The long migration route and what shape is healthy?

**A Long Migration Journey**

We are testicular babies, two brothers still in swaddling clothes, but Mom is heartless enough to kick us out of the house. Mom said, "It's not that I'm heartless, it's because our hometown is a tropical region, the temperature is too high, which is very unsuitable for your growth and development. Here you will never grow up and become useless."

Our birthplace is the retroperitoneal space. It's like a large valley, with the abdominal cavity in front, where many internal organs work busily every day, radiating heat waves that raise the temperature to 38°C. Behind us is the lower back, like a thick wall, blocking the heat. Living in this valley, we were unbearably hot and humid every day; the high temperature was very detrimental to our growth and development. That's why Mom had to send us out of the house so early.

Before we set off, Mom carefully told us the migration route: we had to walk down the rugged mountain path, cross some hills, and pass through a long tunnel (the inguinal canal) to reach our destination-the scrotum.

We tearfully said goodbye to our mother, picked up our food and luggage, and were about to set off. But our mother was still very worried. She repeatedly told us, "Don't play around on the road. Remember the route and don't get lost! The journey is long and arduous, so take care of yourself and be careful. You must reach Yin Nang within a year."

We slid down the ravine, and as we glided down the broad back, it seemed like we crossed it effortlessly. After resting for a few days, we slowly climbed over the hills (iliac vessels) of all sizes, lying down to rest for a day or two when we got tired. Every day, we had to eat and drink our fill before we could move; the "nutrients" our bodies provided were androgens. Mom said that some testicles, lacking "nutrients" during their migration, would collapse from hunger. If, under a doctor's guidance, we could use human chorionic gonadotropin (hCG) to stimulate the body to secrete more androgens, ensuring a sufficient supply of nutrients for the testicles, perhaps this situation could be changed. We were quite lucky; our nutrient supply was plentiful, and our journey went smoothly. Looking at the calendar, only three months had passed, and we had already completed half the journey. Mom had given us a year, which was still plenty of time.

Next, we had to traverse a long, narrow tunnel. The tunnel entrance (the inner ring) was small and well-hidden, and many testicles took the wrong path here, losing their way and heading towards the abdominal wall, groin, and other areas, where they had nowhere to go and were forced to stop. Medically, these testicles are called ectopic testes. We must not make this mistake. After careful re-identification, we accurately entered the "tunnel." This tunnel was full of "thorns," and if you weren't careful, you would get entangled and unable to escape. Many testicles were just about to reach their destination when they were entangled in the thorns and made their home there. Doctors call those testicles that stopped along the way cryptorchidism.

After a long journey of more than six months, we finally arrived at the scrotum. Upon entering, we discovered that the climate here is spring-like all year round. When the temperature is high, the scrotum expands, making the scrotal cavity more spacious for ventilation and heat dissipation, quickly lowering the temperature; when the temperature is low, the scrotum contracts, thickening the scrotal walls to retain warmth. This allows the testicles to live comfortably and grow healthily in this constant temperature environment.

Those undescended testes that remain in different locations or along the way, such as the retroperitoneum or inguinal canal, often suffer from impaired physical development due to excessively high temperatures, remaining immature for several years. Therefore, if their growth and development period is missed, changing their environment will be futile. In a small number of cases, prolonged exposure to high temperatures can even lead to cell mutations and endanger human life.

If undescended testicles have remained in an undescended location for more than a year, they cannot descend back into the scrotum on their own. Therefore, it is necessary to consult a doctor as soon as possible to assist these undescended testicles. Ideally, the undescended testicle should be moved into the scrotum before the age of 6, otherwise, the development of the undescended testicles will be severely affected.

Author: Zhong Wei, Chief Physician of Urology, Beijing Coal General Hospital

What shape is healthy?

A patient came to the clinic for a consultation: My penis always bends to the right when erect, but I can still have sex. Is this erectile dysfunction normal?

This patient's question is one that many men are concerned about. Because the penis is often a symbol of masculinity, both men and women desire it to be magnificent, erect, and vigorous, reflecting male strength.

Normally, the penis is flaccid. When sexually stimulated, the amount of blood filling the corpora cavernosa causes the penis to stand erect, much like the mast of a sailboat. Due to differences in the distribution and degree of blood filling within the corpora cavernosa, the erect penis can present various angles, with the most common being 70°–120°. Sometimes, due to the sensitivity of the nerve endings in the glans penis, the penis may be very hard while the glans is relatively soft, or the penis may bend laterally or ventrally. However, if this does not affect sexual intercourse, slight curvature during erection is normal.

However, some types of priapism should raise concerns. Some men experience priapism that can last for hours, days, or even months, even without sexual desire. This can occur due to occlusion of small arteries in the penis and obstruction of venous return, causing pain. If this pathological condition recurs over a long period, it will inevitably lead to fibrosis of the corpora cavernosa, ultimately resulting in loss of erectile function. In addition, there is Peyronie's disease, which is more common in middle-aged and older men (40-60 years old), and can also hinder erection, causing erectile pain. In this case, the penis is generally asymptomatic in the flaccid state, but one or more fibrous nodules are prone to form in the loose connective tissue between the corpora cavernosa and the tunica albuginea, causing dorsiflexion or lateral curvature of the penis during erection, which can severely affect normal sexual intercourse. Furthermore, conditions such as epispadias, hypospadias, and a short frenulum can all cause penile curvature; significant lateral curvature or ventral curvature of the penis can affect sexual intercourse. These symptoms should be addressed promptly by seeking medical attention.

In clinical practice, there are some unusual penile erection patterns. For example, dipyrion is a rare male external genital abnormality, estimated to occur in only 1 in 5.5 million births. In a typical case of dipyrion, only one penis is erect, and it often points upwards during erection. Additionally, there is a type called concealed penis: the penis is extremely small and underdeveloped, with thick subcutaneous fat surrounding it, making it virtually invisible. Painful erections may occur, but intercourse is impossible. These should also raise suspicion.

Author: Wang Qi, Professor, Beijing University of Chinese Medicine