CONCERNING CERTAIN CYTOLOGICAL CHARACTER- 

 ISTICS OF THE ERYTHROBLASTS IN THE PIG 

 EMBRYO, AND THE ORIGIN OF NON-NUCLEATED 

 ERYTHROCYTES BY A PROCESS OF CYTOPLASMIC 

 CONSTRICTION 



VICTOR E. EMMEL 



The Department of Anatomy, Washington Umversiiy Medical School 



FIVE PLATES 



CONTENTS 



Introduction 128 



Certain cytological characteristics of the erythroblasts previous to the forma- 

 tion of the non-nucleated erythrocytes or plastids 129 



1. Morphological changes during cytomorphosis 129 



a. Form changes in the cell bodj^; 25 to 35 mm. pig embryos; younger 



pig embryos 129 



b. Correlated nuclear changes 135 



c. Discussion of the occurrence of similar changes in other mammals.. 136 



2. Cytoplasmic processes 138 



3. Orientation of mature erythroblasts with reference to gravity . 140 



4. Unequal reaction of cytoplasmic and nuclear poles to osmotic changes . 141 



5. Discussion with reference to certain problems in the cytomorphosis of 



the mamalian erythrocyte 143 



a. The question of the correlation of the form of the definitive plastid 



with nuclear extrusion 143 



b. Possible factors accounting for the eccentric position of the nu- 



cleus in the erythroblast 146 



The origin of non-nucleated erythrocytes or plastids 148 



1. Structural characteristics of the non-nucleated erythrocytes or plastids 



in 10 to 35 mm. pig embryos 1-18 



2. The origin of non-nucleated red corpuscles in blood cultures 150 



a. Material and methods 151 



b. General characteristics of the erythrocytes as first observed in the 



cultures 153 



c. Derivation of plastids from erythroblasts by a process of cyto- 



plasmic constriction 154 



127 



THE AMERICAN JOURNAL OF ANATOMY, VOL. 16, NO. 2 

 MAY, 1914 



