Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!tut.cis.ohio-state.edu!ucbvax!agate!codon1.berkeley.edu!mkkuhner From: mkkuhner@codon1.berkeley.edu (Mary K. Kuhner;335 Mulford) Newsgroups: sci.bio Subject: Re: embryology. A mini tutorial Message-ID: <23432@agate.BERKELEY.EDU> Date: 21 Apr 89 22:10:31 GMT References: <3229@imagen.UUCP> <169@ascom.UUCP> <1957@trantor.harris-atd.com> Sender: usenet@agate.BERKELEY.EDU Reply-To: mkkuhner@codon1.berkeley.edu.UUCP (Mary K. Kuhner) Organization: University of California, Berkeley Lines: 19 In article <1957@trantor.harris-atd.com> hnewstrom@x102a.harris-atd.com (Harvey Newstrom) writes: >In humans the Y chromosome produces males, while its lack produces females. >Thus, XXY is male, while XXX is female. XO is female, but I don't think any >survive in humans. XO is Turner's Syndrome in humans, and is viable--individuals are female and nearly normal, but sterile. >Sometimes humans can be mottled, with a combination of different cells! This >is caused by two cells in the beginning merging into one fetus instead of >forming twins! Or by loss or doubling of chromosomes in one cell early in development, which I believe is the more common way for this to happen, perhaps the only one (but "impossible" is a dangerous word). Mary Kuhner mkkuhner@enzyme.berkeley.edu