Aspects of Praematurity and Dysmaturity

Groningen 10–12 May 1967

Nonfiction, Health & Well Being, Medical, Specialties, Pediatrics, Gynecology & Obstetrics
Cover of the book Aspects of Praematurity and Dysmaturity by , Springer Netherlands
View on Amazon View on AbeBooks View on Kobo View on B.Depository View on eBay View on Walmart
Author: ISBN: 9789401034289
Publisher: Springer Netherlands Publication: December 6, 2012
Imprint: Springer Language: English
Author:
ISBN: 9789401034289
Publisher: Springer Netherlands
Publication: December 6, 2012
Imprint: Springer
Language: English

The concept of the foeto-placental unit as an integrated endocrine organ has been defined recently by many in vivo studies at the 17th- 20th week of gestation. A functioning foeto-placental unit is necessary for most of the increased oestrogen production of pregnancy and for the provision of glucocorticoids and aldosterone to the foetus. Neither the foetus nor the placenta alone have the necessary enzyme systems for the synthesis of these groups of steroids. However, when the foetus and placenta function as a unit, all of the enzyme systems are present for the synthesis of these steroids from circulating cholesterol. The placenta, but not the mid-gestation foetal adrenal, can synthesize physiologically significant amounts of pregnenolone from circulating cholesterol. Part of the pregnenolone is converted to progesterone in the placenta by the 3~-HSD system (absent in the foetus). The progesterone is transferred to the foetus where it is transformed by C-II, C-17, C-18 and C-21 hydroxylases (all absent in the placenta) to cortisol, corticosterone and aldosterone. Pregnenolone transferred from the placenta to the foetus undergoes 171X-hydroxylation, side­ chain splitting and sulfurylation (absent in the placenta) and is converted to DHAS. The DHAS may undergo 161X-hydroxylation (absent in the placenta) in the foetal liver and be transported to the placenta as 161X-OH-DHAS. There it is subjected to a neutral steroid sulfatase (absent in the foetus) and is converted to oestriol by action of the 3~-HSD system and the aromatizing enzyme system.

View on Amazon View on AbeBooks View on Kobo View on B.Depository View on eBay View on Walmart

The concept of the foeto-placental unit as an integrated endocrine organ has been defined recently by many in vivo studies at the 17th- 20th week of gestation. A functioning foeto-placental unit is necessary for most of the increased oestrogen production of pregnancy and for the provision of glucocorticoids and aldosterone to the foetus. Neither the foetus nor the placenta alone have the necessary enzyme systems for the synthesis of these groups of steroids. However, when the foetus and placenta function as a unit, all of the enzyme systems are present for the synthesis of these steroids from circulating cholesterol. The placenta, but not the mid-gestation foetal adrenal, can synthesize physiologically significant amounts of pregnenolone from circulating cholesterol. Part of the pregnenolone is converted to progesterone in the placenta by the 3~-HSD system (absent in the foetus). The progesterone is transferred to the foetus where it is transformed by C-II, C-17, C-18 and C-21 hydroxylases (all absent in the placenta) to cortisol, corticosterone and aldosterone. Pregnenolone transferred from the placenta to the foetus undergoes 171X-hydroxylation, side­ chain splitting and sulfurylation (absent in the placenta) and is converted to DHAS. The DHAS may undergo 161X-hydroxylation (absent in the placenta) in the foetal liver and be transported to the placenta as 161X-OH-DHAS. There it is subjected to a neutral steroid sulfatase (absent in the foetus) and is converted to oestriol by action of the 3~-HSD system and the aromatizing enzyme system.

More books from Springer Netherlands

Cover of the book Sustaining Young Forest Communities by
Cover of the book Recursive Functions and Metamathematics by
Cover of the book Husserl's Logical Investigations Reconsidered by
Cover of the book Colour Atlas of Mesothelioma by
Cover of the book Critical Voices in Teacher Education by
Cover of the book Urban Environment by
Cover of the book Metabolic Processes in the Foetus and Newborn Infant by
Cover of the book Radar Remote Sensing of Urban Areas by
Cover of the book Test Policy in Defense by
Cover of the book The Low Countries History Yearbook 1979 by
Cover of the book Justice and Health Care by
Cover of the book Salvation from Despair by
Cover of the book Essentials of Risk Theory by
Cover of the book Advanced Mathematical Thinking by
Cover of the book Integrated Catastrophe Risk Modeling by
We use our own "cookies" and third party cookies to improve services and to see statistical information. By using this website, you agree to our Privacy Policy