Sex steroids, also known as gonadocorticoids and gonadal steroids, are steroid hormones that interact with vertebrate steroid hormone receptors.The sex steroids include the androgens, estrogens, and progestogens. Their effects are mediated by slow genomic mechanisms through nuclear receptors as well as by fast nongenomic mechanisms through membrane-associated receptors and signaling cascades. The term sex hormone is nearly always synonymous with sex steroid. The polypeptide hormones luteinizing hormone, follicle-stimulating hormone and gonadotropin-releasing hormone are usually not regarded as sex hormones, although they play major sex-related roles. the two main classes of sex steroids are androgens and estrogens, of which the most important human derivatives are testosterone and estradiol, respectively. Other contexts will include progestogens as a third class of sex steroids, distinct from androgens and estrogens. Progesterone is the most important and only naturally occurring human progestogen. In general, androgens are considered "male sex hormones", since they have masculinizing effects, while estrogens and progestogens are considered "female sex hormones" although all types are present in each sex at different levels.