Thyroid hormones steroids

Cells of the zona fasciculata and zona reticularis lack aldosterone synthase (CYP11B2) that converts corticosterone to aldosterone, and thus these tissues produce only the weak mineralocorticoid corticosterone. However, both these zones do contain the CYP17A1 missing in zona glomerulosa and thus produce the major glucocorticoid, cortisol. Zona fasciculata and zona reticularis cells also contain CYP17A1, whose 17,20-lyase activity is responsible for producing the androgens, dehydroepiandosterone (DHEA) and androstenedione. Thus, fasciculata and reticularis cells can make corticosteroids and the adrenal androgens, but not aldosterone.

Female ovaries are two almond shaped glands on each side of the uterus. They have three main functions; (i) Containing immature ova (eggs), (ii) The secretion of oestrogen, and (ii) the secretion of progesterone. Ostrogen is secreted by the adrenal cortex as well as the ovaries, and is present in the blood of all females from puberty through to the menopause. oestrogen acts on the structure of the reproductive organs, especially during the menstrual cycle. This induces and maintains female secondary sexual characteristics. Progesterone works on the uterus to prepare it for the implantation of a fertilised ovum (egg). It causes the development of the breasts, and is essential for the complete development of the maternal proportion of the placenta.

Thyroid hormones steroids

thyroid hormones steroids


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