Intramitochondrial Yolk-Crystals of Frog Oocytes

Abstract

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 µ mean diameter . The hexagonally shaped yolk-crystals have major periodicities of 73 .8 f 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 .

Vitellogenesis and Oocyte Growth in Nonmammalian Vertebrates

“…These inclusions were interpreted at the time as representing progenitors of the crystals formed within the oocyte yolk platelets. Intramitochondrial yolk crystals were then observed and similarly interpreted by many others (see Massover, 1971a and references cited therein). Massover (1971b) also provided evidence that yolk crystals in Rana catesbeiana oocytes were extruded maturation, yolk polypeptides formed during vitellogenesis-notably those with molecular weights of 120,000 and 45,000 in Band 28,000 and 14,000 in b-disappear, and new lowermolecular-weight bands appear in C and c. A comparison of follicles matured in vivo (C, c) and in vitro (D, d) according to the procedures of Wallace and Selman (1978) reveals no fundamental differences, indicating that the proteolytic processes that occur during maturation in vivo can be achieved in vitro simply by adding deoxycorticosterone to postvitellogenic follicles such as those used for lanes Band b.…”

Ultrastructural aspects of oogenesis and oocyte growth in fish and amphibians

“…These were interpreted at the time as representing progenitors of the crystals found within the oocyte yolk platelets. Intramitochondrial "yolk crystals" were then observed and similarly interpreted by many others in this country as well as in Europe and Japan [see Massover (1971a) for literature citations]. Massover (1971b) also provided evidence that yolk crystals in R .…”

Ultrastructural and histochemical study of the salivary glands of Aplysia depilans (Mollusca, Opisthobranchia)

“…In the salivary glands of A. depilans , intramitochondrial crystals were found only in the vacuolated cells, but mitochondria with crystalline inclusions have previously been reported in other animal and plant cells (Tandler and Hoppel 1972). For example, in the mitochondria of the bullfrog oocytes, hexagonal‐shaped yolk crystals were observed within the intermembrane space (Massover 1971) and in the epitheliomuscular cells of Hydra rhomboidal or rectangular crystals were detected in the mitochondrial matrix (Davis 1967). The intramitochondrial crystals of Hydra resemble those described in A. depilans , but in this last species the crystals were much larger.…”