點解眼珠會綠色?

我們見到眼珠顏色實為虹膜，為何眼珠為綠色請見####

我們眼睛裡的虹膜(iris)所含的色素可以決定眼睛的顏色，不同人種的人基因上不太相同,
所以!色素不一樣~眼睛顏色不太一樣阿.

虹膜為一個圓形薄膜，懸在房水之中，位於月膜後的海綿組織內。虹膜內含色素細胞（此為控制瞳孔顏色的要素）、肌纖維、血管和神經。虹膜正中央圓心處，為瞳孔的所在。當光線經角膜而進入瞳孔後，虹膜就依光量的大小進行調節。當強光射入時，在瞳孔四周的平滑肌（又名瞳孔括約肌）會受到刺激，並藉由副交感神經的支配，使瞳孔縮小。

####虹膜顏色會因為人種的不同而深淺不一，而在東方人一般均為深棕色，若有顏色異常必須懷疑是一些全身性的疾病；像惡性貧血、銅代謝等。

決定眼珠顏色的是虹膜組織裡所含有色素的量。而虹膜就是角膜後面瞳孔外圍的一層環狀薄膜，而瞳孔正是這層薄膜中央的一個圓孔。在虹膜組織裡，含有兩種不同的棕色色素：１．虹膜後面有一層排列得非常整齊的上皮細胞，這裡的色素不僅顆粒大，顏色深，而且排列緊密，一絲一毫光線也不可能由此通過，這層色素細胞永遠不變。２．另一種色素顆粒細，顏色淡，分散在虹膜淺層及其表面，這種色素隨著年齡的增長而增多，愈到年老愈豐富。而人在非常幼小的時候，虹膜前層沒有色素，虹膜深處的濃密色素，經過很厚的前層組織透露出來，就變為黑色的了。人到中年以後，色素逐漸增加，虹膜的顏色也由黑轉棕，到老年，你所看到的虹膜顏色，全是以後沉積在虹膜層的細碎色素。而虹膜後層又濃又密的色素，反而被這層細碎的色素所掩蓋，看不見了，這種細碎的色素顏色很淡，所以老年人的虹膜就變為黃色了。

虹膜的顏色可以是褐色和藍色，歐美人士大多擁有藍色的，亞洲則是褐色的。####原來有一對因子控制虹膜有沒有顏色，（若果沒有，虹膜就變成綠）另外一對因子控制虹膜的顏色。某人若是擁有兩個使人有褐色虹膜的因子，那人就必然是褐色眼睛的，（因為沒有使人有藍色虹膜的因子）；某人若是擁有兩個使人有藍色虹膜的因子，那人就必然是藍色眼睛的，（因為沒有使人有褐色虹膜的因子）。問題又來了。如果某人擁有一個使人有藍色虹膜的因子，　及一個使人有褐色虹膜的因子，那麼，由於使人有藍色虹膜的因子是隱性，使人有褐色虹膜的因子是顯性，那人都會有一雙褐色的眼睛的。基本上它是取決於DNA的差異而有不同~DNA跟遺傳有非常大的關係~因為我們跟外國人的DNA碼的差異~所以導致不僅是虹膜的部份~甚至是髮色~膚色~等等~都是受到DNA的差異影響喔~ 紅眼珠、藍眼珠都是月亮的孩子

This is the matter of genetics. The allele for green eyes is recessive(make is be "ee"). The allele for brown eyes is dominant("EE"). According to the genetics, the dominant allele will supress the recessive allele. That means people have allele of "EE" or "Ee" will also have a brown eyes. Your parents both have the allele of "Ee". And your allele is come from your parents. Before your birth, your parents carry our fertilization, that means the combination of their sperm and eggs. The genetic materials in sperm and egg is produced by meiosis cell division. Therefore, there are genetic variation. As I told before your father have the allele of "Ee", his has two kinds of sperm, one kind of it contains the allele of E, and one kind of it contains the allele of "e". Your mother also have the allele of "Ee", so she also has two kinds of egg, one kind of it contains the allele of E, and one kind of it contains the allele of "e". As the sperm and egg is combined by chance, when the sperm carrying the "e" allele combine with the egg carrying the "e" allele, the allele in the embryo(you) become "ee". As there is no "E" in your allele, you will have a pair of green eyes instead of a pair of brown eyes. If you don't understand, you will study it later in your F.5.

2007-01-20 12:37:14 補充：
SORRY 出現亂碼, "). 解"

基本上係無問題的，是在呼眼睛的色素

有機會是︰
‧眼睛有病害
‧染色體病變
‧基因變異
‧遺傳性
‧有某種物質在內影響

1.是病變
2.是遺傳
3.染色體病變

你唔係講緊人啊~~~~~~?
好恐怖wo...........
i don't know that!!!!!!!!!
唔關我是===========