摘要:

AbstractAdministration of x‐rays (4000 r) to lumbar spinal cords of three‐day‐old rats caused a loss of neuroglia with an inhibition of myelinogenesis, neuronal damage and necrosis. In contrast, the loss of neuroglia following administration of 2000 r is temporary, with myelinogenesis occurring later than normal. Preliminary observations suggested that differences in vascular responses to these two amounts of x‐rays might account for these differing fates of the spinal cords; therefore, this investigation was designed to study further the reactions of the intramedullary vessels.Rats, irradiated when three days of age, were killed 1 to 27 days later. Some were killed by perfusion with Monolite Fast Blue BNVSA Paste, a substance retained in the vessels and readily visualized on microscopic examination. The remaining rats were decapitated, and spinal cords were stained by Gomori's method for alkaline phosphatase. The earliest consistent alteration, a decreased number of vessels, was noted seven days following irradiation with either dose. Rats receiving 4000 r had marked losses of blood vessels, vasodilatation and necrosis by 15 days post‐irradiation; whereas, a decreased number of vessels was the only change noted in rats irradiated with 2000 r. Alterations in rats receiving 4000 r remained the same or became more severe throughout the study; spinal cords in rats receiving 2000 r returned to normal. These vascular alterations correlate well with the changes in other spinal cord components described previously by this inv

ISSN:0003-276X    

DOI:10.1002/ar.1091630111

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

年代:1969

数据来源: WILEY

摘要:

AbstractThe fine structure of satellite cells surrounding neurons in the superior cervical ganglia of the rabbit is described. These observations form a basis for the interpretation of fine structural changes which occur in the satellite cells after post‐ganglionic section. Early changes consist of an increased number of micropinocytotic vesicles indicating an enhanced uptake of extracellular materials. The mitochondria increase in length and lie close to the plasma membranes, reflecting the increased energy requirement of these cells. Many develop intramitochondrial granules which may be concerned with the transport of water or ions. Later, at the height of chromatolysis, the satellite cells increase their quantity of granular reticulum and many possess agranular sub‐surface cisternae whose function may be to direct material synthesised in the satellite cells to the nerve cell surface. Individual layers of satellite cell cytoplasm may slide over one another to accommodate the increased size of the neurons during chromatolysis. The satellite cell processes appear thickened and contain large numbers of fine filaments which may be formed by the breakdown of microtubu

ISSN:0003-276X    

DOI:10.1002/ar.1091630112

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

年代:1969

数据来源: WILEY

摘要:

AbstractCounts of differentiating motor cells over the length of the brachial lateral motor column (LMC) indicate that a large decrease in cell number takes place during the larval period. During the same period an increase in nuclear size of the motor cells occurs with a maximum size attained just following forelimb emergence. Comparison between development of the LMC at the brachial and lumbo‐sacral levels indicates a slight lag in brachial LMC development. Cell number remains greater in the brachial LMC than in the lumbo‐sacral LMC, but nuclear size is consistently less in the brachial column. Probably no significant change in cell number occurs after metamorphosis, though there is an increase in cell s

ISSN:0003-276X    

DOI:10.1002/ar.1091630113

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

年代:1969

数据来源: WILEY

摘要:

AbstractThe ultrastructural effect of progesterone, alone and in combination with estrogen, on smooth muscle cells of the rat uterus was studied. Adult, bilaterally ovariectomized rats were untreated (controls) or treated with either progesterone (1 mg), estrogen (1 μg) or both on three consecutive days.Uterine muscle cells appeared larger and myofilaments more abundant in the progesterone‐treated rats than in the other groups of animals. Many micropinocytotic vesicles and several dense bodies were present in muscle cells of control, progesterone and estrogen‐progesterone‐treated rats. In the progestrone‐treated group, smooth muscle cells contained little granular endoplasmic reticulum and few ribosomes and glycogen particles, similar to the controls. Mitochondria were more numerous than in the control animals but similar to those seen in the estrogen or estrogen‐progesterone‐treated rats. Although an accumulation of granular endoplasmic reticulum, free ribosomes, glycogen particles and extensive Golgi complexes occurred in both estrogen and estrogen‐progesterone‐treated rats, they were more extensive in the former group.The observations indicate that progesterone alters the ultrastructure of the smooth muscle cells but not to the degree observed following estrogen stimulation. It does not markedly inhibit the effect of estrogen on the fine structure of the uterine smooth muscle cells. These observations support previous biochemical studies on glycogen concentration, RNA and protein synthesis i

ISSN:0003-276X    

DOI:10.1002/ar.1091630114

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

年代:1969

数据来源: WILEY