Anti-Müllerian hormone (AMH) is a
dimeric glycoprotein that inhibits the development of the
Müllerian ducts in a male
embryo. It is named after
Johannes Peter Müller. It has also been called Müllerian inhibiting factor (MIF), Müllerian inhibiting hormone (MIH), and Müllerian inhibiting substance (MIS).
Structure
AMH is a
protein hormone structurally related to
inhibin and
activin, and a member of the
transforming growth factor-β (TGF-β) family. It is present in
fish,
reptiles,
birds,
marsupials, and placental
mammals.
Gene
In humans the
gene for AMH is
AMH, on
chromosome 19p13.3, while the gene
AMH-RII codes for its
receptor on
chromosome 12.
Functions
Embryogenesis
In mammals AMH is secreted by
Sertoli cells of the
testes during
embryogenesis of the fetal male and prevents the development of the
mullerian ducts into the
uterus and other mullerian structures. The effect is ipsilateral, that is each testis suppresses Müllerian development only on its own side. In humans this action takes place by 8 weeks gestation. In female
embryogenesis the absence of AMH allows for the development of upper
vagina,
uterus and
cervix, and
oviducts.
Amounts of AMH that are measurable in the blood vary by age and sex. AMH works by interacting with specific
receptors on the surfaces of the cells of target tissues. The best known and most specific effect, mediated through the AMH type II receptors, includes programmed cell death (
apoptosis) of the target tissue (the fetal mullerian ducts).
Ovarian function
While AMH is measurable in males during childhood and adulthood, AMH cannot be detected in women until
puberty. AMH is expressed by
granulosa cells of the
ovary in the reproductive age and controls the formation of primary follicles by inhibiting excessive follicular recruitment by FSH. It therefore has a role in folliculogenesis,
and some authorities suggest it is a measure of some aspects of ovarian function useful in assessing conditions such as
polycystic ovary syndrome and
premature ovarian failure.
Other functions
AMH production by the
Sertoli cells of the testes remains high throughout childhood but declines to low levels during puberty and adult life. AMH measurements have become widely used in the last few years in the evaluation of testicular presence and function in infants with
intersex conditions,
ambiguous genitalia, and
cryptorchidism.
Pathology
In men, inadequate embryonal AMH activity can lead to the
Persistent Müllerian duct syndrome (PMDS), in which a rudimentary uterus is present and testes are usually
undescended. The AMH gene (
AMH) or the gene (
AMH-RII) for its receptor are usually abnormal.
Research
AMH has been synthesized. Its ability to inhibit growth of tissue derived from the Müllerian ducts has raised hopes of usefulness in the treatment of a variety of medical conditions including
endometriosis,
adenomyosis and uterine
cancer. Research is underway in several laboratories.
AMH assessment is also useful in fertility assessment as it provides a guide to Ovarian Reserve and identifies women who may need to consider either egg freezing or trying for a pregnancy sooner rather than later if their long term future fertility is poor. Measuring AMH alone may be misleading as high levels occur in conditions like Polycystic Ovarian Syndrome and therefore AMH levels should be considered in conjunction with a transvaginal scan of the ovaries to assess antral follicle count.
See also
Footnotes
