Table 2.

Indicators of sexual maturation and endocrine disruption in rodent models.

Sexual Maturation
Preputial Separation	The separation of the foreskin of the penis from the glans, preputial separation (PPS) is an early marker of the progression of puberty.
Vaginal Opening	The initial marker of the rise in circulating estrogen that signifies the onset of puberty and first ovulation followed by the start of estrous cycling.
Endocrine Disruption
Anogenital Distance (AGD)	The distance between the anus and genital protuberance in newborns of various species including mouse and rat is used as the sole external sex-differentiating marker (longer in males compared to females) and is used to determine whether or not endocrine disruption has occurred. Under-masculinization is said to have occurred if AGD is shortened compared to control animals.
Sex Organ Histology	Changes in morphology of the mammary gland, ovary, uterus, testes are indicators of estrogenic effects that may ultimately be manifested as enhanced or reduced fertility.
Sex Organ Weight	Higher weight of uterus, ovaries, testes, or prostate may indicate estrogenic effects due to higher rates of cell proliferation within the organ.
Serum Hormones	Measurement of sex steroid hormones (i.e., LH, FSH, GnRH, estradiol, progesterone, testosterone) demonstrates estrogenic perturbations in the endocrine system.
Estrogen Receptor Activity	Elevated transcription of ER-ß or ER-α is indicative of higher estrogenic activity.
Estrous Cycle	Length of time spent in each phase of estrous cycle can be used to understand if fertility may be altered, i.e., if an animal is in prolonged diestrus, lower fertility may result.
Lordosis Quotient	A measure of sexual behavior and is calculated by dividing the number of lordoses (inward curving of a portion of the vertebral column) by the number of mounts.