Question

How many eggs do you think were released by the ovary of a female dog which gave birth to six puppies?

Answer 1

Hint: During ovulation, the female ovary releases egg/ova from one of the ovaries. In humans, females release only one egg at a time of ovulation. It may differ from organisms to organisms.

Complete step by step answer:
Animals like dogs and rodents are polyovulatory species. Peri ovulatory species are those species where poly-ovulation takes place. Polyouvlation means the releasing of more than one egg at single ovulation.
There are two possible situations by which female dog can give rise to six puppies:
The female dog must-have releases six eggs from the ovaries. Each of these six eggs gets fertilised and becomes zygotes. Finally, these zygotes developed into the babies (puppies). Therefore the female dog released six eggs, to give birth to six puppies.
Another possible situation is that, if the fertilisation has taken place, which is followed by the fission. The fission can divide the single egg into six fertile zygotes which can develop into the puppies. Similar happens in case of human’s identical twins. The single egg is divided into two zygotes and gives rise to an identical twin.
Both situations are possible in this case. But a dog is a polyovulatory animal so the first situation is more possible in this case.

Additional Information: In a dog, the sexual maturity or puberty occur around 9-10 months of the age. This may differ from breed to breed. The smaller breed dog undergoes earlier in estrus as compared to larger breed dogs. The estrus occurs every six months. The interval between each estrus is about 4 -12 months and it lasts for about two to three weeks. Mostly the dog ovulates during the eleventh day of estrus.

Note: In mammals, the ovulation phase is activated by Luteinizing hormones (LH). The female dog ovulated within 48 hours of LH surge or post LH (day 2). The most important hormone is estrogen. When the LH surge the estrogen level decreases and progesterone level increases.