Cytochrome P450 (CYP) and hydroxysteroid dehydrogenase enzymes are involved in the conversion of cholesterol to steroid hormones. These enzymes are primarily expressed in the placenta, adrenal and gonads. Interestingly, some of these enzyme activities have been demonstrated in non-endocrine tissues, where they may be involved in important paracrine and autocrine actions. This is particularly the case in the human fetus where steroid precursors circulate at high levels and could be metabolized within tissues to produce active steroid hormones. Herein, we tested the hypothesis that transcripts for steroidogenic enzymes are expressed in fetal tissues other than the classical steroidogenic organs. To test this hypothesis, real-time reverse transcription polymerase chain reaction (RT-RTPCR) assays were developed that quantify mRNA levels for steroidogenic acute regulatory protein (StAR), cholesterol side-chain cleavage (CYP11A), 3β-hydroxysteroid dehydrogenase types 1 and 2 (HSD3B1 and HSD3B2), 17α-hydroxylase (CYP17), 21-hydroxylase (CYP21), 11β-hydroxylase (CYP11B1), aldosterone synthase (CYP11B2) and aromatase (CYP19). The use of RT-RTPCR allows the specific detection of these transcripts at levels that would not be detectable using northern analysis. In addition, this method can detect levels of transcript that would not lead to sufficient protein for detection of enzymatic activity of protein by western analysis. Thus, this methodology can detect low levels of expression that could play a role in regulating intra-tissue concentrations of steroid hormone. Total RNAs used for RT-RTPCR analysis were isolated from several human fetal tissues, including adrenal, testis, ovary, placenta, aorta, brain, liver, kidney, heart, lung, pancreas, prostate, stomach, and thymus. Our findings suggest that RT-RTPCR is a powerful tool for the examination of steroidogenic enzyme mRNA expressions. Using this approach, we have identified and quantified transcript levels of StAR and steroidogenic enzymes in several endocrine and non-endocrine fetal tissues. Even though some of the mRNA levels measured in these peripheral tissues are extremely lower in respect to the steroidogenic tissues, they could be sufficient to produce local (. autocrine and paracrine) effects because produced steroids are not diluted into the entire circulation. These findings open new perspectives on the role of steroid hormones synthesized locally as probable regulatory factors of the development of several organ systems.
The StAR protein was first identified, characterized and named by Dr. Douglas Stocco at Texas Tech University Health Sciences Center in 1994.  The role of this protein in lipoid CAH was confirmed the following year in collaboration with Dr. Walter Miller at the University of California, San Francisco .  All of this work follows the initial observations of the appearance of this protein and its phosphorylated form coincident with factors that caused steroid production by Dr. Nanette Orme-Johnson while at Tufts University . 
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.