the penis during ejaculation.

The spermatozoon is a remarkably complex metabolic, locomotive and genetic machine. It is approximately 60 microns in length and is divided into 3 sections: head, neck and tail. The oval sperm head consists of a nucleus containing the highly compacted DNA, and an acrosome that contains the enzymes required for penetration of the egg shell for fertilization.

The inside of the penis is made of a spongy tissue that can expand and contract. All boys are born with a foreskin , a fold of skin at the end of the penis covering the glans.

Some boys are circumcised, which means that a doctor or clergy member cuts away the foreskin. Circumcision is usually done during a baby boy's first few days of life. It's not medically necessary, but parents who choose to have their sons circumcised often do so based on religious beliefs, concerns about hygiene, or cultural or social reasons.

Boys who have circumcised penises and those who don't are no different: All penises work and feel the same, regardless of whether the foreskin has been removed. 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. When puberty begins, usually between the ages of 9 and 15, the pituitary gland — located near the brain — secretes hormones that stimulate the testicles to produce testosterone.

The production of testosterone brings about many physical changes. Although the timing of these changes is different for every guy, the stages of puberty generally follow a set sequence:.

A male who has reached puberty will produce millions of sperm cells every day. Sperm develop in the testicles within a system of tiny tubes called the seminiferous tubules. At birth, these tubules contain simple round cells. During puberty, testosterone and other hormones cause these cells to transform into sperm cells.

The cells divide and change until they have a head and short tail, like tadpoles. The head contains genetic material genes. The sperm move into the epididymis, where they complete their development. The seminal vesicles and prostate gland make a whitish fluid called seminal fluid, which mixes with sperm to form semen when a male is sexually stimulated. The penis, which usually hangs limp, becomes hard when a male is sexually excited.

Tissues in the penis fill with blood and it becomes stiff and erect an erection. 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. The prostate gland, the seminal vesicles, and the bulbourethral glands contribute seminal fluid to semen, which carries and protects the sperm. During sexual intercourse, semen moves through a series of ducts to deliver the semen directly into the female reproductive system.

The testes or testicles are the male gonads and sit below the penis within a sac called the scrotum. They are cm long, 2. The testes generate sperm, the male sex cells, as well as testosterone and other sex hormones.

The production of sperm is constant and occurs within numerous lobules in each testis. First, structures called seminiferous tubules generate stem cells. These cells, the spermatogonia, divide into spermatocytes, and then divide further to become spermatids. The process is called spermatogenesis.

Spermatids move from the testis to the epididymis and mature into sperm. The epididymis, vas deferens, ejaculatory ducts, and urethra form a four-part transportation system. The epididymis sits directly on top of each testis. Sperm from the testis mature as they move through the coiled duct of the epididymis.

During sexual intercourse and ejaculation, they are expelled into the vas deferens. The vas deferens pushes the sperm up over the bladder and down toward the prostate gland. There, the vas deferens joins the ends of the seminal vesicles accessory reproductive glands to form the ejaculatory ducts.