【英语时差8,16】背后的蓝色胎记
时间：2018-12-03 作者：英语课 分类：英语时差8，16
英语课
Parents of East Asian, East African and Native American descent are not usually surprised when their babies are born with distinctive 1 blueish-gray or blueish-green birthmarks on their backside.
Eighty to ninety-five percent of infants from these ethnicities bear the marks, and they are also quite common on Hispanic babies. The spots appear at the base of a baby's spine 2 at birth or a few weeks afterwards, and usually fade after a few years.
The birthmark is often called a "Mongol Spot" because in ancient times the trait was characteristic in Mongolian tribes. But as the Mongols merged 3 with other populations, the trait became less pervasive 4, and in some populations it is now undetectable.
Although uncommon 5 in Caucasian and other groups, a similar spot can be seen microscopically 6 in all newborns regardless of race. The birthmark is produced in a deep layer of the skin by a large cluster of melanocytes--or pigment 7 cells--formed from precursor 8 cells that migrated into the skin during embryonic 9 development.
Sometimes the birthmarks are confused with bruises 11 because the light scattering 12 effect responsible for making a bruise 10 look blue is the same reason why Mongol Spots look blue. The pigment for Mongol Spots is deep within the skin, so longer-waved light-- which appears as the color red--is absorbed. And shorter-waved light--that appears as blue--is reflected back to our eyes.
Some cultures believe the spots are left from where the baby was prodded 13 or slapped by a spirit to leave "pre-life" and be born, others say it's a sign of royalty 14. In truth, they are congenital birthmarks.
Eighty to ninety-five percent of infants from these ethnicities bear the marks, and they are also quite common on Hispanic babies. The spots appear at the base of a baby's spine 2 at birth or a few weeks afterwards, and usually fade after a few years.
The birthmark is often called a "Mongol Spot" because in ancient times the trait was characteristic in Mongolian tribes. But as the Mongols merged 3 with other populations, the trait became less pervasive 4, and in some populations it is now undetectable.
Although uncommon 5 in Caucasian and other groups, a similar spot can be seen microscopically 6 in all newborns regardless of race. The birthmark is produced in a deep layer of the skin by a large cluster of melanocytes--or pigment 7 cells--formed from precursor 8 cells that migrated into the skin during embryonic 9 development.
Sometimes the birthmarks are confused with bruises 11 because the light scattering 12 effect responsible for making a bruise 10 look blue is the same reason why Mongol Spots look blue. The pigment for Mongol Spots is deep within the skin, so longer-waved light-- which appears as the color red--is absorbed. And shorter-waved light--that appears as blue--is reflected back to our eyes.
Some cultures believe the spots are left from where the baby was prodded 13 or slapped by a spirit to leave "pre-life" and be born, others say it's a sign of royalty 14. In truth, they are congenital birthmarks.
1 distinctive
adj.特别的，有特色的，与众不同的
- She has a very distinctive way of walking.她走路的样子与别人很不相同。
- This bird has several distinctive features.这个鸟具有几种突出的特征。
2 spine
n.脊柱，脊椎；(动植物的)刺；书脊
- He broke his spine in a fall from a horse.他从马上跌下摔断了脊梁骨。
- His spine developed a slight curve.他的脊柱有点弯曲。
3 merged
（使）混合( merge的过去式和过去分词 )； 相融； 融入； 渐渐消失在某物中
- Turf wars are inevitable when two departments are merged. 两个部门合并时总免不了争争权限。
- The small shops were merged into a large market. 那些小商店合并成为一个大商场。
4 pervasive
adj.普遍的；遍布的，(到处)弥漫的；渗透性的
- It is the most pervasive compound on earth.它是地球上最普遍的化合物。
- The adverse health effects of car exhaust are pervasive and difficult to measure.汽车尾气对人类健康所构成的有害影响是普遍的，并且难以估算。
5 uncommon
adj.罕见的，非凡的，不平常的
- Such attitudes were not at all uncommon thirty years ago.这些看法在30年前很常见。
- Phil has uncommon intelligence.菲尔智力超群。
6 microscopically
显微镜下
- Microscopically the ores are medium grained to amorphous. 显微镜下，矿石为中粒至非晶质。 来自辞典例句
- He studied microscopically the statistics of trade. 他极仔细地研究了贸易统计数字。 来自辞典例句
7 pigment
n.天然色素，干粉颜料
- The Romans used natural pigments on their fabrics and walls.古罗马人在织物和墙壁上使用天然颜料。
- Who thought he might know what the skin pigment phenomenon meant.他自认为可能知道皮肤色素出现这种现象到底是怎么回事。
8 precursor
n.先驱者；前辈；前任；预兆；先兆
- Error is often the precursor of what is correct.错误常常是正确的先导。
- He said that the deal should not be seen as a precursor to a merger.他说该笔交易不应该被看作是合并的前兆。
9 embryonic
adj.胚胎的
- It is still in an embryonic stage.它还处于萌芽阶段。
- The plan,as yet,only exists in embryonic form.这个计划迄今为止还只是在酝酿之中。
10 bruise
n.青肿，挫伤；伤痕；vt.打青；挫伤
- The bruise was caused by a kick.这伤痕是脚踢的。
- Jack fell down yesterday and got a big bruise on his face.杰克昨天摔了一跤，脸上摔出老大一块淤斑。
11 bruises
n.瘀伤，伤痕，擦伤( bruise的名词复数 )
- He was covered with bruises after falling off his bicycle. 他从自行车上摔了下来，摔得浑身伤痕。 来自《简明英汉词典》
- The pear had bruises of dark spots. 这个梨子有碰伤的黑斑。 来自《简明英汉词典》
12 scattering
n.[物]散射；散乱，分散；在媒介质中的散播adj.散乱的；分散在不同范围的；广泛扩散的；（选票）数量分散的v.散射(scatter的ing形式)；散布；驱散
- The child felle into a rage and began scattering its toys about. 这孩子突发狂怒，把玩具扔得满地都是。 来自《简明英汉词典》
- The farmers are scattering seed. 农夫们在播种。 来自《简明英汉词典》