journal article
LitStream Collection
Home
Ross, William T.; Cardell, Robert R.
doi: 10.1002/aja.1001350103pmid: 4341641
The objective was to study the effects of halothane, a volatile anesthetic, on hepatic metabolism of a second volatile anesthetic, methoxyflurane, and to correlate these biochemical findings with hepatic morphological changes. Microsomal fractions isolated from rats treated with halothane and from control animals were assayed for their capacity to dechlorinate methoxyflurane. Microsomes from halothane‐treated rats demonstrated about 2.6 times the capacity to dechlorinate methoxyflurane as microsomes from control animals. Electron microscopy showed that liver cells from halothane‐treated animals, when compared with hepatocytes from control rats, had increased amounts of smooth endoplasmic reticulum, an increased number of lipid droplets, and more microbodies per cell. Rough endoplasmic reticulum and glycogen were decreased by halothane treatment. We interpret these results to mean that halothane induces the rough endoplasmic reticulum to synthesize enzymes required for the biotransformation of methoxyflurane. It is suggested that these enzymes are placed in membranes of the rough endoplasmic reticulum. This organelle is converted to smooth endoplasmic reticulum and here the biotransforming enzymes function to dechlorinate methoxyflurane.
Ellison, Jeffrey P.; Olander, Kenneth W.
doi: 10.1002/aja.1001350104pmid: 4560620
Certain primary catecholamines remain well localized during brief fixation with cold, buffered formalin. In the present study, the diffusibility of catecholamines was further explored, using guinea‐pigs and cats pretreated with Nialamide and norepinephrine. Preliminary experiments showed that catecholamines were well localized after perfusion fixation with buffered formalin. Furthermore, catecholamines remained in situ in tissues immersed in cold fixative or phosphate buffer for as long as six hours. It seemed, therefore, that catecholamines might remain localized in fixed tissue, during incubation for acetylcholinesterase. To test this hypothesis, formaldehyde‐fixed, cryostat sections were incubated in a cold thiocholine medium for two to four hours to demonstrate acetylcholinesterase activity. They were then exposed to formaldehyde gas to demonstrate catecholamines. Acetylcholinesterase‐positive and catecholaminecontaining nerve fibers were identified simultaneously in the same section under mixed ultraviolet and red light. When a dark‐field condenser was used, adrenergic nerves appeared green and acetylcholinesterase‐positive nerves red on a black background. We were able to demonstrate adrenergic presynaptic terminals on cholinergic myenteric ganglion cells and acetylcholinesterase‐positive terminals close to cardiac chromaffin cells. We also have observed contiguities between peripheral adrenergic and cholinesterase‐positive nerves.
Rosa, Charles G.; D'Angelo, Savino A.
doi: 10.1002/aja.1001350105pmid: 5069144
Adenohypophyses of rats were studied ultrastructurally to ascertain the morphologic changes that occur in thyrotropic cells during the pituitary TSH Rebound Phenomenon. Rats were maintained on propylthiouracil (PTU) for 43–147 days and their adenohypophyses studied three to nine days after discontinuance of goitrogen treatment. TSH rebound was also induced in chronically hypothyroid rats by single intravenous injections of 0.8, 4, 20 and 200 μg of thyroxine. Pituitaries were studied from animals sacrificed 6–24 hours after thyroxine injection. Thyrotrophs of euthyroid rats were characterized ultrastructurally by the presence of numerous peripherally‐located, small secretory granules (storage phase) and by highly dilated cisternae of rough endoplasmic reticulum (secretory phase). The thyrotropic cells in PTU‐treated rats were sparsely granulated, displayed enlarged mitochondria with much loss of cristae and contained extensively dilated rough endoplasmic reticulum and expanded Golgi membranes.
Swartz, William J.; Domm, L. V.
doi: 10.1002/aja.1001350106pmid: 5069145
The purpose was to determine the sites, times and frequency of mitotic activity in primordial germ cells in the white Leghorn chick embryo during the period of migration. Colchicine was employed to facilitate the identification of dividing germ cells in embryos ranging in age from 18 hours to five days of incubation (stages 3–27). An increase in the number of germ cells was observed during the period of migration, due primarily to proliferation of intraembryonic cells, since no significant increase in the number of extra‐embryonic germ cells was seen during this period. The number of germ cells during this period ranged from 43 at 18 hours to 2211 at 120 hours. Two periods of intense proliferation were observed, the first between 48 and 72, the second between 96 and 120 hours. This coincided with a simultaneous increase in the number of germ cells during these periods. Dividing germ cells were present in the extraembryonic blood vessels anterior, lateral and posterior to the embryo at 28, 48 and 72 hours and within the intra‐embryonic circulatory network at 48, 72, 96 and 120 hours. At 72, 96 and 120 hours, dividing germ cells were numerous in the tissues of the dorsal mesentery adjacent to the developing gonads and within the gonads. Dividing germ cells were also located in head mesenchyme, limb buds and mesenchyme surrounding the notochord‐neural tube complex. Dividing germ cells were found in the chick embryo throughout the entire migratory period.
