An electron microscope study on the developing oocytes of the crab Cancer pagurus L. with special reference to yolk formation (Crustacea)

Zoomorphology ◽  
1973 ◽  
Vol 75 (3) ◽  
pp. 243-254 ◽  
Author(s):  
Laila Eurenius
Keyword(s):  
Electron Microscope ◽  
Special Reference ◽  
Microscope Study ◽  
Electron Microscope Study ◽  
Yolk Formation ◽  
Cancer Pagurus

scholarly journals AN ELECTRON MICROSCOPE STUDY OF YOLK FORMATION DURING OOGENESIS IN LEBISTES RETICULATUS GUPPYI

1966 ◽  
Vol 28 (2) ◽  
pp. 209-232 ◽  
Author(s):  
Michael J. Droller ◽  
Thomas F. Roth
Keyword(s):  
Endoplasmic Reticulum ◽  
Electron Microscope ◽  
Microscope Study ◽  
Electron Microscope Study ◽  
Structural Changes ◽  
Extracellular Material ◽  
Yolk Formation ◽  
Selective Uptake ◽  
Lebistes Reticulatus

The present investigation describes the fine structural changes that occur during proteid yolk formation in the developing oocytes of the guppy (Lebistes reticulatus), an ovoviviparous teleost. These changes suggest the operation of a number of different intra- and extraoocyte processes that may account for the synthesis and deposition of the proteid yolk. Early in oogenesis, the egg's Golgi systems proliferate and begin to disclose an electron-opaque content. Numerous 70-mµ diameter vesicles apparently pinch off from the Golgi systems, transport this material through the egg, and probably then fuse to form a crenate, membrane-limited yolk droplet. At the same time, the rough-surfaced endoplasmic reticulum accumulates a flocculent substance that differs in appearance from the Golgi content. Smooth vesicles, presumably derived from the ER, then coalesce to form a second type of intraoocyte yolk droplet. These dissimilar, separately derived droplets subsequently fuse, thus combining the materials that constitute the intraoocyte contribution to the proteid yolk. Somewhat later in development, the egg appears to ingest extracellular material via 75-mµ diameter bristle-coated micropinocytotic pits and vesicles. These structures apparently fuse to form tubules which then coalesce into large yolk droplets. At a later stage, bristle-coated micropinocytotic vesicles of 100 mµ diameter presumably take up a material that is then probably immediately deposited into a second type of proteid yolk droplet. It is postulated that these two different micropinocytotic structures are specifically involved with the selective uptake of dissimilar extracellular proteid materials.

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