摘要:

AbstractEstrogen is concentrated within cellular nuclei in discrete regions of the monkey brain 30 and 60 minutes following intravenous injection of [3] estradiol. Chromatographic data is provided to suggest that most of the localized estrogen is in the form of estradiol with lesser amounts of estrone and estriol. Three “major” areas of estrogen accumulation include: (1)preopticostrial accumulation: n. preopticus medialis — n. interstitialis striae terminalis, (2)basal hypothalamic accumulation: n. infundibularis — n. ventromedialis — n. premammillaris ventralis, and (3) theamygdaloid accumulation. Several “minor” areas of estrogen accumulation include the tuberculum olfactorium, insulae Calleja, n. triangularis septi, a. hypothalamica anterior, n. anterior hypothalami, n. paraventricularis, n. supraopticus, n. periventricularis and the substantia grisea centralis. The neocortex, rhombencephalon and spinal cord are essentially unlabeled. The major areas of accumulation are similar in several other mammalian and avian species while these, and some minor areas of accumulation, have been shown in neuroanatomical studies to be interconnected by several pathways, especially the stria terminalis. Lesion, implant, stimulation, recording and morphometric studies, in several species, support the concept that this arrangement provides a neuroanatomical substrate which would allow the integration of the various facets of the neuroendocrine reproduc

ISSN:0092-7317    

DOI:10.1002/cne.901600402

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

年代:1975

数据来源: WILEY

摘要:

AbstractThe cytoarchitecture of the optic tectum of the nurse shark is described and related to the arrangements of afferents from retina, telencephalon and contralateral tectum. Its lamination is not pronounced when compared to tecta of most other non‐mammalian species but more comparable to those of mamals. The absence of highly differentiated cells such as pyramidal and true horizontal cells is perhaps correlated with the poor differentiation in general, including the apparent partial overlap of inputs. Some neurons near the midline were found to posses dendrites extending into the contralateral tectu

ISSN:0092-7317    

DOI:10.1002/cne.901600403

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

年代:1975

数据来源: WILEY

摘要:

AbstractIn the spinal ganglia of two species of reptiles (gecko and lizard) the volume of the perikaryal satellite cell sheath was found directly proportional both to the volume and surface area of the related neuronal body. This result agrees with that obtained in a previous research on two species of mammals (cat and rabbit). A quantitative balance between neuronal bodies and their associated glial tissue therefore exists also in the spinal ganglia of zoological species phylogenetically quite distant from mammals.The quantitative relationship between glial and nerve tissue was found to be lower in the gecko and lizard than in the cat and rabbit. This difference could have a phylogenetic significance, and/or it could be explained by the lower metabolic rate in the nervous system of the poikilotherms in respect to mammals.

ISSN:0092-7317    

DOI:10.1002/cne.901600404

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

年代:1975

数据来源: WILEY

摘要:

AbstractThe cycle time of the proliferating glial cells outside the subependymal layer of the lateral ventricle as well as that of endothelial cells was studied autoradiographically in the brains of adult and untreated mice. To determine the mean cycle time two independent methods were used. A mean cycle time of about 20 hours was obtained for glial and endothelial cells from the decrease of the mean grain number/nucleus as a function of time after tritiated thymidine (3H‐TdR) injection.Another group of experiments utilized the “method of labeled S phases.” With this method the passage of labeled cells through successive S phases is observed. Passing through S phase following3H‐TdR injection the3H‐labeled cells are double labeled by an additional14C‐TdR injection. This method again resulted in a cycle time of 20 hours for glial and endothelial cells. From the present work and a former study (Korr et al., 11973) the following cell cycle parameters were derived: Cycle time 20 hours; S phase 9.4 hours; G2less than three hours; (G2+ M) five hours; G1five hours. The growth fraction of glial cells related to all glial cells is only 0.004.Furthermore, the present experiments show that in the case of glial cells 17% of the daughter cells after mitosis become pyknotic and are eliminated from the glial cell population. Apart from this cell loss, after mitosis about onefourth of the daughter cells do not enter the next S phase. These cells leave the growth fraction and are replaced by a corresponding number of non‐proliferating glial cells. There is a relatively extensive permanent exchange of cells between the growth fraction and non‐growth fractio

ISSN:0092-7317    

DOI:10.1002/cne.901600405

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

年代:1975

数据来源: WILEY

摘要:

