UTERUS.pptx

uterus of mammals

1. Uterus and its modification in mammals

2. Uterus Uterus is an inverted pear shaped organ of female reproductive sytem. It is a hollow cavity of female mammals in which the fertilized e ggs implant and develops. It is situated between the fallopian tube and the vagina. It is also known as womb. Ref. www.britannica.com

3. Structure of the Uterus It is 2.5 to 3.0 inches long and about 2.0 to 2.5 inches across at the top. The Fallopian tube enters the uterus from the top and the cervix extends down the vagina. Oviduct serve as passageways for ova to reach uterus. It is lined by the endometrium . Ref. – Man & Vertebrates by Romer

4. Anatomy of Uterus From outside to inside the path of the uterus is as follows: Vagina :Vagina are soft ,distancible, cornified and also grandular in some of the animals. Vagina joins posteriorly by excretory duct u rethra to form a common urogenital cavity, the vestibule. It is absent in monotremes. In marsupials vagina is a double organ. In placental mammals a single vagina is present .

5. B:Cervix Uteri(Neck of the Uterus) It is situated at the neck to the vagina called the neck of uterus. It is divisible into the following three categories: 1:External orifice of uterus. 2:Canal of the cervix 3:Internal orifice of uterus. C : Corpus uteri It is known as body of uterus Made up of: 1:Cavity of body of uterus 2: Fundus

6. Histology 1: Endometrium : Lining of the uterine cavity is called endometrium. In most of the mammals including humas the endometrium builts a lining periodially which if no pregnancy occurs is shed or reabsorbed. 2:Myometrium . Uterus consists of a smooth muscle known as myometrium. The inner most layer of the myometrium is known as junction zone. 3:Perimetrium It is a loose connective tissue around the uterus. 4:Peritoneum . Uterus is surrounded by the peritoneum.

7. Position of Uterus Under normal conditions , the uterus is antiflux and antiverted . Sometimes is also found in retroverted or retroflexed condition . It is lined by following ligaments: 1-Anterior ligament 2-Posterior l igamnet 3-Lateral ligament 4-Uterosacral ligament 5-Round ligament 6-Ovarian ligament Ref. – www.britannica.com

8. Modification of Uterus 1-Duplex Uterus It is the most primitive type found in Eutherian mammals. For example: Lagomorpha . In this type , there are two separate uteri i.e., completely double uterus with two cervices, hence known as duplex uterus. Uteri opens into the vagina via two openings known as os-uteri. In montremes , the genital tract is without vagina . For example : Ornithorhynchus In marsupials, dupex uterus and dupex vagina is found. In placental mammals, the oviduct unites to form single vagina. For example : E lephant . Ref. – A Textbook of Zoology by Parker & Haswell

9. Bipartite Uterus Here, the uterus is “Y” shaped externally. There is beginning of fusion between two uteri Examples : Carnivores, pigs,some ungulates . It is also found in some ungulates. Ref Life of Vertebrates by Young

10. Bicornuate Uterus These are found in sheep , whales , bats . Here, the uterus consist of an enlarged posterior cavity with two uterine horns leading into it. In this type , a larger portion of oviduct functions as uterus.

11. Simplex Uterus It is characteristic of primates including man. There is fusion of uterus complete to the mullerian duct i.e., – uterus and vagina become completely fused. There is a single uterine cavity. Placenta consists of villi of uterine wall.

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