If you're at all like me, it's not enough to know that she's pregnant and then then sit back and wait for the delivery. I want to know what's happening throughout the whole process, especially cause the wonders of embryo/foetal development amaze me - it's a true miracle :)
The development is split into 3 stages : Pre-attachment, Embryonic and Foetal.
1. Pre-attachment
After fertilisation there are two nuclei in each egg, one from each parent carrying half of their chromosomes. When these fuse, the puppy is created carrying the full complement of 78 chromosomes (as opposed to humans with 46, sheep 54, horse 64 and a Kingfisher at 132 !). 8 to 9 days after fertilisation they travel down into the uterus.
2. Embryonic stage
Placentas start to develop about 17 days after fertilisation and at around day 20 the embryos (less than a half an inch long) begin to attach themselves to the walls of the uterus. The central nervous system is developed at this stage. Over the next week the brain and spinal cord develop along with the rest of the organs, limbs, head, eyes and face.
3. Foetal stage
At around 30 days after fertilisation, male and female characteristics show. Over the next few weeks rapid development of the foetus occurs and from day 57 (after fertilisation), live full term puppies can be born. The normal duration of pregnancy is 60 days (+/- 1 day) from fertilisation (or about 63 days from ovulation).
I must be able to use the kingfisher fact for something!
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