The marsupial animals belong to the Marsupial order; they share the infraclass metatheria with the kangaroo, koala, Tasmanian devil and the Virginia opossum. They are the non placental mammals, the female marsupials carriers her young in a pouch. The Concise Oxford Dictionary describe pouch, as a ‘pocket-like abdominal receptacle in which marsupials carry their young during lactation’.
The placenta mammals are named because of its function; it connects the growing embryo within the uterus to the circulatory system of their mother. The placenta is the pathway provider for the nourishment of the fetus. Most of the placenta mammals are investing most of their time in the stage of growth.
The main difference between the marsupial and placental mammals is the rate of gestation, or the time the offspring take inside the uterus. The Concise Oxford Dictionary explains gestation as the process of carrying or being carried in the womb between conception and birth. The stage of mating happens throughout the year in the marsupial mammals than in any other species. The marsupial females use the amniotic membrane to separate the developing embryo from their body. The functions of the amniotic membrane is to protect the embryo, it protect it by isolating it from all biological interactions with the parent. The amniotic membrane play important role, because when fertilization took place the embryo becomes a new organisms and the immune systems attack it, but because of the protection the attacker becomes unsuccessful.
The fewer the nutrients in the egg will result in the few nutrients of marsupial embryo, because they depends on the egg yolk for their nutrients. The type of egg yolk reproduced determines the period of gestation in marsupials. The marsupials give births very fast, the longest period they can spend in a reproduction are only twelve days. On the other side, the placental mammals takes weeks and months which is longer compared to the marsupials mammals.
The placental mammals have a long gestation period because their offspring is born being well developed. The placenta allows the nutrients to travel from the mother systems to the embryo and waste are carried out, and this allows the extension of placental maturation. The placenta is composed of numerous layers of blood supply; the mother and embryo have their own blood supply.
In conclusion, indeed there are difference mode of reproduction between the placental and the marsupial. During pregnancy of the marsupials the oestrus cycle occur, while in the placental does not until the whole period of pregnancy is over. The embryo of the marsupial is not connected to the mother while of the placental is connected. The marsupial gives birth very fast as compared to the placental. The main difference between the marsupial and placental mammals is the rate of gestation, or the time the offspring take inside the uterus.
1. [http://nwcreation.net/marsupials.html, accessed on 12/05/2006, 08:00].
2. Wikipedia contributors. Placenta. The free Encyclopedia [internet], 2006 May 12, 09:00. PTA. Available from [http://en.wikipedia.org//wiki/placenta].
3. Wikipedia contributors. Marsupials. The free Encyclopedia [internet], 2005 May 12, 10:30 PTA [Cited 2006 may 11] Available from [http://en.wikipedia.org//wiki/placenta