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Concept
Gonadal dysgenesis
Résumé
Gonadal dysgenesis is classified as any congenital developmental disorder of the reproductive system
in humans. It is atypical development of gonads in an embryo,. One type of gonadal dysgenesis is the development of functionless, fibrous tissue, termed streak gonads, instead of reproductive tissue. Streak gonads are a form of aplasia, resulting in hormonal failure that manifests as sexual infantism and infertility, with no initiation of puberty and secondary sex characteristics.
Gonadal development is a process, which is primarily controlled genetically by the chromosomal sex (XX or XY), which directs the formation of the gonad (ovary or testis).
Differentiation of the gonads requires a tightly regulated cascade of genetic, molecular and morphogenic events.
At the formation of the developed gonad, steroid production influences local and distant receptors for continued morphological and biochemical changes.
This results in the phenotype corresponding to the karyotype (46,XX for females and 46,XY for males).
Gonadal dysgenesis arises from a difference in signalling in this tightly regulated process during early foetal development.
Manifestations of gonadal dysgenesis are dependent on the aetiology and severity of the underlying causes.
Pure gonadal dysgenesis 46,XX also known as XX gonadal dysgenesis
Pure gonadal dysgenesis 46,XY also known as XY gonadal dysgenesis
Mixed gonadal dysgenesis also known as partial gonadal dysgenesis, and 45,X/46,XY mosaicism
Turner syndrome also known as 45,X or 45,X0
Endocrine disruptions
XX gonadal dysgenesis
46,XX gonadal dysgenesis is characteristic of female hypogonadism with a karyotype of 46,XX. Streak ovaries are present with non-functional tissues unable to produce the required sex steroid oestrogen.
Low levels of oestrogen effect the HPG axis with no feedback to the anterior pituitary to inhibit the secretion of FSH and LH.
FSH and LH are secreted at elevated levels. Increased levels of these hormones will cause to not start puberty, not undergo menarche, and not develop secondary sex characteristics.
Source officielle
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