Difference between revisions of "Avian Breeding, Ovulation and Oviposition - Anatomy & Physiology"
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== Breeding Cycles == | == Breeding Cycles == | ||
* Classified according to length of cycle and the time of year when the species becomes reproductively active. | * Classified according to length of cycle and the time of year when the species becomes reproductively active. | ||
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* Usually lay one or more eggs in a clutch and terminate laying to incubate the eggs. | * Usually lay one or more eggs in a clutch and terminate laying to incubate the eggs. | ||
* Number of eggs per clutch and total number of clutches vary with species and season. | * Number of eggs per clutch and total number of clutches vary with species and season. | ||
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== Endocrine Control == | == Endocrine Control == | ||
* In females, '''FSH''' is mainly responsible for follicular growth. | * In females, '''FSH''' is mainly responsible for follicular growth. | ||
* Developing follicles produce '''Oestrogen''' from '''Theca and interstitial cells''' and '''Progesterone''' from '''Granulosa cells'''. | * Developing follicles produce '''Oestrogen''' from '''Theca and interstitial cells''' and '''Progesterone''' from '''Granulosa cells'''. | ||
| − | * Increasing levels of Oestrogen stimulate an '''LH surge''' to cause the [[ | + | * Increasing levels of Oestrogen stimulate an '''LH surge''' to cause the [[Follicles - Anatomy & Physiology|follicle]] to split and release the primary [[Oogenesis - Anatomy & Physiology|oocyte]]. |
| − | * '''Oestrogen mobilizes calcium''' from the bone, increasing plasma concentrations for [[ | + | * '''Oestrogen mobilizes calcium''' from the bone, increasing plasma concentrations for [[Egg Composition and Formation - Anatomy & Physiology|egg formation]]. |
* '''Progesterone''' secretion continues to inhibit further ovulation and stimulate behavioural changes associated with '''broodiness and incubation'''. | * '''Progesterone''' secretion continues to inhibit further ovulation and stimulate behavioural changes associated with '''broodiness and incubation'''. | ||
* '''Prolactin''' stimulates the production of '''crop milk''' in male and female columbiformes. | * '''Prolactin''' stimulates the production of '''crop milk''' in male and female columbiformes. | ||
* '''Oviposition''' is controlled by '''prostaglandins and Arginine Vasotocin'''. | * '''Oviposition''' is controlled by '''prostaglandins and Arginine Vasotocin'''. | ||
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== Ovulation== | == Ovulation== | ||
* Number of ovulations varies with species, mostly lay one clutch a year. | * Number of ovulations varies with species, mostly lay one clutch a year. | ||
| − | * [[ | + | * [[Avian Female Reproductive System#Infundibulum|Infundibulum]] catches the [[Oogenesis - Anatomy & Physiology|oocyte]], facillitated by the left abdominal air sac which tightly encloses the [[Avian Female Reproductive System#Ovary|ovary]]. |
| − | * Once ovulation has taken place, the [[ | + | * Once ovulation has taken place, the [[Follicles - Anatomy & Physiology|follicle]] shrinks and regresses. |
| − | * '''No [[ | + | * '''No [[Corpus Luteum - Anatomy & Physiology|corpus luteum]]''' remains, as there is no developing embryo to maintain. |
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== Oviposition == | == Oviposition == | ||
* Expulsion of the egg | * Expulsion of the egg | ||
| − | * Contraction of the [[ | + | * Contraction of the [[Avian Female Reproductive System#Vagina|Uterine shell gland (Vagina)]] with relaxation of abdominal muscles. |
* Minutes to hours | * Minutes to hours | ||
** Cuckoos lay their eggs in seconds so they can get away before the host returns. | ** Cuckoos lay their eggs in seconds so they can get away before the host returns. | ||
| + | == Post-Lay == | ||
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| + | * Enters a non-breeding state whilst incubating and caring for the brood. | ||
| + | * Resting ovary appears shrunken, similar to the juvenile [[Avian Female Reproductive System#Ovary|ovary]]. | ||
| + | * [[Avian Female Reproductive System#Oviduct|Oviduct]] regresses into an inconspicous, narrow tube. | ||
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| − | + | [[Category:Avian Reproduction]] | |
| − | + | [[Category:Bullet Points]] | |
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Latest revision as of 14:03, 5 July 2012
Breeding Cycles
- Classified according to length of cycle and the time of year when the species becomes reproductively active.
- Continuous breeders are reproductively active throughout the year e.g. Khaki Campbell duck.
- Most wild species that breed in temperate, subarctic and arctic zones display yearly cycles.
- Tropical or desert species may breed with cycles less than a year, at 6-month intervals or when conditions are favourable (opportunistic breeders).
- Usually lay one or more eggs in a clutch and terminate laying to incubate the eggs.
- Number of eggs per clutch and total number of clutches vary with species and season.
Endocrine Control
- In females, FSH is mainly responsible for follicular growth.
- Developing follicles produce Oestrogen from Theca and interstitial cells and Progesterone from Granulosa cells.
- Increasing levels of Oestrogen stimulate an LH surge to cause the follicle to split and release the primary oocyte.
- Oestrogen mobilizes calcium from the bone, increasing plasma concentrations for egg formation.
- Progesterone secretion continues to inhibit further ovulation and stimulate behavioural changes associated with broodiness and incubation.
- Prolactin stimulates the production of crop milk in male and female columbiformes.
- Oviposition is controlled by prostaglandins and Arginine Vasotocin.
Ovulation
- Number of ovulations varies with species, mostly lay one clutch a year.
- Infundibulum catches the oocyte, facillitated by the left abdominal air sac which tightly encloses the ovary.
- Once ovulation has taken place, the follicle shrinks and regresses.
- No corpus luteum remains, as there is no developing embryo to maintain.
Oviposition
- Expulsion of the egg
- Contraction of the Uterine shell gland (Vagina) with relaxation of abdominal muscles.
- Minutes to hours
- Cuckoos lay their eggs in seconds so they can get away before the host returns.