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Biomedical subjects

J N Scott

Publications and source records attributed to J N Scott.

50 records · Page 3Linked to original sources
PubMed1982

Retained placentas in a colony of mice.

Twenty mice were killed 1-6 days after parturition, and the uterine contents were examined grossly and microscopically. Uteri of 10 animals had retained one or more placentas, each of which was firmly attached to the uterus and usually exhibited fetal membranes and an umbilical cord. Histologic preparations revealed that the fetal blood channels in the labyrinth region were collapsed and fibrosed while some maternal blood channels were open and contained blood cells. In the junctional zone and decidua, necrosis and leukocytic invasion were evident. In median sections, a stalk of fibrous tissue extended from the uterus to the placenta.

Animals↗
PubMed1982

Developmental changes in the mouse amnion: a SEM study.

Both surfaces of the mouse amnion from 13 to 21 days of gestation were studied by scanning electron microscopy (SEM). The exocoelomic surface is covered by mesenchymal cells and randomly arranged fine fibers at 13 days. By 21 days, these cells are covered by thick fibers frequently arranged in woven pattern. The ectodermal lining of the amniotic cavity at 13 days is characterized by squamous epithelial cells with central patches of short microvilli. An apparent increase in microvilli occurs by 16 days followed by either the loss of microvilli or the formation of microridges by 21 days. These changes may reflect functional changes of the amnion or processes of cell aging.

Amnion↗
PubMed1981

Scanning electron microscopy of the decidual stalk and decidua basalis in the mouse.

Placentas either in situ or mechanically separated from their uterine beds were surveyed by scanning electron microscopy to determine the changing relationship of the placenta to its uterine bed with special reference to alteration in the decidual basalis accompanying parturition. At 13 days gestation the placenta is connected to the uterus by a short, broad decidual stalk which becomes longer and more constricted by term. The stalk is covered by a layer of squamous epithelium. Mechanical separation of the placenta and uterus in early gestation reveals that the entire decidual basalis of the decidual stalk is composed of large coarse fibers. As gestation progresses, a relatively smooth acellular capsule forms around the base of the placenta. However, the center of the decidua basalis, the core of the stalk, continues to be composed of large coarse fibers throughout gestation and appears to be the only region penetrated by maternal vessels.

Animals↗
PubMed1980

Scanning electron microscopy of fused mouse placentas and associated uterine bed.

The decidual surface of two fused placentas and the associated uterine bed were examined by scanning electron microscopy. The compact decidua basalis fits into a uterine depression filled with coarse fibers which is surrounded by a smooth area that gradually becomes folded. Placental fusion due to twinning or crowding is discussed.

Animals↗
PubMed1980

Placental changes due to administration of diethylstilbestrol (DES).

Pregnant mice were injected with 12.5 micrograms DES/kg body weight or 25 micrograms DES/kg body weight daily from gestation day 9 through day 12 or 16 and sacrificed on day 13 or 17. Placentas of DES treated animals were smaller than controls, the effect being dose dependent. Histologic changes in 13 gestation day placentas regional thinning of the labyrinth associated with an apparent inhibition of trophoblast maturation and development of fetal blood vessels. Knots of mononuclear cells form in the labyrinthine region of 13 day placentas exposed to the higher dose of DES. By 17 days gestation, coagulative necrosis is common in the decidua basalis, being most severe in those animals receiving 25 micrograms DES/kg. In many placentas the labyrinthine region is absent. The only remaining elements are trophoblast cells, giant cells and glycogen-containing cells. Fetal deaths associated with the lower dose of DES increased with time whereas 100% fetal mortality was associated with the higher dose.

Animals↗
PubMed1980

Replantation--a clinical philosophy.

Although prognosis for the avulsed tooth is guarded, replantation, followed by a brief period of splinting and endodontic therapy, is suggested. Minimal extraoral period, minimal manipulation of the root surface and alveolus, and moist storage for the tooth are identified as factors that minimize resorption. Education of coaches, teachers, and all dentists in the technique of replantation is encouraged.

Follow-Up Studies↗
PubMed1979

Response to cryptorchidism of the testis and epididymis of the opossum (Didelphis virginiana).

