The source of male virility in the testes and the process of sperm production and maturation
The scrotum is composed of multiple layers of tissue, from the outside in: skin, dartos fascia, and the tunica vaginalis covering the testis and spermatic cord. This tunica vaginalis can be further divided into the cremasteric fascia, cremaster muscle, tunica vaginalis of the spermatic cord, tunica vaginalis proper of the testis, and the tunica vaginalis cavity. The subcutaneous tissue of the scrotum is the dartos fascia, 1-2 mm thick, mainly composed of smooth muscle, containing dense connective tissue and elastic fibers. The scrotal skin has the ability to form small folds due to the contraction of this muscle. Beneath the dartos fascia is a layer of striated muscle and connective tissue (cremasteric fascia), which is a continuation of the internal oblique muscle extending into the scrotum. This membrane forms the sheath surrounding the spermatic cord. In cases of extreme scrotal enlargement, two additional layers can be distinguished: the external spermatic cord fascia, the aponeurotic sac of the external oblique muscle; and the internal spermatic cord fascia, the aponeurotic sac of the transversus abdominis muscle. The inner surface of the scrotum is covered by the parietal layer of the tunica vaginalis. The mesothelial cells that make up the tunica vaginalis and the macrophages located within it both have phagocytic activity.
**The testicles play a crucial role in restoring male virility.**
In many parts of Japan, on certain major festival days, women go to shrines to burn incense and worship male phallus-shaped objects. On the day of the festival, people often carry out the main deity statue-a wooden penis about 7 meters long and 1 meter in diameter-in a palanquin, and everyone worships and cheers before it, praying for abundant harvests and numerous offspring. Within the shrine is an inner hall called the "Okumiya," which enshrines various gods. To express gratitude for the gods' blessings, people specially craft various genitalia, such as penises and testicles, from wood; they are remarkably lifelike.
In ancient China, to prevent male servants from having sexual relations with their concubines and to ensure the purity of their bloodline, emperors decreed that eunuchs must have their testicles removed before entering the palace. Similarly, in ancient Europe, Christian communities would remove the testicles of male choir members to prevent their voices from changing as they grew up.
The testicles are the most important sex organs for men. They produce sperm and secrete androgens, and are fundamental to what makes a man a man. Every man has a pair of testicles, and even if one testicle is lost due to an accident, a man's male characteristics can still be retained.
The testicles are the site of male hormone production; therefore, eunuchs would lose certain male characteristics, such as not growing facial hair or body hair, and having an erectionless penis. The testicles are the source of male virility. This is not merely a popular folk belief, nor simply a prominent marker of male sexual characteristics, but rather a reflection of their consistent and tangible fulfillment of this sacred duty. The testicles are a pair of oval-shaped, solid organs, smooth and light pink in color. The left testicle is slightly larger, weighing about 20 grams. Newborns have relatively large testicles, which increase slowly from birth to pre-puberty, rapidly increasing in size during puberty, reaching their maximum size around age 25, and gradually shrinking in old age. Due to the scrotum and its unique blood supply system, its temperature is 2-3°C lower than body temperature.
The testes have two main functions: producing sperm to maintain reproduction and producing androgens to maintain male sexual characteristics and fertility. These two functions are generated and completed within the seminiferous tubules and testicular interstitium. The seminiferous tubules are 30–80 cm long and approximately 200 μm in diameter. They contain spermatogenic cells, which gradually produce sperm from spermatogonia, primary spermatocytes, secondary spermatocytes, and spermatids. A single spermatogonia can divide multiple times to form 256 spermatids, half of which contain a Y chromosome and half contain an X chromosome. Sperm maturation takes approximately 64 to 72 days. The seminiferous tubules also contain Sertoli cells, which form the blood-testis barrier, provide endocrine support, release and nourish sperm, and engulf sperm. The testicular interstitium, located between the seminiferous tubules, primarily secretes androgens, while also secreting small amounts of estrogen. Androgens are the most important and fundamental factors that ensure embryonic development towards masculinization, ensure and maintain the formation of secondary sexual characteristics during puberty, ensure and maintain the development of reproductive organs and accessory glands and the generation of libido, and ensure adult male libido, sexual behavior, sexual ability and sperm production. Therefore, they are known as the energy source of sex.
