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| | ==Introduction== | | ==Introduction== |
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| − | ==Female Sex Hormones==
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| − | '''Oestrogens''' are the hormones responsible for inducing oestrous in females. '''Estradiol''' is the principle oestrogen in the female.'''Estrone''' and '''Estriol''' are chemically similar to estradiol but are found in lower concentrations and have a lower estrogenic activity.
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| − | '''Progesterone''' is another crucial female sex hormone, produced by the corpus luteum. Progesterone prepares the uterus for reception of fertilised oocytes. Oestrogens and progesterone are transported via the blood bound to plasma proteins.
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| − | ===Hormone Production===
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| − | Production of oestrogens occurs in the ovary, placenta, adrenal cortex and in males in Sertoli cells found in the testes (see above). Estradiol is synthesised from cholestrol.
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| − | Progesterone is produced in the [[Corpus_Luteum_-_Anatomy_%26_Physiology|corpus luteum]], also using cholesterol as a base molecule. More detailed information regarding corpus luteum [[Corpus_Luteum_Formation_-_Anatomy_%26_Physiology|formation]] and [[Corpus_Luteum_Regression_-_Anatomy_%26_Physiology|regression]] please use the links.
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| − | ===Regulation of Female Sex Hormones===
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| − | ===Effects of Female Sex Hormones===
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| − | Oestrogens and progesterone exert their effects in a similar manner to testosterone by binding to a hormone receptor within the cytoplasm of the cell and then binding to DNA in the cell nucleus affecting DNA transcription.
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| − | Oestrogens have a number of functions related to reproduction and other areas of physiology. In relation to the reproductive role of oestrogens, they stimulate follicular growth and maturation, induce the female to begin displaying oestrous behaviour to facilitate mating, prepare the external genitalia for copulation and create favourable conditions for the development of fertilised egg cells. Oestrogens also contribute to the growth and development of mammary tissue and prepare the uterus for parturition.
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| − | Where oestrogens stimulate growth of follicles in the ovaries, oestrogens secreted from the ovary in the [[Oestrous_Cycle_-_Anatomy_%26_Physiology#Follicular_Phase|follicular phase]] ([[Oestrous_Cycle_-_Anatomy_%26_Physiology#Pro-Oestrus|proestrous]] and [[Oestrous_Cycle_-_Anatomy_%26_Physiology#Oestrus|oestrous]]) lead to hypertrophy of the epithelium and the endometrium. Secretory glands within the uterus enlarge and secretion is initiated leading to thickening of tissues. The blood vessels supplying the uterus and external genitalia dilate and blood flow to these areas increases significantly. Oedema occurs within the uterus and surrounding connective tissues. Oestrogen also causes increased uterine muscle tone. In the cervix oestrogens stimulate increased mucus secretion and the vaginal epithelium becomes keratinised.
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| − | Once near term, the concentration of progesterone decreases, altering the ratio between progesterone and oestrogen. This stimulates myometrial activity and prepares the uterus for parturition.
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