Afferent nerve endings in the bladder wall are important in conveying the sensations associated with degrees of bladder fullness and also bladder pain to the spinal cord. This chapter discusses the peripheral control of micturition, cellular signaling pathways in normal bladder function, spinal control of bladder function, and interoceptive sensations. Acetylcholine (ACh) and adenosine triphosphate (ATP) are released by the bladder urothelium during urine storage, in increasing concentrations as the bladder wall distends. Muscarinic, nicotinic and purinergic receptors have been identified in the bladder urothelium and/or suburothelium in human or animal studies. In normal adults information about the bladder is passed from the periaqueductal gray (PAG) to higher regions of the brain. This type of interoception is mediated by afferent input through small-diameter fibers in lamina 1 of the spinal cord. A number of spinal reflex mechanisms are involved in the control of the urethro-vesical unit.

Ovarian volume decreases significantly in each 10-year period of a woman's fertile life. The ovarian size decreases in women greater than 40 years old. The volume of each ovary is calculated by measuring in three perpendicular directions and applying the formula for an ellipsoid. Using the largest cross-sectional sagittal view of the ovary, the mean ovarian diameter could be calculated from measurement of two perpendicular diameters. The combination of transvaginal ultrasound and pulsed color Doppler is increasingly used in gynecology to assess the hemodynamic changes in various physiological and pathological situations of the pelvic organs. Only one study has compared the predictive value of antral follicle count (AFC) measurement made using both two-dimension and three-dimension ultrasound in determining the outcome of response to ovarian stimulation as measured by the number of follicles that develop, the number of oocytes retrieved, and the pregnancy rate following assisted reproductive technologies (ART).