Both men and women have nipples and mammary glands, but usually only women have them develop at puberty.

男性和女性都有乳头和乳腺，但通常只有女性才会在青春期发育。

These lactotrophs secrete the hormone prolactin, and the increased levels of prolactin prepares the mammary glands to produce milk.

泌乳细胞分泌催乳素，而催乳素水平的增高使得乳腺可以产生乳汁。

And at some point, synapsids even evolved mammary glands, when they were still laying eggs.

在某些时候，突触甚至在它们还在产卵的时候就进化出了乳腺。

Using electricity, they transferred the mammary gland cell's nucleus into an egg cell from a second sheep.

们利用电将乳腺细胞的细胞核转移到第二只绵的卵细胞。

Like fur, this one's harder to see in the fossil record - we don't have any fossilized mammary glands.

像毛皮一样，这在化石更难见到——我们没有任何乳腺化石。

Mammary glands eventually secrete the milk through the breasts, udders, or, in the rare case of the platypus, through ducts in the abdomen.

乳腺最终通过乳房、乳房分泌乳汁，或者在鸭嘴兽的罕见情况下， 通过腹部导管分泌乳汁。

Oxytocin causes cells that line the mammary glands to contract and is also known as the cuddle hormone, as it enhances the bonding experience between mother and child.

催产素促进排列乳腺的细胞收缩，也被称为拥抱激素，因为它增强了母亲和孩子之间的联结体验。

It is admitted by most evolutionists that mammals are descended from a marsupial form; and if so, the mammary glands will have been at first developed within the marsupial sack.

大多数进化论者都承认哺乳动物是有袋类动物的后代；如果是这样， 那么乳腺将首先在有袋动物的袋内发育。

Her very entry to the world was groundbreaking – she was cloned using cells taken from another sheep's mammary gland as part of an experiment conducted by the Roslin Institute in Midlothian, Scotland.

她进入这个世界是开创性的——她是使用从另一只绵乳腺提取的细胞进行克隆的， 这是苏格兰洛锡安的罗斯林研究所进行的一项实验的一部分。

The development of the mammary glands would have been of no service, and could not have been affected through natural selection, unless the young at the same time were able to partake of the secretion.

乳腺的发育将毫无用处， 也不会受到自然选择的影响，除非同时期的幼崽能够分享乳腺的分泌物。

The calcium is in the soil, it goes up into the plant, the cow gets hungry, it eats the plant, the calcium goes to the bloodstream, through the mammary glands and squirts out as milk.

钙在土壤，它进入植物，母牛饿了，它吃植物，钙进入血液，通过乳腺并以牛奶的形式喷出。

The mammary glands are common to the whole class of mammals, and are indispensable for their existence; they must, therefore, have been developed at an extremely remote period, and we can know nothing positively about their manner of development.

乳腺是所有哺乳动物共有的， 是它们生存所不可或缺的；因此，它们一定是在极其遥远的时期发展起来的， 我们对它们的发展方式一无所知。