Adult male opossums, Didelphis virginiana, were rendered hemicryptorchid for 35 days. The cyrptorchid testis exhibited a significant reduction in weight, while the contralateral testis had a compensatory weight gain compared with testes of untreated animals. Histological changes in the cryptorchid testis included fibrosis of the tunica propria, involution of the seminiferous tubules and an apparent increase in the interstitial tissue. Many seminiferous tubules were empty and germinal cells were absent. Some Sertoli cells persisted, but the cytoplasm was vacuolated. Cryptorchid testes were characterized by mononuclear leucocytic invasion around the tubules, and some eosinophils were observed. Cryptorchidism in the opossum may induce a reaction similar to experimental orchitis.

Animals↗
PubMed1977

Microscopy of the junctional region between human coronal primary and secondary dentine.

The juction between human primary dentine and regular and irregular secondary dentine was examined with a number of different light and electron microscopic techniques. In decalcified material, a narrow band along the innermost surface of the primary dentine stained intensely. The walls of the tubules within the band stained intensely, whereas the tubular walls within the bulk of the primary dentine were not stained. Generally, the walls of the tubules in both types of secondary dentine were also preferentially stained. Although not readily apparent in ground sections, observations of thin sections revealed a dramatic reduction in the number of tubules in regular secondary dentine. Generally, the radiodensity of the intertubular matrix was the same in primary and secondary dentine and the intensely stained band was not seen radiographically. The pulpal ends of the tubules in primary dentine were often occluded with a material having the same radiodensity as peritubular matrix. Both patent and occluded tubules were seen in irregular secondary dentine. Scanning electron microscopy of acid-etched specimens of secondary dentine revealed that some tubules had irregular walls of highly mineralized matrix which was less acid-soluble then the peritubular matrix of primary dentine.

Cuspid↗
PubMed1977

Radioactivity in pituitaries and cerebrums of neonatal rats following [3H]-estradiol administration.

The uptake of radioactivity by the pituitary, cerebrum and muscle of female and male neonatal and prepuberal rats 1 hour after administration of [3H]-estradiol was measured by liquid scintillation. Tissues were homogenized and aqueous, lipid, and protein-nucleoprotein fractions were separated for quantification of radioactivity. No significant sex differences in the radioactivity associated with the pituitary fractions were noted at any of the ages studied.

Animals↗
PubMed1976

The interrelation of LH-RH, ovarian steroids and the adenohypophysis.

In this presentation experimental evidence is reviewed and new information is presented concerning the question of cyclic fluctuations in pituitary responsiveness to endogenous and exogenous hypothalamic-releasing hormones as well as the direct role of steroids in modulating pituitary sensitivity. Experiments are described which show that four-day and five-day cyclic rats respond differently to LH-RH, presumably because of differences in secretion patterns of ovarian steroids. The direct role of these steroids in this process was investigated both from the morphological (light and electron microscopy) and physiological (radioimmunoassay measurement of LH) viewpoint in hypophysectomized rats bearing pituitary homografts. It was found that steroids may directly alter both the morphology and the secretory function of pituitary gonadotrophs. Estradiol was found to depress the amount of LH that was secreted while progesterone was seen to influence primarily the time of LH release following LH-RH injection. Thus, it appears that direct feedback effects of ovarian steroids at the level of the pituitary are important regulators of the sensitivity of pituitary gonadotrophs to the LH- releaseing action of hypothalamic LH-RH.

Animals↗
PubMedDate not supplied

Patient perception of the ischemic arm block.

OBJECTIVE: To investigate patient perception of the ischemic arm block. DESIGN: Retrospective study. SETTING: Fracture clinic of a major city hospital. PATIENTS/PARTICIPANTS: One hundred eighty-one consecutive patients who had an ischemic arm block were mailed a questionnaire. The response rate was 71 percent. RESULTS AND CONCLUSIONS: Forty-two percent of respondents reported significant pain from the tourniquet cuff, and 29 percent reported significant pain during manipulation or within the first hour after releasing the cuff. Statistical analysis showed that cuff pain was independent and not indicative of increased individual sensitivity to pain. Manipulation pain was likewise an independent phenomenon. There was a close relationship between manipulation pain and postprocedure pain. Reported complications were rare. Fourteen percent were dissatisfied with the procedure, which correlated with manipulation pain but not with cuff pain. In conclusion, significant cuff pain during the procedure is common. Manipulation pain is not as common but may lead to dissatisfaction.

Analgesia↗