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100
How much of the cycle is the Luteal Phase?
80% of the cycle
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What are the 2 subphases of the Luteal Phase?
Metestrus and Diestrus
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How long is estrus?
Depends on species, 6 to 24 hours in cattle
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Are females actually sexually receptive throughout estrus?
No, standing estrus at the end is the only actual sexually receptive time
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What is Metestrus characterized by?
Massive cell remodeling called luteinization
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What does the Luteal Phase entail?
The period from ovulation (follicle going away) to corpora luteum regression (corpus luteum going away)
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When does Proestrus begin?
When Progesterone declines with luteolysis
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What characterizes estrus?
Visible behavior symptoms: "sexual receptivity"
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What is lordosis?
Mating posture characterized by an arched back
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What is Diestrus?
the longest stage of the estrus cycle
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What is the dominant hormone in the Luteal phase, and why?
Progesterone - promotes gestation - gets rid of the follicle
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How long is Proestrus?
2 to 5 days
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What controls estrus and why?
Controlled by estradiol - increased levels = larger follicle - good unless follicle becomes too large and causes follicular cyst
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What is Metestrus?
The period between ovulation and a functional corpus luteum
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What is diestrus characterized by?
Fully functional Corpus Luteum and high levels of progesterone
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Can you label all of the pinked-out segments of this image?
400
What characterizes proestrus?
Characterized by major endocrine transition - controlled by FSH and LH
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What are the behavioral signs of estrus - why are these important?
Increased locomotion (finding male)
vocalization (signaling male)
nervousness
mounting attempts
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How long is metestrus?
2 to 5 days in length
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How long does Diestrus last?
10-14 days in polyestrus females
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What are the 2 subphases of the Follicular Phase?
Proestrus and Estrus
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What is present during proestrus and why?
Developing follicles are present because you want them to take over as the dominant follicle
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What is standing estrus?
The actual receptive period near the end of estrus, right before ovulation
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What hormones are low during metestrus?
early on, both estrogen and progesterone are low
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Is there any sexual receptivity in Diestrus?
No