Diagram of the male reproductive system

The male reproductive system is mostly outside the human body and can be seen directly. Because their sex organs are more prominent and easily accessible, men are stimulating their sex organs to get some kind of pleasure at an earlier age than women. Because men urinate through their genitals, they must easily get their genitals out of their pants, so men are subject to far fewer social restrictions than women in terms of touching their genitals (except in some places where men are prohibited from touching their genitals, but they are not likely to be restricted at all times).

In addition, men see their penis every day, and they may pay less attention to other reproductive organs, and like women, they know nothing about the functions of internal genitalia. In the letters we receive, most of the questions asked by men are about the penis, the appearance of male testicles, erection, male ejaculation and male prostate.

Male reproductive organs

A major difference between the male and female reproductive areas is that men have two openings, one at the top of the penis where urine and semen are discharged, and the other at the anus behind the scrotum; while women have three openings: the urethra, the vagina, and the anus.

Among the male reproductive organs, the most prominent is the male genitalia, which includes the shaft of the penis and the glans penis.

Inside the male genital shaft is the urethra (through which urine and semen are discharged from the body), which has three layers of cylindrical tissue. The outer skin covers the outside of the male genital shaft and can be moved to make it hard.

The cylindrical tissue located under the penis axis is the corpus cavernosum. When the penis is erect, the bulge of the corpus cavernosum looks like a valley. The urethral opening is located in the center of the corpus cavernosum. The other two cylindrical tissue bodies are the corpus cavernosum, located above the penis wheel.

The three-layered dendritic tissue is filled with many small blood vessels and sponge-like tissue. When filled with blood, it will swell, and this swelling will cause the penis to become larger and longer, which is the state of erection. Each cylindrical tissue is tightly surrounded by a thin film, and when the blood swells, the male genitals become harder and harder during erection.

The head of the penis is also called the glans penis (gfans), which also has spongy tissue. The urethra is located in the glans penis. The coronary artery is located between the penis shaft and the glans penis. The glans penis, the coronary artery and the frenulum penis are filled with peripheral nerves. They are very sensitive to stimulation.

The genital suture (ranhe) is located on the center line of the epidermis under the genital axis. It is produced before birth. For men who have not undergone circumcision, the epidermis basically surrounds the entire genital axis, but does not extend over the glans. The epidermis that can be retracted is called foreskin.

Although it cannot be seen from the outside, the structure of the penis is connected to the inside of the human body, and the urethra is connected to the pancreas (bladder) through the center of the prostate, and the corpus cavernosum of the penis also widens to the pelvic area, connecting with blood vessels, pelvic muscles, and bones.

The glans penis and upper genital shaft of men and the clitoris of women are the same tissues in vitro. Therefore, when men and women are sexually excited, they will swell due to filling with blood, and after multiple climaxes, they will become unable to stimulate sexually.

Many men think that their penis is smaller than it should be. Since this is a key issue for men, they expect biologists to do a lot of scientific research on the size of the penis. In fact, there are not many scientific studies on this aspect, and the accuracy of the results still needs to be weighed, because there are only a few such scientific studies. Some people measure the size of their penis accurately at home and then report it to the researchers, not the exact size measured by the researchers; some people measure the size of their penis after erection, not the normal size. Therefore, we should also adopt a conservative attitude towards the following survey report.

The normal (non-erect) size of a penis is about four inches, but some men may have a longer or shorter penis. Many factors may affect the normal size of a penis, including excess body fat, low temperatures, and stressful situations. According to a survey report by Masters and Johnson, men with shorter penises were found to have a higher percentage of penis enlargement when erect than men with longer penises. Therefore, according to current data, the size of most men's penises when erect is about five to seven inches long. Of course, there are also many men whose penises may be longer or shorter when erect.

Behind the genitals is the scrotum, a bag made of loose skin and superficial fascia. When exposed to cold, exercise or sexual excitement, the muscles of the scrotum will contract to pull the testicles in the scrotum closer to the body. This makes the testicles closer to the body or prevents movement, which is very important for the testicles. Because the testicles must be kept at a temperature slightly lower than the body temperature, exposure to cold or heat will cause sperm to decrease. If exposed to cold environments for a long time, it may cause infertility and increase the risk of testicular cancer. Undescended testicles refer to the situation where the male testicles do not descend into the scrotum when the baby is born, but remain in the pelvis. This condition can lead to infertility.

The male testicles are twin oval glands, about five inches long and one inch wide, with one testicle usually lower than the other. There are Leydis cells in the male testicles, which metabolize testosterone, which is essential for male development, male sexual function, and secondary sexual characteristics. In addition, there are seminiferous tubules in the male testicles, and the Sertoli cells in the seminiferous tubules can continuously produce sperm from puberty to death.

The male testicles are connected to the human body through the spermatic curve. There are blood vessels in the spermatic curve that allow testosterone to enter the blood, and there are also ejaculatory ducts (vas deferens) that allow male sperm to enter the urethra from the male testicles.

The anus is located behind the scrotum.