chiaravi@silver.bacs.indiana.edu (Lucius Chiaraviglio) (09/11/88)
[About a tongue-in-cheek suggestion for a shuttle experiment funded by Kentucky Fried Chicken, to study chicken development in space -- actually not a bad idea, but I doubt Kentucky Fried Chicken would fund it.] In article <44600021@pyr1.cs.ucl.ac.uk> william@pyr1.cs.ucl.ac.uk writes: [Last part of the suggestion is >>] >> It may also offer clues as to how human embryos may one day >>develop in space. > >Forgive me if I am wrong, (it's a while since I studied the theory!!), >but are there portions of the human reproductive system that require >some sense of orientation prior to fertilisation? Something to do with >sperm navigation. [. . .] I very much doubt it. Remember that mammalian females change position many times between copulation and fertilization, which would really mess up gravity-dependant sperm. Also, mammalian eggs do not have the gravity- sensitive cytoplasmic determinants that amphibian eggs have (or, initially, any cytoplasmic determinants at all, it seems -- the cells formed by the first 3 divisions seem to be for all practical purposes entirely identical, and can be rearranged freely without messing up the subsequent embryo). Note that if mammalian eggs and embryonic development were gravity-dependant, it would be very hard to get them to develop properly, again due to the changing position of mammalian females (yes, vivapary does have its disadvantages). However, bird eggs (as well as reptile eggs) are even larger and yolkier than amphibian eggs, and while it is predicted that the absence of gravity will not disturb amphibian eggs (or reptile or bird eggs) -- that is, it takes gravity in the wrong direction and at the right time to mess up development -- the required data is not yet available. Experiments to test the development of amphibian and fish (similar kind of eggs and development) embryos in space are being designed in the Department of Biology at Indiana University. It is my understanding that rats were taken up on one of the Skylab flights (unless I am getting mixed up and it is the Russians that did this) and allowed to mate and produce offspring. The offspring developed completely normally, and did not even suffer the bone calcium loss that their parents were experiencing. Unfortunately, I don't have the reference for this. Anyone else know of this? -- Lucius Chiaraviglio chiaravi@silver.bacs.indiana.edu lucius@tardis.harvard.edu (in case the first one doesn't work) "NO DYING ALLOWED." -- The Maytag coin-operated washing machine instruction poster. "This would be nice!" -- graffitti seen on the Maytag coin-operated washing machine instruction poster in the Daniels laundry room in Currier House at Harvard University.
chiaravi@silver.bacs.indiana.edu (Lucius Chiaraviglio) (09/13/88)
In article <2249@silver.bacs.indiana.edu> I wrote: > [. . .] >bird eggs (as well as reptile eggs) are even larger and yolkier than amphibian >eggs, and while it is predicted that the absence of gravity will not disturb >amphibian eggs (or reptile or bird eggs) -- that is, it takes gravity in the >wrong direction and at the right time to mess up development -- the required >data is not yet available. Experiments to test the development of amphibian >and fish (similar kind of eggs and development) embryos in space are being >designed in the Department of Biology at Indiana University. I just heard a talk at the Indiana University Department of Biology retreat on space biology, which gave me some information on these matters that I hadn't heard before. One piece of information is that it looks like (but is not certain) that some of the cell migrations early in chicken development which are normally vertical or near-vertical may actually depend on gravity rather than just that gravity not be in the wrong direction. > It is my understanding that rats were taken up on one of the Skylab >flights (unless I am getting mixed up and it is the Russians that did this) >and allowed to mate and produce offspring. [. . .] I guess I must have gotten this mixed up. According to the same talk, rats were taken up on the Space Shuttle after fertilization (I'm not sure just how long after) and allowed to continue towards term; however, the Space Shuttle flights are not long enough to allow rats to develop all the way from fertilization to birth in space. The rats came back down, and the embryos which had done part of their development in microgravity were born as normal rats. -- Lucius Chiaraviglio ARPAnet: chiaravi@silver.bacs.indiana.edu BITNET: chiaravi@IUBACS.BITNET (hoses From: fields; INCLUDE RETURN ADDRESS) USENET: iuvax!silver!chiaravi -- -- Lucius Chiaraviglio ARPAnet: chiaravi@silver.bacs.indiana.edu BITNET: chiaravi@IUBACS.BITNET (hoses From: fields; INCLUDE RETURN ADDRESS) USENET: iuvax!silver!chiaravi