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Amphibian Reproduction - Anatomy & Physiology (view source)
Revision as of 15:21, 29 November 2010
, 15:21, 29 November 2010Text replace - "-_Anatomy_%26_Physiology" to "- Anatomy & Physiology"
* Both male and female must be present.
* Both male and female must be present.
* Both sperm and [[The_Ovary_-_Oocytes_-_Anatomy_%26_Physiology|oocyte]] contribute to the embryo.
* Both sperm and [[The_Ovary_-_Oocytes_- Anatomy & Physiology|oocyte]] contribute to the embryo.
== Gynogenesis ==
== Gynogenesis ==
* 99% female contribution.
* 99% female contribution.
* Mitosis occurs without separation and meiosis follows.
* Mitosis occurs without separation and meiosis follows.
* Sperm nucleus does not enter the [[The_Ovary_-_Oocytes_-_Anatomy_%26_Physiology|oocyte]] to form the diploid state.
* Sperm nucleus does not enter the [[The_Ovary_-_Oocytes_- Anatomy & Physiology|oocyte]] to form the diploid state.
** Sperm contributes no genetic material to the embryo.
** Sperm contributes no genetic material to the embryo.
* Sperm are only required to [[Fertilisation%2C_Implantation_and_Early_Embryonic_Development_-Fertilisation-_Anatomy_%26_Physiology#Syngamy|activate]] the embryo.
* Sperm are only required to [[Fertilisation%2C_Implantation_and_Early_Embryonic_Development_-Fertilisation- Anatomy & Physiology#Syngamy|activate]] the embryo.
== Parthenogenesis ==
== Parthenogenesis ==
* An asexual form of reproduction found in females where growth and development of embryos occurs without fertilization by males.
* An asexual form of reproduction found in females where growth and development of embryos occurs without fertilization by males.
* 100% female contribution.
* 100% female contribution.
* Self-activated [[The_Ovary_-_Oocytes_-_Anatomy_%26_Physiology|oocytes]] require no contribution from sperm.
* Self-activated [[The_Ovary_-_Oocytes_- Anatomy & Physiology|oocytes]] require no contribution from sperm.
* The offspring produced by parthenogenesis almost always are female in species where the XY chromosome system determines gender.
* The offspring produced by parthenogenesis almost always are female in species where the XY chromosome system determines gender.
=== Ovaries ===
=== Ovaries ===
* Produce 1-25,000 [[The_Ovary_-_Oocytes_-_Anatomy_%26_Physiology|oocytes]] at a time.
* Produce 1-25,000 [[The_Ovary_-_Oocytes_- Anatomy & Physiology|oocytes]] at a time.
* Under the influence of the [[Pituitary_Gland_-_Anatomy_%26_Physiology|pituitary gland]].
* Under the influence of the [[Pituitary_Gland_- Anatomy & Physiology|pituitary gland]].
* [[The_Ovary_-_Oocytes_-_Anatomy_%26_Physiology|Oocytes]] squeeze out into the [[Peritoneal_Cavity_-_Anatomy_%26_Physiology|peritoneal cavity (ceolom)]].
* [[The_Ovary_-_Oocytes_- Anatomy & Physiology|Oocytes]] squeeze out into the [[Peritoneal_Cavity_- Anatomy & Physiology|peritoneal cavity (ceolom)]].
* Cilia in the ceolom direct the ova into the infundibulum of the oviduct.
* Cilia in the ceolom direct the ova into the infundibulum of the oviduct.
* The oviduct (Mullarian Duct) covers the egg with a jelly-like material.
* The oviduct (Mullarian Duct) covers the egg with a jelly-like material.
* Oviduct and utreter may be united through much of their length.
* Oviduct and utreter may be united through much of their length.
* Open into the [[Exotics_-_Amphibian_Reproductive_Anatomy_and_Physiology_-_Anatomy_%26_Physiology#Cloaca|cloaca]].
* Open into the [[Exotics_-_Amphibian_Reproductive_Anatomy_and_Physiology_- Anatomy & Physiology#Cloaca|cloaca]].
=== Testes ===
=== Testes ===
* Located near the [[Urinary System - Anatomy & Physiology|kidneys]].
* Located near the [[Urinary System - Anatomy & Physiology|kidneys]].
* Produce sperm under the influence of the [[Pituitary_Gland_-_Anatomy_%26_Physiology|pituitary gland]].
* Produce sperm under the influence of the [[Pituitary_Gland_- Anatomy & Physiology|pituitary gland]].
* Often a rudimentary [[Female_Reproductive_Tract_-The_Ovary_-_Anatomy_%26_Physiology|ovary]] (known as the Bidder's organ)nearby in the male.
* Often a rudimentary [[Female_Reproductive_Tract_-The_Ovary_- Anatomy & Physiology|ovary]] (known as the Bidder's organ)nearby in the male.
==== Bidder's Organ ====
==== Bidder's Organ ====
* The organ is located just in front of the [[Urinary System - Anatomy & Physiology|kidney]] (mesonephros).
* The organ is located just in front of the [[Urinary System - Anatomy & Physiology|kidney]] (mesonephros).
* It is formed at the cranial tip of the male and female gonad during the larval stage.
* It is formed at the cranial tip of the male and female gonad during the larval stage.
* Normally it is inactive and contains miniature [[The_Ovary_-_Follicles_-_Anatomy_%26_Physiology|follicles]] which have the capability to mature (becoming active).
* Normally it is inactive and contains miniature [[The_Ovary_-_Follicles_- Anatomy & Physiology|follicles]] which have the capability to mature (becoming active).
* When the female population is scarce, the Bidder's organ enlarges and produces viable oocytes and then gonadotropins, which stimulate the growth of the Müllerian ducts to form uterus and oviducts.
* When the female population is scarce, the Bidder's organ enlarges and produces viable oocytes and then gonadotropins, which stimulate the growth of the Müllerian ducts to form uterus and oviducts.
* Its internal anatomy consists of two parts:
* Its internal anatomy consists of two parts:
** Central portion: consists of connective tissue and rich in blood vessels.
** Central portion: consists of connective tissue and rich in blood vessels.
** Periphery: consists of the cortex, which contains [[The_Ovary_-_Follicles_-_Anatomy_%26_Physiology|follicles]] in various stages of development.
** Periphery: consists of the cortex, which contains [[The_Ovary_-_Follicles_- Anatomy & Physiology|follicles]] in various stages of development.
** Molecules of various proteins are present in the outer layer of the [[The_Ovary_-_Follicles_-_Anatomy_%26_Physiology|follicles]], homologous to the zona pellucida of the ovum.
** Molecules of various proteins are present in the outer layer of the [[The_Ovary_-_Follicles_- Anatomy & Physiology|follicles]], homologous to the zona pellucida of the ovum.
=== Male Ducts ===
=== Male Ducts ===