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Abnormal differentiation of selected nuclear centers in the brain of a duck embryo associated with partial duplication of the primitive streak
Author(s) -
Narayanan C. H.,
Narayanan Y.
Publication year - 1982
Publication title -
journal of morphology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.652
H-Index - 74
eISSN - 1097-4687
pISSN - 0362-2525
DOI - 10.1002/jmor.1051720304
Subject(s) - biology , primitive streak , embryo , anatomy , gene duplication , primordium , embryogenesis , microbiology and biotechnology , genetics , gastrulation , gene
In a control set of duck embryos, and abnormal duck embryo of 16 days incubation was found which had two beaks as the only outward sign of duplication. The beaks were of equal size, each with upper and lower bills. Billclapping movements were absent. The embryo had two normal eyes placed one on either side of the head, and the rest of the body was normal in external appearance. Sections through the head revealed further duplication of the fore‐, mid‐, and hindbrain divisions. The medial half of each of the embryonic brain divisions, however, was greatly reduced. Two additional optic primordia were also noticed in sections, each of which was reduced to a mass of tissue representing a lens and a much‐folded pigment epithelium. The orbital tissues associated with the rudimentary eyes were greatly disorganized. Abnormal differentiation associated with duplication of the brain divisions was determined by cell counts in selected nuclear centers. Cell numbers in each case appeared to be remarkably proportional to the size of the innervation field. Our data, based on cell counts in the nuclear centers chosen for this study in the abnormal embryo and normal control embryos of the same age, are consistent with the hypothesis that cell survival in related parts of the nervous system may be regulated by their peripheral field of innervation.