Anatomy and Physiology of Children and Adolescents - M. R. Sapin 2007

Urogenital System
Reproductive System
Male Genital Organs - Age-Related Features of the Male Genital Organs

Before Puberty (13–15 years of age), the Testis grows slowly, after which its development accelerates sharply. In a newborn, the length of the testis is 10 mm and its mass is 0.2 g. By the age of 14, the length of the testis increases by 2–2.5 times (reaching 20–25 mm), and its mass reaches 2 g. At 18–20 years, the length of the testis is 38–40 mm, and its mass increases up to 20 g. In adulthood (22 years and older), the size and mass of the testis change very little, and after 60 years they even decrease slightly. At all age periods, the right testis is larger and heavier than the left and is positioned higher. In newborns, the convoluted and straight seminiferous tubules, as well as the tubules of the rete testis, lack a lumen, which appears by the time of puberty. In adolescence, the diameter of the seminiferous tubules doubles. In adult men, it increases threefold compared to the diameter of the seminiferous tubules in newborns. By birth, the Testes should descend into the Scrotum. However, if testicular descent is delayed in a newborn, they may remain in the Inguinal Canal (retroperitoneally). In such cases, the testes descend into the scrotum later.

The Epididymis is relatively large. In a newborn, the length of the epididymis is 20 mm and its mass is 0.12 g. During puberty, the growth of the epididymis accelerates.

The Ductus deferens (vas deferens) in a newborn boy is very thin. The cremaster Muscle is poorly developed. The transverse diameter of the Spermatic Cord in a newborn is 4.0–4.5 mm. Up to 14–15 years of age, the spermatic cord and its constituent structures grow slowly, after which their growth accelerates. The thickness of the spermatic cord in a 15-year-old adolescent is approximately 6 mm, and the transverse diameter of the ductus deferens is 1.6 mm.

The Seminal Vesicles are poorly developed in newborns; their length is 1 mm and the cavity is very small. Up to 12–14 years of age, the seminal vesicles grow slowly, but during adolescence (13–16 years) their growth accelerates, and their size and cavity increase significantly. As age increases, THE POSITION OF the seminal vesicles changes. In newborns, they are located high up due to the high position of the Urinary Bladder, and are covered by the Peritoneum on all sides. By the age of 2, the vesicles descend and come to lie retroperitoneally. The peritoneum adjoins only their apices.

The Prostate Gland in newborns and infants is spherical because the right and left lobes are not yet distinct. The gland is located high, feels soft and glandular, and the parenchyma is not formed. Accelerated growth of the gland is observed after 10 years of age. By adolescence, the gland acquires the shape characteristic of an adult gland. The glandular parenchyma of the prostate also develops during adolescence, prostatic ductules are formed, and the gland acquires a dense consistency. The mass of the prostate gland in a newborn is 0.82 g, at 1–3 years — 1.5 g, during the second childhood period (8–12 years) — 1.9 g, and in adolescence (13–16 years) — 8.8 g.

The length of the Penis in a newborn is 2.0–2.5 cm, and the prepuce (foreskin) is long, completely covering the glans penis. Before puberty, the penis grows slowly, after which its growth accelerates. The male Urethra in newborns is relatively longer (5–6 cm) than in other age periods due to its high origin. Rapid growth of the urethra is observed during puberty.

The scrotum in newborns is small in size. It grows intensively during puberty.

Review and Self-Assessment Questions:

1. List (in sequential order) the pathways of male germ Cell (spermatozoa) transit from their site of formation to the urethra.

2. Name the locations of the prostate gland and Bulbourethral Glands. Describe their anatomical relationships with the urethra.

3. Describe the Structural Features of the cavernous bodies (corpora cavernosa) and the spongy body (corpus spongiosum) of the penis.