[Ontogenesis of vesico-sphincter function]

The muscles of the pelvic floor and perineum are crucial for supporting the pelvic organs, controlling continence, and aiding in sexual function, childbirth, and core stability. They are typically divided into the superficial perineal layer and the deep pelvic floor layer.
Perineal Layer
The perineum is a diamond-shaped area below the pelvic diaphragm, divided into an anterior urogenital triangle that contains the external genitals and a posterior anal triangle housing the anus. The urogenital...

Urine formation is an essential function of the human body. It plays a critical role in maintaining homeostasis by regulating the volume and composition of body fluids. The kidneys, the primary organs involved in this process, filter blood to remove waste products and excess substances, ultimately producing urine.
Glomerular Filtration
The first stage in urine formation is glomerular filtration. Each kidney contains approximately 1 million nephrons, the functional units of filtration, with a...

The urinary bladder is a hollow, muscular sac that temporarily stores urine before it is expelled from the body. It can hold approximately 600 mL of urine prior to micturition. The bladder is retroperitoneal and located behind the pubic symphysis in the pelvic floor.
In males, the bladder is situated in front of the rectum, while in females, it is positioned anterior to the vagina and uterus. The bladder floor contains an inverted triangular area called the trigone, defined by the two ureteric...

Urination, or micturition involves the coordination of the bladder's detrusor muscle and two sphincters to ensure controlled bladder emptying.
The process begins with bladder filling, where the bladder wall stretches as urine accumulates. This stretching activates the urine storage reflex, mediated by the sacral spinal segments and the pontine storage center. Efferent sympathetic impulses stimulate the detrusor muscle to relax and the internal urethral sphincter to contract, facilitating urine...

Development of the reproductive organs in an embryo starts from a bipotential state. This means the early embryo can develop either male or female reproductive organs. The formation of these organs begins with the growth of gonadal ridges that arise from the intermediate mesoderm during the fifth week of development.
Near the gonadal ridges, two duct systems are present: the mesonephric ducts (Wolffian ducts) and paramesonephric ducts (Müllerian ducts). These ducts form the basis for the male...

The lower urinary system consists of the urinary bladder and urethra, which are essential in storing and expelling urine from the body. Together with the internal and external sphincters, these structures work together to regulate urination effectively.Anatomy of the BladderThe urinary bladder is a muscular, stretchable organ behind the pubic bone and in front of the rectum. In females, the bladder is positioned anterior to the vagina and inferior to the uterus, while in males, it is located...