CELLULAR ELEMENTS OF THE MAMMALIAN EMBRYO 93 



V. ERYTHROCYTIC DISINTEGRATION IN THE MESENCHYMA 



1. Degenerative changes in erythrocytic nuclei with reference to: 



a. The question of the mesenchymal secretion of erythrocytic 

 elements. The fact that degenerating erythroblasts, especially 

 their nuclei, may undergo changes resulting in the production 

 of small red spheres or masses with either central or peripheral 

 accumulations or remnants of basophilic material as observed in 

 the coelomic cavities, merits further consideration with refer- 

 ence: first, to the bodies interpreted by Maximow as mesenchy- 

 mal secretions, and second, to the ring bodies of Cabot. 



Concerning the possible relation of these eosin bodies to mes- 

 enchymal activities it may be noted that Maximow ('09, p. 513) 

 describes the observation in the blood of the embryonic rabbit 

 of apparently similar eosin-basophilic-droplets which he states 

 soon disintegrate in the circulating plasma. Maximow inclines 

 to the conclusion that these bodies are secretion products of 

 mesenchymal cells and represent an abortive or precocoius dif- 

 ferentiation of erythrocytic or hemoglobin containing elements. 

 Evidence is advanced for the occurrence of such a secretion in 

 various regions of the mesenchyma, such as that of septum 

 transversum, in the head region and adjacent to the distal ends 

 of growing blood vessels. In these regions he records the ob- 

 servation of many large and small red and blue stained spherical 

 or angular bodies generally embedded in clear vacuoles in mes- 

 enchymal cells. These bodies are described as consisting of 

 red spheres containing one or more central blue spherules, red 

 bodies furnished with one or more deep blue peripheral cres- 

 cents or caps, or blue rings filled with a clear eosin stained con- 

 tent (p. 500). After the consideration of several possibilities 

 as to their origin it is decided that they are probably elaborated 

 in situ in the mesenchymal cytoplasm and it is stated that one 

 can observe how the inclusion in the cytoplasm of the mesen- 

 chymal cell develops from a few initial small erythrocytic gran- 

 ules and how it grows in size, and the basophilic substance 

 appears within it or on its surface. 



