Placental gonadrotrophins
PLACENTAL GONADROTROPHINS
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The maintenance of the corpus leuteum of pregnancy in some species is favoured by the production of chorionic gonadotropin (CG) eg. human (hCG) from day 8
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in the mare the endomaterial cups produce a hormone (eCG) from day 40 to about day 150 (previously called pregnant mare serum gonadotropin (PMSG)).
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hCG contains more of LH than FSH, while eCG contains more of FSH than LH.
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hCG is mainly leutienising. In female animals this induces ovulation and reinforces the secretion of progesterone by the ovary.
Effects
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hCG will bind to LH receptors on the granulos, theca and luteal cells with high affinity and specificity.
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eCG has LH like activity only in the mare, but in the other species it has mainly FSH like activity.
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In the mare it only leutinize follicles already present in the ovary but, in the other species it stimulates follicular growth and ovulation.
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Serum gonadotrophin has been used to increase the number of developing follicle and ovulation and oestrus and thus increase the incidence of twins in cattle.
Uses
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It is used to control the time of ovulation in mares because in these animals ovulation normally occurs towards the end of a long estral period.
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It is widely used in the treatment of cystic ovarian disease especially where nymphomania is present and sometimes in the treatment of cyrptorchidism.
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In male animals chorionic gonadotropin is used to stimulate the secretion of testosterone by the testes.
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Last modified: Thursday, 26 April 2012, 5:13 AM