BIOLOGY OF EGGS AND IMPLANTATION 



809 



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GRANULOS^I^LL l'^^'' / / 



PROCESSES MICROVILLI 



ZONA PELtuClDA 



Fig. 14.6. An electron micrograph of a small segment of a multilaminar follicle from a 15- 

 day-old rat. The peripheral location of the Golgi elements, its parallel stacked double mem- 

 branes and associated vesicles are well shown. The relations between the microvilli and the 

 granulosa cell profiles in contact with the oolemma may be observed. (Courtesy of Dr. L. 

 Odor.) 



follicles before zona pellucida formation. 

 Large mitochondria with relatively few 

 cristae are present also and at this stage are 

 rather evenly distributed throughout the 

 egg. 



As the egg continues to develop the fol- 

 licle becomes multilayered and the Golgi 

 complex now appears as a number of smaller 

 units with a complex of stacked, parallel, 

 double membranes lying relatively near the 

 surface of the egg (Fig. 14.6). The mito- 

 chondria and other organelles also assume a 

 more peripheral position. The behavior of 

 the Golgi complex varies greatly from ani- 



mal to animal (Zlotnik, 1948), and there 

 are diverse opinions concerning its role 

 in yolk production. Some investigators sug- 

 gest that the Golgi material is concerned 

 with the production of protein yolk, where- 

 as others, working on different animals, 

 maintain that it is always associated with 

 the fatty yolk (Gresson, 1948 ». 



During the early stages in the develop- 

 ment of the follicle, the Golgi material in 

 those cells arranged to form the corona 

 radiata lies nearest the zona pellucida. Small 

 granules from the vicinity of the Golgi ma- 

 terial have been described, in fixed and 



