COMPARISON OF THE MODE OF REPRODUCTION BETWEEN PLACENTAL MAMMALS AND MARSUPIALS

Marsupial and placental mammals have the main difference between them which is their ''rate of gestation'' (Wikipedia contributors, 2006). Both the marsupials and the placental mammals are also different when coming to the pattern and the reproductive anatomy. The mode of reproduction is also said to be more complex in marsupials as compared with the mode of reproduction in the placental mammals which is not complex. Placental mammals are vertebrates while on the other side placental mammals are invertebrates.

It is also said in the introductory paragraph that the mode of reproduction in both the marsupials and the placental mammals is totally different. In marsupials, it is said that the reproductive tracts are fully doubled. There is no fusion in both the left and the right varginae of the marsupials in order to form the single body as they occur in all placental mammals. Marsupials also give birth through a ''new median canal which is known as the pseudovaginal canal'' (Wund and Myers, 2006). Both the right uterus and the left uterus are not fused in marsupials as opposed to the placental mammals; where fusion of both the right and the left uteri do occur differently.

In the embryo of the marsupials which is still in the process of the development, ''female reproductive tract which is formed as the result of the arrangement of ducts is also totally different with the one which is found in the placental mammals'' (Wund and Myers, 2006: 1). Still in marsupials, marsupium or pouch develops in the females in order to nurse the young once. The penis in the male marsupials is doubled like in the female marsupials. In placental mammals, the scrotum is found in the posterior end of the penis, unlike in the marsupials where the scrotium is found in the anterior part of the penis.

It is also said that gestation also differs between the two species, marsupials and the placental mammals. In marsupials both short and long gestation does occur as opposed to the placental mammals. The occurrence of the short gestation is attributed to the development of the york in the type of reproduction. While on the other side the longer gestation in marsupials is attributed to the offspring which are born well fully developed. The rate of birth between marsupials and the placental mammals also takes place differently. In marsupials, birth takes place early as compared with the placental mammals where birth takes place late. Furthermore, an important difference also do occur between the two species, marsupials and the placental mammals in their mode of reproduction. Wund and Myers (2006: 2) further say that pregnancy in placental mammals interrupts the development of the oestrus cycle as opposed to pregnancy which does not interrupt the development of the oestrus cycle.

In conclusion, one can say that there is a huge different between the marsupials and placental mammals, when coming to the comparison of their mode of reproduction. The huge difference can also attribute to the fact that the two species are totally different. Marsupials are not vertebrates while placental mammals are thought to be invertebrates. Gestation period in both species is also different. Marsupials have both short and long period when coming to gestation as opposed to the placental mammals.

References:

Wikipedia contributors. Placenta [Internet]. Wikipedia, The Free Encyclopedia; 2006 May 07, 18:21 UTC [cited 2006 May 11, 15:31]. Available from: http://en.wikipedia.org/wiki/Placenta

Wikipedia contributors. Marsupials [Internet]. Wikipedia, The Free Encyclopedia; 2006 May 09, 17:16 UTC [cited 2006 May 11, 15:12]. Available from: http://en.wikipedia.org/wiki/Placenta

Wund, M. and Myers, P. 2006. Animal Diversity Web. [Onlike]. Available from: http://animaldiversity.ummz.umich.edu/site/accounts/information/Metatheria.html


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