AbstractRapid Golgi impregnations of the ascending branches of the auditory nerve fibers and of the types of neurons in the anteroventral cochlear nucleus (AVCN) were studied. Entire ascending branches could be observed; some of these branches project to each subdivision, others do not. There are two main types of large neurons: the bushy and stellate cells. Criteria were established for identifying unimpregnated bushy and stellate perikarya by means of Nomarski optics, and these criteria were checked by Nomarski observations on neurons which had either impregnated dendrites and unimpregnated cell bodies or impregnated portions of perikarya. In this way, the relations of unimpregnated cell bodies to auditory nerve endings were observed. Furthermore, with Nomarski optics, the cytoarchitectonic subdivisions of AVCN could be determined. Differences in the end‐bulbs and collateral endings formed by the auditory nerve fibers were distringuished in three of the cytoarchitectonic subdivisions of the AVCN. End‐bulbs in the anterior division were much larger than those in the dorsa and ventral parts of the posterior division. The large end‐bulbs of held in the anterior division of the AVCN were consistently associated with the perikarya of bushy cells and not with those of stellate cells. The large end‐bulbs are not observed in the posterior division. Thus, bushy cells in the posterior division, although morphologically similar to those in the anterior division, must have a different synaptic organization. This difference may correspond to electrophysiological distinctions in the time‐patterns of response recorded in these regions following acoustic st

ISSN:0092-7317    

DOI:10.1002/cne.901600406

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

年代:1975

数据来源: WILEY

摘要:

AbstractAlthough the inferior olivary nucleus of the opossum is small, sections stained either for Nissl substance, normal axons or cholinesterase activity reveal distinct medial, dorsal and principal nuclei. The medial nucleus contains three major subdivisions (labelled a, b, c after Bowman and Sladek, 1973) and a group of neurons which is comparable to the cap of Kooy. In contrast to the cat and monkey, the major portion of the “medial” nucleus (subgroup a) lies lateral to the principal nucleus in rostral sections. The dorsal nucleus can also be subdivided, as can the principal nucleus which contains distinct dorsal and ventral lamellae. A small area is identified which based on position and connections may conform to the dorsal medial cell group.The experimental portion of the study provides evidence for an olivary projection from the motor‐sensory cortex and a massive input from the midbrain (red nucleus, pretectum, midbrain tegmentum). In addition, the opossum inferior olive receives fibers from the deep cerebellar nuclei (cerebellar feedback loops), the spinal cord and the dorsal column nuclei. Of particular interest is the finding that fibers from the nucleus cuneatus and nucleus gracilis have distinctly different olivary targets and that those from the nucleus gracilis, but not the cuneate nucleus, overlap (in part, at least) with the direct spinal fibers. Other examples of overlapping fields of terminal degeneration are present and are discussed. In general our results reveal that although certain relationships between the nuclear divisions are different, the opossum olive conforms well to that of placental mammals and provides a basic mammalian model for future experimental electron microscopic and physiological st

ISSN:0092-7317    

DOI:10.1002/cne.901600407

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

年代:1975

数据来源: WILEY

摘要:

AbstractCell counts were made in the lumbar lateral motor column (l.m.c.) of chick embryos of 5.5, 6, 7, 8, 9, 12, 18 days of incubation and five days posthatching (n = equals; 68). Only nuclei with nucleoli were counted and corrections were made for double counting (Abercrombie, 1946). The population attains a peak value of over 20,000 cells (corrected figure: over 17,000) at 5.5–6.5 days = stages 28 and 29 (Hamburger and Hamilton, 1951). The l.m.c. loses between 7,000 and 8,000 cells between days 6.5 and 9.5, (between stages 29 and 36). In other words, 60% of the population survive. A plateau of approximately 12,300 cells (corrected figure: 10,300) is maintained throug five days posthatching. Massive cell degeneration was observed in 7‐ and 8‐day embryos. Counts of distinctly pyknotic cells indicate that at least 5–6% of the total population is in the process of degeneration at any particular time. This figure is probably an underestimation; hence it is virtually certain that the depletion of the l.m.c. is due entirely to cell death. Arguments are presented in support of the hypothesis that the naturally occurring cell death in the l.m.c. is due to the failure of their axons to survive in a competion process at the periphery. Observations of the time pattern of muscle differentiation and their neurotization in the leg further endorse this hypothesis. However, it is not clear whether the axons compete for contact sites on muscle fibers or for a “troph

ISSN:0092-7317    

DOI:10.1002/cne.901600408

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

年代:1975

数据来源: WILEY

ISSN:0092-7317    

DOI:10.1002/cne.901600401

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

年代:1975

数据来源: WILEY