Human Anatomy - Kotsan I. Ya. 2009

Urogenital System
Genitals - External Female Genitals
Anomalies of the Urogenital System Development

Developmental anomalies of the Urinary Organs. Renal developmental anomalies are generally classified into those related to the number, anatomical Location (position), and shape of the Kidneys.

Variations in renal count include supernumerary kidneys (an additional Kidney located over the spine between or inferior to the primary ones) or renal agenesis, which may be unilateral (accompanied by pronounced compensatory Hypertrophy of the single remaining kidney) or bilateral. A duplicated kidney arises when the mesonephric primordium splits into two equal parts on one side.

In certain instances, Congenital Renal Anomalies are associated with abnormal positioning. When a kidney fails to ascend to its normal anatomical site during Embryogenesis, remaining significantly lower, the condition is known as renal dystopia.

Renal anomalies can also affect shape. Fusion of the upper or lower poles of the kidneys results in a Horseshoe kidney. When both the lower and upper poles of the right and left kidneys fuse entirely, a ring-shaped (disc) kidney is formed.

A congenital cystic kidney develops due to impaired morphogenesis of the renal tubules and glomerular capsules, which persist within the renal parenchyma as isolated vesicles.

Ureteral anomalies most commonly manifest as unilateral or bilateral duplication. Less frequently, Ureters may exhibit cranial or caudal branching. Occasionally, narrowing or dilation of the ureteral lumen, or a localized outpouching of its wall (ureteral diverticulum), is observed.

Anomalies of the Urinary Bladder include bladder exstrophy, characterized by the absence of the anterior abdominal and bladder walls, typically accompanied by pubic bone diastasis. In some cases, a bladder diverticulum (an outpouching of the bladder wall) may be detected; even more rarely, a septum divides the bladder into separate chambers, resulting in a bilobed (two-chambered) bladder.

Urethral developmental anomalies most frequently present as hypospadias (absence of the ventral/lower urethral wall) or epispadias (absence of the dorsal/upper urethral wall). In some cases, the urethral meatus opens abnormally onto the Scrotum, the ROOT or shaft of the Penis, or the corona. Occasionally, congenital Valves are found within the urethral lumen.

Anomalies of the Male reproductive organs. Developmental defects of the internal and External Male Genitalia arise from complex morphogenetic transformations during embryogenesis. Male sex differentiation requires androgenic Hormones produced by the embryonic Testes. In the absence of androgens, impaired hormone synthesis, or peripheral receptor insensitivity during embryogenesis, the external genitalia may develop along female lines or manifest various anomalies. Furthermore, endogenous or exogenous embryotoxic insults can also lead to genital malformations.

Testicular anomalies are categorized into disorders of number, Structure, and position.

Anomalies of testicular number:

Anorchia (anorchism) is the Congenital absence of both testes, resulting from gonadal injury during early embryonic development. Anorchia is characterized by underdeveloped external genitalia, absence of the Prostate Gland and Seminal Vesicles, and poorly developed or absent secondary sexual characteristics.

Monorchia is the congenital absence of one Testis along with its Epididymis and vas deferens, typically resulting in hypoplasia of the corresponding hemiscrotum.

Polyorchia refers to the presence of more than two testes. Supernumerary testes in such cases should generally be excised due to their underdeveloped state and increased malignant potential.

Anomalies of testicular structure:

Testicular hypoplasia denotes the underdevelopment of the Gonads during the Embryonic period. This pathology is characterized by reduced dimensions of the testes, penis, and prostate, accompanied by pseudogynecomastia and delayed sexual maturation.

Testicular feminization syndrome (Androgen Insensitivity Syndrome) is a developmental anomaly occurring in individuals with a male karyotype (46,XY) and a female phenotype. Affected individuals possess female external genitalia, but lack a Uterus and fallopian tubes; the Vagina is hypoplastic and ends in a blind pouch. The testes may be located within the Labia Majora, inguinal canals, or Abdominal cavity. They produce normal levels of androgens and elevated levels of estrogens.

Hermaphroditism (intersexuality) is an anomaly characterized by the coexistence of reproductive traits of both sexes in a single individual. It is subdivided into true and pseudohermaphroditism. True hermaphroditism involves the presence of both ovarian and testicular Tissues (either separate gonads or a combined ovotestis). The external genitalia exhibit predominantly male or female features. The morphological phenotype is determined by the hormonal activity of the predominant gonadal tissue during Puberty. Pseudohermaphroditism arises from prenatal degenerative Changes in the testes, leading to female or intersexual Development of the external genitalia in genetic males possessing testes.

Anomalies of testicular position:

Cryptorchidism is the failure of the testes to descend into the scrotum, diagnosed in 10–20% of newborn males. During fetal development, the testes are initially located in the upper abdomen. By the end of the seventh month, they descend to the internal inguinal ring; during the eighth month, they traverse the inguinal canals, and by the middle of the ninth month, they settle into the scrotal sac. When descent is arrested in the abdominal cavity or Inguinal Canal due to endocrine, genetic, or mechanical factors, the condition is termed true cryptorchidism. In cases where the testis resides in the inguinal canal but can be manually manipulated into the scrotum under specific conditions (such as a warm bath) or descends spontaneously, it is classified as false (retractile) cryptorchidism.

Testicular ectopia refers to a deviation of the testis from its normal pathway of descent into the scrotum. Occasionally, after exiting the abdominal cavity via the inguinal canal, the testis deviates to an abnormal subcutaneous location (such as the Perineum, thigh, or groin). Transverse ectopia, where both testes occupy the same hemiscrotum, is rare. Compared to cryptorchidism, ectopic testes are generally more anatomically normal, and affected individuals typically do not exhibit eunuchoidism or hormonal deficiency.

Other congenital anomalies of the male internal genitalia may include the absence of the epididymis, vas deferens, or seminal vesicles.

Anomalies of the penis include hypoplasia of one or both corpora cavernosa and, in certain cases, pathological narrowing of the prepuce (phimosis), wherein the foreskin cannot be retracted behind the glans penis past the coronal sulcus in children older than 5–6 years. Rare instances of penile duplication (diphallia) or complete penile agenesis (aphallia) also occur, the latter typically associated with other lethal Congenital Malformations.

Scrotal anomalies include hypoplasia (underdevelopment), which typically occurs in association with cryptorchidism when the testes fail to descend into the scrotal sac by birth.

Developmental anomalies of the FEMALE REPRODUCTIVE ORGANS. During ovarian development, abnormal displacement—known as ovarian ectopia—may also occur. In this condition, one or both Ovaries are located near the deep inguinal ring or descend through the inguinal canal to lie subcutaneously within the labia majora.

An accessory Ovary occurs in 4% of cases. Underdevelopment of one or both ovaries is occasionally observed.

Absence of one or both fallopian tubes, as well as occlusion of their abdominal or uterine ostia, is extremely rare.

Incomplete fusion of the distal ends of the right and left paramesonephric ducts results in a bicornuate uterus, whereas complete non-fusion leads to a double uterus and double vagina. Retarded development of the paramesonephric duct on one side produces an asymmetric unicornuate uterus. It is not uncommon for uterine development to be arrested; such a uterus is referred to as infantile (hypoplastic). Abnormal positioning of the uterus is also encountered, such as a marked lateral displacement or a retroflexion, where the uterine body is angulated relative to the cervix backward toward the spine rather than forward.