THE DEVELOPMENT OF THE ALBINO RAT, 
MUS NORVEGICUS ALBINUS 
II. ABNORMAL OVA; END OF THE FIRST TO THE END OF THE 
NINTH DAY 
G. CARL HUBER 
From the Department of Anatomy, University of Michigan, and the Division of 
Embryology, Wistar Institute of Anatomy and Biology, Philadelphia 
TEN FIGURES 
CONTENTS 
UTES TEMG HO ele hey 2S eh ge gah eee en re ee In ey Ae Jeo 359 
REA ALAA ay UT en AA LAY hone chars Geeue teh e0" a are a. sos ohh ig 0 Die cea ee Momsen ee 361 
Degeneration of ova at the end of segmentation......................000- 364 
incontplete or retarded segmenbatiom.:. 5. ...........>.0..<sebs modes tewecee 365 
ApnorMial sexmentation Cavity formabhiony: s... 5.4 sis . ss ves Soueee se bias 370 
Degeneration of ova as a result of pathologic mucosa..................... 373 
Imperfect development of ectodermal vesicle..................c0000eee eens 376 
iwoverp-cylinders mm: one decidual crypts... ........ ..+. eos ee ec adees seen ue 382 
BG PADALINETINOIN SA Np rrr ACORN, ted Mee Ne ke Edam. Sect av sen ssa. Sildny ov 2g RR 384 
TE SSR TERS YLT ee So Nap A ri ees SL ee 386 
INTRODUCTION 
In the course of my study of the normal development of the 
albino rat, from the end of the first to the end of the ninth day 
after insemination, as recorded in Part I of this series of contri- 
butions, there were encountered from time to time ova which 
appeared to deviate both in rate and type of development from 
what, as a result of extended study, came to be regarded as the 
normal developmental cycle of the albino rat. When taken col- 
lectively, the number of these abnormal ova is not large, al- 
though they embrace nearly all of the developmental stages 
studied. When taken singly, it may be stated that while it is 
comparatively easy to record the points of deviation from the 
normal, it must be admitted that the probable fate of the respec- 
tive stages can only be conjectured. Nevertheless, a record of 
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JOURNAL OF MORPHOLOGY, VOL. 26, NO. 2 
