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Wound healing has been studied in the surface ectoderm overlying the midbrain region of stages 16-20 chick embryos by light microscopy, scanning and transmission electron microscopy, and immunofluorescent techniques. The embryos were divided into 6 groups, i.e. stages 16-17 for groups I, V and VI, and stages 19-20 for groups II, III and IV. For groups I and(More)
The spatial and temporal distribution of apoptosis in the dorsal midline of the developing chick hindbrain was examined in relation to the development of the neuroepithelium and neural crest using scanning and transmission electron microscopy, immunocytochemistry and in situ hybridization. The pattern of TUNEL labeling and Slug expression in the dorsal(More)
PC12 cells were grown in monolayer cultures either as untreated controls or treated with (1) NGF, (2) mitomycin C/BUdR, or (3) a combination of NGF and mitomycin C/BUdR. The cells from these four groups were processed for scanning and transmission electron microscopy and for fluorescence histochemistry. With scanning electron microscopy, the control and(More)
Recent paleoclimate reconstructions have challenged the traditional view that Northern Hemisphere insolation and associated feedbacks drove synchronous global climate and ice-sheet volume during the last glacial cycle. Here we focus on the response of the Patagonian Ice Sheet, and demonstrate that its maximum expansion culminated at 28,400 ± 500 years(More)
Cranial neural fold fusion in the chick embryo is known to commence in the midbrain region before progressing cranially and caudally to involve the fore- and hindbrain regions, respectively. The two epithelial layers at the tips of the neural folds that participate in fusion are the surface ectoderm and the neuroepithelium. We have examined and compared(More)
During normal human development a number of transient structures form and subsequently regress completely. One of the most prominent structures that regress during development is the human tail. We report here a histological and ultrastructural study of cell death in the cranial and caudal (tail) parts of the neural tube in 4 to 6-week-old human embryos.(More)
Palatogenesis was studied in the ferret (Mustela putorius) from day 27 to day 29 of gestation. At day 27 the primary palate is present as a flattened shield area, and the two secondary palatal shelves are directed at 45 degrees to the horizontal plane, passing downward on the lateral sides of the tongue, which occupies the space between them. By day 28 the(More)
The endoderm of gastrulating chick embryos shows regional variations in cell shape and size. These were studied by scanning electron microscopy, histochemistry and immunofluorescence. Particular attention was given to the distribution of the cytoskeleton. Four zones of differing morphology were observed. The changing size and shape of these zones could be(More)