The Oestrous Cycle

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What is the Oestrous cycle?
It is the Reproductive cycle of most mammals
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What is the main difference between the Oestrous cycle and Menstrual cycle?
During the Oestrous cycle is pregnancy does not occur the Endometrium is re-absorbed rather than shed as in the Menstrual cycle.
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What does Polyoestrous mean?
Polyoestrous mammals are those that have more than one oestrous cycle a year
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What does monoestrous mean?
Monoestrous mammals are those that have a singular oestrous cycle a year
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Can you give an example of two Monoestrous mammals and two Polyoestrous mammals?
Monoestrous: dogs and bears / Polyoestrous: Rabbits and Rats
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What are the two phases of the Oestrous cycle?
Follicular phase and Luteal phase
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What percentage of the Oestrous cycle is made up by the follicular phase and what are the sub-divisions?
The follicular phase makes up 20% of the Oestrous cycle and can be divided into the Proestrus phase and Oestrus phase.
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What are the sub-divisions of the Luteal phase?
Metoestrus and Dioestrus
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What is the Proestrus phase?
Proestrus is when the mammal is not sexually receptive. During this phase Gnrh stimulates the production of FSH to increase the growth of the follicle. The increase in FSH stimulates the production of Oestrogen
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What is the Oestrus phase?
Oestrus is when the mammal is sexually receptive/ 'in heat'. Oestrogen levels peak and LH surge triggers ovulation. The primary oocyte that what contained in the follicle is released as it ruptures and enters the secondary oocyte stage.
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What are the signs of 'heat'?
Signs of heat include: Swollen and reddened *****, Mucous discharge, bellowing, restlessness and rubbed tailhead hair (cows and cattle).
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What is the Metoestrus phase?
Metoestrus is the end of sexual receptivity. Levels of Oestrogen decrease whilst levels of Progesterone increase due to the formation of the Corpus Luteum from the ruptured follicle. The Endometrium thickens and prepares for implantation.
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What is the Dioestrus phase?
Dioestrus phase is a short period of sexual inactivity before the next cycle, starting at the Proestrus phase.
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What is the Anoestrus phase?
Anoestrus phase is a long period of sexual inactivity between cycles. During Anoestrus the Uterine tubes and Vagina shrink until the next season.
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What happens if pregnancy does not occur?
If pregnancy does not occur the Corpus Luteum goes into a phase called Luteolysis. This is the deflation of the Corpus Luteum.
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What happens to the hormones during Luteolysis?
During Luteolysis the levels of progesterone decrease, releasing the Hypothalamus and Pituitary Gland from negative feedback inhibition. This allows the production of Gnrh which stimulates FSH and LH etc, starting a new cycle.
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Other cards in this set

Card 2

Front

What is the main difference between the Oestrous cycle and Menstrual cycle?

Back

During the Oestrous cycle is pregnancy does not occur the Endometrium is re-absorbed rather than shed as in the Menstrual cycle.

Card 3

Front

What does Polyoestrous mean?

Back

Preview of the front of card 3

Card 4

Front

What does monoestrous mean?

Back

Preview of the front of card 4

Card 5

Front

Can you give an example of two Monoestrous mammals and two Polyoestrous mammals?

Back

Preview of the front of card 5
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