( 6 ) extra heterochromatin from either the x or y chromosome in either the mother or her progeny can reduce the mortality caused by da in development ( and , therefore , conceivably can also reduce the abnormality in oogenesis , although this is obscured by the severity of the maternal effect . ) -from these results , it is suggested that ( 1 ) da regulates either the activity of structural genes in the sex chromosome heterochromatin or the activity or stability of their products , and ( 2 ) it is a defective product of sex chromosome heterochromatic genes that causes the abnormalities resulting in the observed mortality of heterozygous progeny of homozygous mutant mothers and of homozygous mutant progeny of heterozygous mothers.-the striking parallels with the properties of the gene , `` '' abnormal oocyte '' '' are noted as is the close linkage between the two loci .
C0029047
oogenesis
C0029045
oocyt