*VSSHypothalamo-hypophysial-Gonadal AxisV. Sutarmo Setiadji*

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*VSSPosition of Pituitary gland*

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Hormone:

Produced by cells or endocrine glands, are secreted into the blood stream and act at a distance from their site of origin

Target cells of the hormone are cells which have receptors to the specific hormone

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Hypothalamic control to pituitary gland:(through hypophysiotropic hormones:

CRH (corticotropin releasing hormone) TRH (thyrotropin releasing hormone) GRH (growth hormone releasing hormone) GIH (growth hormone inhibiting hormone, or somatostatin) GnRH (gonadotropin releasing hormone) PIH (prolactin inhibiting hormone) PRH (prolactin releasing hormone)

*VSS*In human, no new ova are formed after birth. During fetal development, the ovaries contain over 7 million premordial follicles atresia before and after birth.

At birth 2 million of ova 50% atresia.

At puberty < 300.000 ova only about500 reaches maturity during reproductivelife.

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*VSS*Theca interna cells have many LH receptors.LH acts via cAMP to increase conversions of cholesterol to androstenedione.

Granulosa cells make estradiol when provided with androgen secreted into the follicular fluid.Granulosa cells have many FSH receptors. FSH facilitates secretion of estradiol by acting via cAMP to increase aromatase activity.

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*VSS*Mature granulosa cells also have LH receptors, and LH also stimulates estradiol production.

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