Monday, July 13, 2009

Artificial reproduction through stem cells

Stem cell are the buildings blocks of our body. They make up the cells in our body in which makes up our blood nerves or even brain. Therefore, it leads to the possibility of producing male cells in humans.
Sperms grown from a mouse's cell proved successful in fertilizing it's females eggs and produce offspring. Even so, scientists have been able to turn male embryonic stem cells into sperms by treating it with a varitey of substances which turned the embryonic stem cells into germline stem cells, which then turned into primitive male stem cells. The primitive stem cells then splitted in which matured into sperms.
However, the possibility of producing a male sperm from a female stem cell is still beyond our technological reach due to its biological barriers. Thereby, it leads to a possiblity of doing so in future.

Stem cells

There are mainly two kinds of stem cells, embryonic and adult. Embryonic stem cells are able to grow into various kinds of specialized tissues of an embryo. Adult stem cells howeve, are able repair parts of our body and sustain organs which continually produce our blood and skin.
Stem cells have this amazing capability of growing into different kinds of cells through cell culture and also continually renew itself. Through mitotic cell division, it allows them to be grown into many types of cells, spurring speculation of producing male sperms from a female.

Friday, July 10, 2009

Natural reproduction in single-sex environment

Besides asexual reproduction, there is another type of reproduction similar to it, however, it requires fertilization.
Known as "protogyny" meaning the change of gender, a species of fish called "wrassess" are able to do so. Their female can morph into "intial phase" males or "terminal phase" males. When any of their males leave the group or die out, these females will morph into males and take their place.
In some other species of fish called the "parrotfish", they are also able to change gender. As they start maturing, hormones are released, changing them into male or female due to chemical signals. They are borne as either males of females, and when there comes a need to replace a male or a female, they would change gender as they mature.
In some species of frogs, this also happens. Chemical signals which detect the number of its own kind act accordingly, changing their set of reproductive organs from male to female, or vice-versa.
Through genetic engineering, humans might be able to obtain this wonderful evolutionary measure, in the future!

How does asexual reproduction in animals occur?

Animals such as starfish of sea anemones reproduce through asexual reproduction. They give birth asexually through a process known as "mitosis"(nuclear division).
There are different phases of mitosis, which, according to chronological order are: interphase, prophase, prometaphase, metaphase, anaphase, telophase, cytokenesis.
During the interphase stage, DNA from the parent cell is replicated, centrioles(microtubules) and proteins for the development of the cells are produced.
During the prophase stage, The parent DNA and proteins and then codensed into chromosomes.
During the prometaphase stage, the nucleus disappears, the centrioles reach for the poles of the cell, and the chromosomes contract.
During metaphase, chromosomes are aligned at the center of the cell by spindle fibres located from two poles of the cell.
During anaphase, the fibres shorten and the chromsomes are gradually pulled apart.
During telophase, the chromosomes reach the poles and the spindle fibres vanishes.
Finally, at cytokenesis, the cell is split into two.
This proccess will then be repeated over and over again until it's offspring is formed. Perhaps when we are more teachnologically advanced in future, we are able to extract this trait and gnetically modify it for our own.

Natural reproduction in humans

Before i start my research, it would be crucial that we know the basics of human life- natural reproduction.
Firstly, it requires the interactions between the male penis and the female vagina. the male testes produces sperm which is needed for the fertilization of the female egg. The female ovaries in turn, produce the eggs(ovum), which travels through the fallopian tubes and into the uterus, to be fertilized by the male sperm.
During sexual intercouse, the male would ejaculate semen which contains an average 50-130million spemrs per ml into the female vagina. The sperms would swim through the vagina and cervix, and into the uterus or fallopian tubes where only one sperm will fertilize the ovum.
After fertilization, gestation, or the development of the baby begins.
However, what we need to know is for the possibility of a birth in an all woman society. Thus, this shall be the marking point of my research.