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− | <big><center>[[Reproductive System|'''BACK TO REPRODUCTIVE SYSTEM''']]</center></big>
| + | ==Male == |
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− | <big><center>[[Reproductive_System#Small_Domestic_Mammals|'''BACK TO SMALL DOMESTIC MAMMALS''']]</center></big>
| + | ===Penis === |
| | | |
| + | * Penis is easily extruded from the prepuce. |
| + | * Os penis lies within the tissue of the penis. |
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| + | === Testes === |
| | | |
| + | * Two testes in an external scrotum. |
| + | * Testes descend between day 30-40. |
| + | * Open inguinal canals throughout life. |
| + | ** Allows the testes to shrink and return to the abdomen during the non-breeding season. |
| + | * Head and tail of the epididymis are the sites of extremely large fat pads. |
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− | == Male == | + | === Accessory Sex Glands === |
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| + | Rats have highly developed accessory sex glands. These produce a gelatinous copulatory plug, which is visible in the vagina post-mating and is thought to prevent semen leaking out. |
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| + | |
| + | ==== Seminal Vesicles ==== |
| + | |
| + | * Lie dorsolateral to the urinary bladder in contact with the rectum dorsally. |
| + | * Large and lobated, opening into the lower end of the ductus deferens. |
| + | * Each is enclosed in a capsule together with the coagulating gland. |
| + | |
| + | ==== Prostate Gland ==== |
| + | |
| + | * Bilateral and has three lobes: the dorsal, lateral and ventral. |
| + | * Dorsal is known as the '''Coagulating Gland'''. |
| + | * Lies close to the seminal vesicle. |
| + | |
| + | ==== Ampullary Glands ==== |
| + | |
| + | * The glands of the ductus deferens. |
| + | * Lie near the bladder. |
| + | |
| + | ==== Bulbourethral Glands ==== |
| + | |
| + | * Found near the urethra as it exits the pelvis. |
| + | |
| + | ==== Preputial Glands ==== |
| + | |
| + | * Lie in the subcutaneous fat near the penis and open into the prepuce. |
| + | * Sebacious glands that secrete a [[Attractivity Behaviour - Anatomy & Physiology#Pheromones|pheromone]] used for scent marking. |
| + | * Regress with age and fill with stagnant [[Skin_- Anatomy & Physiology#Glands|sebum]]. |
| + | |
| + | === Puberty and Sexual Maturity === |
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| * Sexually mature at 6-8 weeks | | * Sexually mature at 6-8 weeks |
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− | ----
| + | === Mammary Gland === |
| + | |
| + | * Teats are absent. |
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| == Female == | | == Female == |
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− | * Bicornate uterus | + | === Reproductive tract === |
− | ** Short uterine body | + | |
− | ** Single [[Female_Reproductive_Tract_-The_Cervix_-_Anatomy_%26_Physiology|cervix]] | + | ==== Ovary ==== |
| + | |
| + | * Right [[Ovary - Anatomy & Physiology|ovary]] is located at the level of L4-5 just caudal to the right [[Renal Anatomy - Anatomy & Physiology#Common Anatomy|kidney]]. |
| + | * Left [[Ovary - Anatomy & Physiology|ovary]] is located at the level of L5-6 caudal to the left [[Renal Anatomy - Anatomy & Physiology#Common Anatomy|kidney]]. |
| + | ** Nearer the midline than the right [[Ovary - Anatomy & Physiology|ovary]]. |
| + | * Both [[Ovary - Anatomy & Physiology|ovaries]] are embedded in fat. |
| + | |
| + | ==== Oviduct ==== |
| + | |
| + | * [[Oviduct - Anatomy & Physiology|Oviduct]] is convoluted and winds around the [[Ovary - Anatomy & Physiology|ovary]] in 10-12 loops. |
