Sexually Transmitted Diseases - I. I. Mavrov 2005

Anatomical and Physiological Structure of the Reproductive System
Structural Features of Genital Organs in Children

A child's Reproductive System differs significantly in both Size and Structure from the adult anatomy. Throughout the first six years of life, the growth of reproductive Organs is minimal and does not keep pace with overall somatic development. Growth accelerates slightly thereafter, culminating in substantial developmental changes during Puberty at ages 14–15.

Anatomy of the Male reproductive organs

At birth, the child's Penis is fully formed. In newborns, it has an average length of 2–2.5 cm; by 4 years of age, it measures 2.5–3 cm; at 7 years, 4.5 cm; and by ages 16–18, it attains adult dimensions.

The prepuce ( foreskin) in newborns is longer and more prominent than in infants, remaining relatively narrow, which accounts for physiological phimosis. Numerous glands located on the inner surface of the prepuce and, in particular, on the glans penis, produce smegma.

In neonates, the inner mucosal layer of the prepuce is fused to the epithelial surface of the glans (their epithelial Cells do not undergo keratinization). By the age of 3, this adhesion typically extends to the urethral meatus; subsequently, under METABOLISM/18.html">The Influence of erections and manual manipulation, the adhesion recedes. By the 5th year of life, the glans is only half-covered, and by ages 8–10, it becomes completely exposed.

The length of the Urethra in newborn boys is 5–6 cm. It increases by an average of 0.5 cm annually, reaching 16–18 cm by age 16.

The mucous membrane of the pediatric urethra is smooth and devoid of folds. The urethral glands have exceptionally narrow excretory ducts—a vital protective feature that hinders the ascent of pathogens into the upper tract, thereby preventing complications. Consequently, while urethritis does occur in children, it typically follows a brief course and is rarely complicated by epididymitis or orchitis. However, the urethral mucosa in infants is extremely delicate throughout its length and tears easily.

In the neonate, the Scrotum forms a small pouch (4.5–3.5 cm) with lax walls. By the end of the first year, it rounds out and its walls become firmer. The scrotum retains this rounded shape through the first decade of life, and by age 15, it differentiates into a broader lower portion containing the Testes and a narrower superior neck.

Shortly before birth, the Testis descends into the scrotum, drawing the vas deferens along with it to assume its permanent position. Testes in neonates are relatively small; their growth then slows, remaining largely unchanged in size and mass During the first decade of life. A minor increase is observed between ages 10 and 14, and by 16–18 years, the testes reach maximum development, acquiring the Functional Characteristics of mature Gonads.

The testicular parenchyma in infants is relatively rich in Connective Tissue. The seminiferous tubules appear as solid cords due to the absence of lumens, which only form with the onset of Spermatogenesis.

The Epididymis is more pronounced in infants than in adults, accounting for more than half of the total testicular mass. Like the testis, the epididymis exhibits minimal growth during the first 10 years of life, expanding rapidly only during puberty.

The Spermatic Cord has a diameter of 14 mm in newborns and infants, 18 mm at age 15, and 20–25 mm in adults. The vas deferens is structurally comparable to that of an adult, doubling in length as the body grows. The Seminal Vesicle in infants is located more superiorly than in adult males, though its Morphology is similar. It grows slowly, undergoing significant enlargement only during puberty.

In the infant, the Prostate Gland consists predominantly of smooth Muscle and connective tissue; it is spherical, undivided into lobes, and lacks an isthmus. It assumes its characteristic chestnut shape only around ages 13–14. The average glandular mass is 0.82 g; it increases only slightly up to age 2, followed by marked growth between ages 6 and 16. The interior contains blind epithelial tubules; by age 12, the prostatic ducts begin to canalize and secretory activity intensifies, culminating in the opening of the excretory ducts of the tubulo-alveolar prostatic glands by ages 16–17.

Anatomy and PHYSIOLOGY OF THE FEMALE REPRODUCTIVE ORGANS

A distinctive anatomical feature of the genitalia in young girls is the presence of a posterior labial commissure of the Labia minora, a structure absent in adult women. Numerous minor glands are distributed across both the Labia Majora and minora, though they are frequently absent on the inner surface of the labia minora.

The vaginal vestibule is lined with stratified squamous epithelium. The minor vestibular glands are located predominantly around the external urethral meatus and are significantly more numerous in newborn girls than in adult women. The major vestibular glands (Bartholin's glands) begin to function at puberty, and by ages 10–12, their excretory ducts already exhibit a typical structure lined with columnar epithelium.

The urethra in newborn girls is 1–1.5 cm long; at 1 month, 1.6 cm; at 12 months, 2.2 cm; and at 16 years, 3.2 cm. The external urethral meatus opens into the vestibule 1–1.5 cm inferior to the Clitoris between the labia minora and has an oval or slit-like shape. The urethral mucosa in girls is rich in folds. Skene's glands and Morgagni's lacunae are distributed throughout the length of the urethra, though they are more concentrated in the anterior segment. Some of these open directly into the vaginal vestibule.

Ovaries grow slowly during childhood, and their mass increases progressively: it doubles by the end of the first year of life, increases 7-fold by age 6, and reaches 5–6 g by age 16 (a 20-fold increase compared to birth weight). In neonates, the ovaries are elongated and flattened with a smooth surface, weighing between 0.2 and 0.4 g. During the second year, they begin to assume an ovoid shape, achieving complete structural maturity by age 10.

The number of primordial follicles decreases with age: a 17-day-old infant has about 23 rows of follicles, whereas a 10-year-old girl has 6–8. During puberty, cortical follicles are found at various Selection/3.html">Stages of development. The uterine tubes do not elongate during childhood; their tortuosity diminishes by the 5th year of life as the transverse pelvic diameter increases. The ovarian ligaments stretch, allowing the ovaries to detach from the Uterus and assume their normal anatomical position.

At birth, a girl's uterus is approximately 4 cm long, with the body being twice as short as the cervix. Following birth, involution and a reduction in size occur due to the withdrawal of placental Hormones that had stimulated uterine growth. In infancy, the uterine length is 2.5–2.8 cm. Accelerated uterine growth begins after 7–8 years of age. With the onset of puberty, the uterus acquires the shape and dimensions characteristic of an adult woman.

Uterine glands are already present at birth. Their number varies considerably among individuals independently of the child's age. At 6 years of age, a small number of glands are located primarily in the uterine fundus. By age 10, their number increases, and after 12 years, they uniformly penetrate the entire endometrium.

In newborns, the Vagina reaches a length of 3 cm; the introitus is situated deeply, has a nearly vertical orientation, and appears somewhat funnel-shaped. The vaginal walls are closely apposed, and the musculature is poorly developed and lacking in elasticity. In one-year-old girls, the vaginal length is 4 cm. Vaginal rugae begin to appear around age 8. The absolute dimensions of the vagina increase rapidly after age 10, reaching a length of 7–8 cm by puberty.

In the newborn girl, the functional and morphological state of the vagina is governed by maternal placental hormones. The mucosa is well developed, the epithelium contains Glycogen, and the vaginal content is acidic. As placental estrogens decline from age 1 up to 10–12 years, glycogen production ceases, Döderlein's bacilli disappear, the pH shifts to alkaline (7–8), and consequently, the protective function of the vagina is lost while the epithelial lining thins.

In girls aged 12–14, the ovaries begin to synthesize endogenous Sex Hormones. The vaginal mucosa thickens, glycogen reappears, the environment becomes acidic, Döderlein's bacilli populate the vaginal flora, and the uterus enlarges—all of which signal the onset of puberty.