The testicles are solid organs, delicate and fragile, and located on the surface of the body. Despite the protection of the scrotum, they are easily damaged by external factors. In daily life, it's important to avoid impacts, falls, injuries, and blows. Furthermore, physical factors such as radiation and microwaves, as well as chemical substances like formaldehyde, pesticides, environmental pollutants, and estrogen, can also damage testicular function. Unhealthy lifestyle habits such as smoking, excessive alcohol consumption, prolonged sleep deprivation, consuming cottonseed oil, and eating large amounts of spicy and pickled foods can also lead to decreased testicular function. Additionally, it's particularly important to note that wearing tight pants for extended periods, frequent hot baths, and even prolonged sitting, common among drivers and office workers, can all impair local blood supply to the testicles and cause decreased testicular function.
During male development, the testes are located in the retroperitoneal space in the early embryonic stage. After the second month of embryonic development, the testes begin to gradually descend, usually entering the scrotum around the end of the eighth month. In some cases, the testes don't descend into the scrotum until some time after birth. The reason for this is that only the scrotum can provide the optimal environment for testicular growth and development.
The epididymis, composed of efferent ductules and epididymal ducts, functions to reabsorb and secrete testicular fluid. It reabsorbs the incoming testicular fluid and secretes glycerophosphate choline, glycoproteins, sterols, and sialic acid, providing a suitable internal environment for sperm maturation, storage, and processing. The epididymis is a pair of slender, flattened organs located above and behind the testis, lateral to the posterior border of the testis. The testis and epididymis are connected by the efferent ductules. The epididymis is mainly composed of epididymal ducts, which are irregularly shaped, fibrous tubules, approximately 6 cm long and 0.5 cm in diameter. The upper end of the epididymis is enlarged and blunted, called the head of the epididymis, which covers the upper part of the testis. The epididymis resembles a silkworm resting on an egg.
The epididymis acts as a "nanny" for sperm, its main physiological function being the transport and storage of sperm. Sperm newly produced in the testes are like newborn babies, very delicate and lacking the ability to fertilize a woman's egg. Sperm must remain in the epididymis for a period of time and undergo a series of maturation changes before acquiring motility and fertilization capacity. The epididymis is part of the vas deferens, and its tail also serves as a sperm storage site. Sperm must remain in the epididymis for 8–17 days to mature and acquire fertilization capacity.
The epididymis has secretory functions and plays multiple roles in sperm production. The epididymal epithelium synthesizes and secretes various substances. Glycerol-phosphocholine secreted by the epididymis can be used as an energy source by sperm after entering the female reproductive tract. The epididymal epithelium secretes various glycoproteins, which are crucial for sperm maturation and storage. These include prokinetic proteins that promote sperm motility and heterologous epididymal proteins (kinases) that inhibit sperm motility and store sperm in a resting state in the tail of the epididymis. Furthermore, the epididymis secretes various proteases, which may be related to masking specific antigens on the sperm surface. Sialic acid secreted by the epididymis not only masks specific antigens on the sperm surface to avoid autoimmune reactions but also plays an important role in maintaining the stability of the sperm acrosome and the integrity of its membrane structure, thus preventing sperm from being destroyed by immune cells. Dihydrotestosterone synthesized by the epididymal epithelium also promotes sperm maturation.
The epididymis also acts as a "scavenger" for sperm. If mature sperm are not ejaculated promptly, they will be stored in the tail of the epididymis. Sperm can survive there for 1-2 months. Sperm that have accumulated for too long and become aging will be engulfed and eliminated by the body's macrophages.