受孕六周后你的孩子有你小手指甲那么大。

Six weeks after conception, your baby is the size of your little fingernail.

当一个精子和一个卵子结合时受孕就发生了。

Conception occurs when a single sperm fuses with an egg.

这种行为表明新鲜擦痕上的化学物质可能有助于从生理上诱导并让关注这些擦痕的雌鹿同时受孕。

In view of this behavior it has been suggested that chemicals present in fresh buck rubs may help physiologically induce and synchronize fertility in females that visit these rubs.

比如发情的雌马，尽管它会热情地撩拨和刺激公马，但在那个精确时刻到来前——也就是卵子到达受孕位置之前，它绝不会让公马近身。

With horses for example, the female on heat teases and excites the male but won't let him mount until the exact second when the egg is in the right position for fertilisation.