摘要:

AbstractThe development of the central nervous system of the sheep foetus with particular reference to myelin forming cells and myelination has been studied by morphological and histochemical methods. The development of the spinal cord resembles that described for other species and broadly similar patterns of development have been found for the other major regions. Differentiation of definitive cell types is marked by the appearance of cytochrome oxidase activity in their cytoplasm. In gray matter strong cytochrome oxidase activity persists into post‐natal life whereas in white matter activity declines following commencement of myelination.Lipids having the histochemical reactions of myelin first appear in a particular region as the capillary circulation of that region develops. It is suggested that phospholipid elements of perivascular lipid may be rapidly incorporated into the developing myelin sheath whilst galactolipids from the same location are more slowly utilized. The implications of the findings are discusse

ISSN:0092-7317    

DOI:10.1002/cne.901350302

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1969

数据来源: WILEY

摘要:

AbstractStudies on the postnatal development of Clarke's column were undertaken in order to ascertain if there were changes observed morphologically that would be compatible with the results so far reported both anatomically and physiologically on the afferent supply and the cerebellar end‐point of this system. The studies were carried out on the L.2 and L.3 segments of the spinal cord of kittens ranging in age from newborn to eight weeks. The principal staining methods employed were the Ha modification of the Golgi‐Cox, the Rasmussen technique for synapses, and Bodian's fiber stain. The sections were viewed using substage and reflected illumination.The most pertinent findings involved (1) the number of synapses and their distribution over the cell body and dendrites and (2) the number of stem dendrites and their orientation. There is an apparent lack of stainable synapses at birth, by eight days synaptic endings are present and by three weeks the entire cell is encrusted with two distinct types of synaptic end bulbs. Regarding the second point, a noticeable decrease was seen in the number of stem dendrites with a concomitant centripetal orientation of the dendritic tree in relation to the center of Clarke's column. The significance of these changes on the maturation of Clarke's column, on its afferent input and on the development of the dorsal spinocerebellar tract as a functional system is discus

ISSN:0092-7317    

DOI:10.1002/cne.901350303

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1969

数据来源: WILEY

摘要:

AbstractA comparative and quantitative anatomical study of the cerebral ventricular system of the dolphin,Tursiops truncatus, and six other mammalian species, including man, has been made in the course of extensive neuroanatomical investigations of the dolphin. Several techniques have been used in these studies to confirm the morphological arrangement and contours of the ventricles. Casts of the ventricles were produced by use of a variety of casting media and methods and their relative merits were investigated and described. Following injection of the brain with casting media, the brain was either totally removed by dissection or digestion or one hemisphere dissected away to reveal the relationships of the ventricular cast to the opposite cerebral hemisphere. Serial sections of the brains of three dolphins were cut in three cardinal planes, and from these a model of the entire ventricular system was reconstructed. Serial sections (Nissl and Loyez) were also used to identify structures closely related to the ventricular cavities. Our results show that components of the cerebral ventricular system of the dolphin reflect, to a considerable degree, many of the specialized features of that brain including brachycephaly, widened and foreshortened temporal lobes, large limbic lobe, hypodeveloped frontal region, absence of an occipital pole, and massive development of the tectal acoustic apparatus. The morphological characteristics of the ventricular system and the relationship of this system to brain areas is discussed with respect to possible functional and phylogenetic implications.

ISSN:0092-7317    

DOI:10.1002/cne.901350304

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1969

数据来源: WILEY

ISSN:0092-7317    

DOI:10.1002/cne.901350301

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1969

数据来源: WILEY