| + | |
| + | ==== Uterus ==== |
| | | |
| + | * [[Uterus - Anatomy & Physiology#Anatomical_Types_of_Uteri|Duplex Uterus]] |
| + | ** Two [[Cervix - Anatomy & Physiology|cervices]] |
| + | ** Uterine horns remain separate until uniting in a single [[Vagina and Vestibule - Anatomy & Physiology|vagina]]. |
| + | |
| + | ==== Vagina ==== |
| + | |
| + | * Vaginal opening lies caudal to clitoral glands and is closed by a membrane until puberty. |
| + | ** '''Clitoral (Preputial) Glands''': Lie in subcutaneous fat near the clitoris and open into a preputial fold. |
| + | *** Sebacious glands that secrete a [[Attractivity Behaviour - Anatomy & Physiology#Pheromones|pheromone]] used for scent marking. |
| + | |
| + | ==== Attachments and Blood Supply ==== |
| + | |
| + | * Anastamoses between the ovarian and uterine artery occur in the uterine mesentery. |
| + | * Mesovarium and mesometrium contain large volumes of fat, which surround the [[Renal Anatomy - Anatomy & Physiology#Common Anatomy|kidneys]], abdominal wall and [[Alimentary_- Anatomy & Physiology|intestinal loops]]. |
| + | |
| + | ===Oestrous Cyclicity === |
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| * Non-seasonal polyoestrus | | * Non-seasonal polyoestrus |
− | * Oestrus cycle 4-5 days. | + | * LH surge (responsible for [[Ovulation - Anatomy & Physiology|ovulation]]) is strongly linked to circadian rhythm and usually occurs in the late afternoon. |
| + | * [[Oestrous Cycle - Anatomy & Physiology|Oestrus cycle]] 4-5 days. |
| * Duration of oestrus is ~14 hours. | | * Duration of oestrus is ~14 hours. |
| | | |
| + | === Gestation and Offspring === |
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− | * Ejaculate plug forms in the vagina.
| + | ==== Gestation ==== |
− | | |
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| * Gestation length is 20-22 days. | | * Gestation length is 20-22 days. |
| + | * [[Placenta - Anatomy & Physiology|Placenta]] is haemochorial. |
| | | |
| + | ==== Litter ==== |
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− | * litter size 6-16 | + | * Litter size 6-16 |
| * Altricial young | | * Altricial young |
| ** Eyes open at 12-14 days. | | ** Eyes open at 12-14 days. |
| * Earliest weaning age 21 days. | | * Earliest weaning age 21 days. |
| * Care not to stress mother or she may cannibalise the young. | | * Care not to stress mother or she may cannibalise the young. |
| + | |
| + | === Mammary Gland and Lactation === |
| + | |
| + | * The rat has 6 pairs of mammary glands. |
| + | * Thoracic and inguinal glands act as two discrete complexes, separated by a space just behind the ribs. |
| + | ** During lactation, the thoracic glands expand rostrally as far as the [[Salivary_Glands_-_Anatomy_&_Physiology#Major_Salivary_Glands|parotid and mandibular glands]]. |
| + | *** Cranially and medially over the upper forelimb and along the lateral thoracic wall. |
| + | ** Inguinal gland covers the lateral abdominal wall back to the stifle and anal region. |
| + | * At the base of each teat the transition zone between hairless and hair has large sebacious glands. |
| + | |
| + | ==== Cervical gland ==== |
| + | |
| + | * Rudimentary |
| + | |
| + | ==== Thoracic gland ==== |
| + | |
| + | * Diffuse. |
| + | * Contains 3 nipples |
| + | * Surrounds the base of the forelimb. |
| + | |
| + | ==== Abdominal gland ==== |
| + | |
| + | * Only marginally developed. |
| + | |
| + | ==== Inguinal gland ==== |
| + | |
| + | * Surrounds the base of the hindlimb. |
| + | * Contains 3 nipples. |
| + | |
| + | |
| + | [[Category:Small Mammal Reproduction]][[Category:Bullet Points]] |