External appearance
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Now the light beam is directed ventrodorsally. Blood vessels can be seen in one side, near the end of the egg (top left in the picture)
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Now the light beam is directed latero-laterally. The blood vessels can be seen in the lower part of the egg (bottom right in the picture)
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When I made this picture I didn't rotate the egg. I leaned it on the thumb while keeping the egg in a vertical position. It seems that the embryo is forming near one of the poles of the egg, ventrally and lateral. I made a mistake not marking the top of the egg. Now I am not sure if the egg could have been slightly rotated without noticing while handling it to take the pictures. It shouldn't be a problem for the embryo but now I am not sure if this is the position where the embryo started developing. I will mark them for future pictures. I will also mark the eggs of the second clutch (wich I can already palpate) to compare the development.
Regarding egg handling, it is interesting what A.C.Highfield wrote in "Practical Encyclopedia of keeping and breeding Tortoises and Freshwater turtles" pg31. He made experiments gently turning eggs in mid incubation. It didn't affect the egg viability, although some tortoises hatched turned.
He considers that it is a myth that you have to collect the eggs exactly in the same position they were buried. It is later, when the embryo is forming, that it is more suceptible to movement and rotation.
I have made a quick search in internet about the effects of rotation of chelonian eggs during incubation but I didn't find any specific study. There is plenty of advice against rotating them and embrionary failures attributed to rotation but I couldn't find an specific study about it. I will have a look at the references in the books I have home.
When I made this picture I didn't rotate the egg. I leaned it on the thumb while keeping the egg in a vertical position. It seems that the embryo is forming near one of the poles of the egg, ventrally and lateral. I made a mistake not marking the top of the egg. Now I am not sure if the egg could have been slightly rotated without noticing while handling it to take the pictures. It shouldn't be a problem for the embryo but now I am not sure if this is the position where the embryo started developing. I will mark them for future pictures. I will also mark the eggs of the second clutch (wich I can already palpate) to compare the development.
Regarding egg handling, it is interesting what A.C.Highfield wrote in "Practical Encyclopedia of keeping and breeding Tortoises and Freshwater turtles" pg31. He made experiments gently turning eggs in mid incubation. It didn't affect the egg viability, although some tortoises hatched turned.
He considers that it is a myth that you have to collect the eggs exactly in the same position they were buried. It is later, when the embryo is forming, that it is more suceptible to movement and rotation.
I have made a quick search in internet about the effects of rotation of chelonian eggs during incubation but I didn't find any specific study. There is plenty of advice against rotating them and embrionary failures attributed to rotation but I couldn't find an specific study about it. I will have a look at the references in the books I have home.
I believe that the Clemmys eggs are in a stage where I have to be very careful when hadling them, and I do not intend to rotate them, but it is good to know that it does not always mean the death of the tortoise.
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