Steroid isolation , depending on context, is the isolation of chemical matter required for chemical structure elucidation, derivitzation or degradation chemistry, biological testing, and other research needs (generally milligrams to grams, but often more  or the isolation of "analytical quantities" of the substance of interest (where the focus is on identifying and quantifying the substance (for example, in biological tissue or fluid). The amount isolated depends on the analytical method, but is generally less than one microgram.  [ page needed ] The methods of isolation to achieve the two scales of product are distinct, but include extraction , precipitation, adsorption , chromatography , and crystallization . In both cases, the isolated substance is purified to chemical homogeneity; combined separation and analytical methods, such as LC-MS , are chosen to be "orthogonal"—achieving their separations based on distinct modes of interaction between substance and isolating matrix—to detect a single species in the pure sample. Structure determination refers to the methods to determine the chemical structure of an isolated pure steroid, using an evolving array of chemical and physical methods which have included NMR and small-molecule crystallography .  :10–19 Methods of analysis overlap both of the above areas, emphasizing analytical methods to determining if a steroid is present in a mixture and determining its quantity. 
Some authors state that the clitoral prepuce is formed by a splitting of the urogenital folds around the clitoris, with development of the prepuce superiorly and the clitoral frenulum inferiorly [ 34 ]. However, this theory is discordant with earlier studies [ 12 ] and has not been explicitly proved. The urogenital groove on the ventral surface of the clitoris prevents circumferential preputial development and results in the hoodlike appearance of the clitoral prepuce. The urogenital groove of the clitoris eventually regresses and develops into the labia minora [ 32 ]. In the female, there is no mesenchymal proliferation in the prepuce to form a dartos muscle layer. Physicians can allay parental fear of normal, intact external genitalia by explaining normal development and maturation. With this understanding, physicians will also be less likely to amputate normal, healthy genital tissue from children.