doi: 10.1002/aja.1001350107pmid: 5069146
Parotid acinar cells from ad libitum‐fed and starved rats were studied using electron microscopic and cytochemical techniques. Lysosomes containing acid phosphatase and non‐specific esterase activity were present in cells of both ad libitum‐fed and starved rats. They included lipofuscin‐like bodies, smaller round or irregularly‐shaped bodies, multivesicular bodies, and coated vesicles. After 16–24 hours of starvation, lipid droplets had accumulated in the basal cytoplasm, and secretory granules showed evidence of degeneration. These altered granules consisted of irregular clumps of dense material in a less dense matrix. After 48–72 hours of starvation, the altered granules increased in number and fused to form large aggregates. Some of the aggregates also contained vesicles, membranous material, and lysosomal residues. The altered granules and aggregates were reactive for acid phosphatase and non‐specific esterase. The formation of the altered granules appeared to occur by spontaneous degeneration of the secretory granules, with secondary fusion with pre‐existing lysosomes and other altered granules. The results suggest that the lysosomal system of the parotid acinar cell functions to segregate and digest secretory granules during periods of reduced secretory stimulation.
Nakayama, Iwao; Nickerson, Peter A.
doi: 10.1002/aja.1001350108pmid: 4341642
Membranous and vacuolar inclusions have been identified within the nucleus of mammotrophs in the pituitary of female Mongolian gerbils but are absent in adult male and newborn gerbils of both sexes. Membranous inclusions are observed in focal areas of the nucleus and are frequently in proximity to the inner nuclear membrane. Vacuoles are surrounded by a single membrane and the matrix is structureless and either flocculent or clear. An intermediate form of nuclear inclusion is membrane‐bound and contains typical cytoplasmic organelles. It is suggested that degenerative changes in inclusions originating in the cytoplasm may produce large structureless vacuoles. The increased number of inclusions in testosterone‐treated animals may be a response of mammotrophs to alteration in synthesis or release of hormone.
doi: 10.1002/aja.1001350109pmid: 5069140
Comparison of the effects of the Da gene upon the spheno‐occipital synchondrosis in rabbits of strain DA and unrelated strain IIIDa has made possible study of the relative effects of Da growth retardation and strain differences of primary and secondary growth gradients and their interaction. When Da is absent and parental border shift dosages (which portray the localization and magnitude of thoracic and lumbar gradients) are most anterior, synchondrosis fusion is minimal in both strains. Presence of Da in either Da/+ or Da/Da genotype significantly increases the penetrance and expression of fusion in both strains. Fusion tends to be additively increased when parental thoracolumbar and lumbosacral borders are shifted anteriorly, and antagonistically decreased when they are replaced by posterior border shifts. The interaction of these two (gene and genome) influences results in patterns of continuous distribution involving from two to five classes. Penetrance of fusion is outstandingly affected by Da whereas expressivity obviously is more specifically associated with vertebral border shifts. This differentiates their associations with primary and secondary gradients respectively. The study shows how such epigenetic variants and specific gene induced localized retardations could be used in genetic analyses of basic growth processes. Studied developmentally in time and relation to function, they could establish firm grounds for prediction and control of abnormal development.
doi: 10.1002/aja.1001350110pmid: 4627010
After formation of the epididymis, the cuboidal epithelial cells of the ductus epididymidis undergo little cytodifferentiation in the fetal rhesus monkey. However, from 130 days of fetal life until birth, the cells undergo a period of differentiation that proceeds in an anterio‐posterior direction along the duct. Concurrently epithelial cells of the ductus efferens and caput epididymidis transform from a cuboidal condition with no surface modifications to cells similar to those of adults. Over 50% of the cells become ciliated and the remainder develop surface modifications resembling those in adult nonciliated cells. The epithelial cells lining the ducts of the corpus epididymidis, and in some cases those of the cauda epididymidis, develop stereocilia.
Showing 1 to 10 of 14 Articles