Lipid droplets in the visceral yolk sac endodermal cells of the postimplantation rat embryo: application of malachite green-glutaraldehyde fixative.
The ultrastructure of the visceral yolk sac (VYS) of the rat embryo at day 9.5 of gestation was examined after fixation with either Karnovsky's glutaraldehyde-paraformaldehyde solution or malachite green-containing glutaraldehyde (MGA) solution. Fixation with MGA retained homogeneously electron-dense droplets in the cytoplasm and the nucleus of endodermal cells, both of which were lost in the specimens prepared by Karnovsky's fixation methods. The cytoplasmic MGA-positive droplets were frequently associated with other cytoplasmic organelles such as rough endoplasmic reticulum, mitochondria and membrane-delineated inclusion bodies, but these cytoplasmic organelles never incorporated MGA-positive materials, whereas Golgi apparatus contained intracisternal MGA-positive droplets. Extracellular MGA-positive droplets were also encountered at the apical surface of endodermal cells and in the intercellular space between endodermal cells and the underlying mesodermal cells. These MGA-positive droplets were considered to be lipid in nature, and their origin in the endodermal cells of VYS is discussed.
D000818:Animals; D047108:Embryonic Development; D005260:Female; D005404:Fixatives / Q000494:pharmacology*; D005557:Formaldehyde / Q000494:pharmacology; D005976:Glutaral / Q000494:pharmacology; D006651:Histocytochemistry; D050356:Lipid Metabolism; D008854:Microscopy, Electron; D011247:Pregnancy; D051381:Rats; D015017:Yolk Sac / Q000378:metabolism* / Q000648:ultrastructure
D005404:Fixatives; D005557:Formaldehyde; D005976:Glutaral