Intramitochondrial yolk-crystals of frog oocytes. I. Formation of yolk-crystal inclusions by mitochondria during bullfrog oogenesis.
Electron microscope examination of thin sections of bullfrog (Rana catesbeiana) ovarian oocytes has shown the presence of mitochondria containing yolk-crystal inclusions in oocytes of all sizes, from 160 to 1500 micro mean diameter. The hexagonally shaped yolk-crystals have major periodicities of 73.8 +/- 10.7 A (n = 100). Several forms of modified mitochondria, observed in the smaller oocytes, may be arranged into a series of structurally intermediate forms between standard oocyte mitochondria and the typical mitochondria with yolk-crystal inclusions. The observation of such intermediate forms is consistent with proposals that the yolk-crystal inclusions arise within a limited portion of the oocyte chondriome by a complex process of mitochondrial differentiation.
D000818:Animals; D001001:Anura / Q000196:embryology*; D005260:Female; D008854:Microscopy, Electron; D008928:Mitochondria; D009024:Morphogenesis; D010063:Ovum / Q000166:cytology / Q000254:growth & development*