Use of carbon labeling to demonstrate the role of blood monocytes as precursors of the 'ameboid cells' present in the corpus callosum of postnatal rats.

Cells with features suggestive of ameboid motion and phagocytic properties are observed in the rat corpus callosum during the first few days of life. These cells, hereafter referred to as 'ameboid cells', have been investigated in several ways. An electron microscopic study of the corpus callosum in 5- to 7-day-old rats indicated that most 'ameboid cells' were typical macrophages, but some displayed features of monocytes, while others appeared to be transitional between the two types.

Fine structural study of postcastrational adrenocortical carcinomas in female CE-mice.

Postcastrational adrenocortical carcinomas in the CE/Ki inbred strains of mice and the adrenals of noncastrated CE/Ki mice were studied using light and electron microscopic techniques. Most of the tumors appeared as large nodules of cells separated by septae comprised of collagen and blood sinusoids. The majority of tumor cells (Type 1) showed few or no lipid droplets (sudanophobic), polymorphic hyperchromatic nuclei, lack of SER, abundant RER and free ribosomes, prominent Golgi complexes, and few mitochondria with scant internal membranes.

Fine structural and biochemical effects of aminoglutethimide and o,p'-DDD on rat adrenocortical carcinoma 494 and adrenals.

Rats bearing adrenocortical carcinoma 494 were injected daily for 7, 14, or 21 days with aminoglutethimide (AG) or o,p'-DDD. Reversibility of these steroidogenic inhibitors was determined by injecting other animals for either 14 or 21 days and sacrificing them 14 days later. While the drugs had little effect on body or tumor growth, plasma corticosterone levels were reduced a maximum of 88% in normal and 95% in tumor-bearing rats during AG chemotherapy.

Phenobarbital-induced alterations of the rat adrenal cortex.

To determine the morpholic changes in adrenocortices induced by chronic phenobarbital therapy, the male rats were orally administered the drug daily for varying periods up to three months. Fine structural changes attributable to the drug included mitochrondrial pleomorphism and cavitation, loss of cholesterol ester clefts, reorganization of intracellular lipid, hypertrophy of the agranular endoplasmic reticulum and a juxtapositioning of the agranular endoplasmic reticulum, mitochondria and lipid droplets--all suggestive of an actively secreting cortex. The digitonin-glutaraldehyde reaction suggested an active translocation of free cholesterol from lipid droplets to the mitochondria and agranular endoplasmic reticulum following phenobarbital treatment.

Effect of acute and chronic misonidazole administration on peripheral-nerve electrophysiology in mice.

I.p. administration at several dose levels over periods of up to 12 weeks, or continuous i.

Diazepam receptor: specific nuclear binding of [3H]flunitrazepam.

Autoradiographic localization of [3H]flunitrazepam in nuclei of the rat cerebral cortex was further confirmed by biochemical analysis of specific nuclear binding. Highly purified rat cerebral cortex nuclei were shown to bind [3H]flunitrazepam specifically. The Kd(app) for nuclear binding was 28 nM for the nuclei compared with a Kd(app) of 1.

Morphological and functional characteristics of cells infiltrating and destroying tumor multicellular spheroids in vivo.

EMT6 mammary sarcoma cells were grown in vitro as multicellular spheroids to model for the heterogeneity of microenvironments and structural changes which develop in many tumors, including micrometastases. Spheroids of 700-900 micron diameter were implanted into and recovered at different times from the peritoneal cavities of sensitized or nonsensitized allogeneic and syngeneic mice. The colony forming efficiency of spheroid tumor cells recovered at 24 and 48 h from sensitized allogeneic mice was markedly decreased as compared with those from nonsensitized allogeneic or syngeneic animals.

Hematologic changes in the rat during and after exposure to carbon monoxide.

Rats were continuously exposed to 500 p.p.m.

Biochemical, morphologic and physiologic changes in the adrenal glands of rats chronically treated with phenobarbital.

Biochemical and ultrastructural changes in the adrenal glands of rats were observed after long-term phenobarbital treatment. At the fine structural level, the parenchymal cells of the phenobarbital-treated rats resembled cortical cells that had been stimulated by adrenocorticotropin. A significant finding was the presence of very large hollow mitochondria characterized by loss of vesicles and cristae with retention of the double outer membrane.

Changes in the adrenal cortex of the rat after chronic administration of the steroidogenic inhibitor U-8113.

In concert with studies of the effects of various pharmacologic inhibitors of corticosteroidogenesis on adrenocortical morphology, U-8113, an analog of amphenone B, was administered daily to Sprague-Dawley rats for 7, 14, 21 or 30 day. The primary morphological responses involved increases in adrenal weight, width of zona fasciculata, width of zona reticularis, intracellular lipids, mitochondrial size, mitochondrial vacuolation and crystalline-like inclusions, small coated vesicles, lysosomes, autophagic vacuoles and cholesterol ester clefts. In particular, the increases in lysosomes, coated vesicles and autophagic vacuoles containing morphologically altered mitochondria were considered reflective of mechanisms designed to maintain cellular integrity amidst functional impairment.

Fine structural studies of radiation-resistant human squamous cell carcinomas.

Squamous cell carcinomas of the oral cavity are relatively common lesions, and often can be controlled by radiation therapy. Recently, a series of these tumors has been encountered which did not respond positively to irradiation, necessitating subsequent extensive surgery. This report describes some fine structural changes which were observed in squamous cell carcinomas following exposure to x-irradiation.

Rat adrenocortical carcinoma 494: an integrated structural, stereological, and biochemical analysis.

Snell adrenocortical tumor 494 was implanted into male Sprague-Dawley rats and recovered 7, 14, 21, 28 or 35 days following initial detection by palpation (7-10 days following transplantation). Electron microscopic, stereological and biochemical analyses of the tumor were compared to adrenals of normal animals to serve as a baseline for further studies of the effects of chemotherapeutic agents on tumor cells. Tumor cells possessed oval or elongated mitochondrial profiles with tubular cristae, one or two very large (greater than 5 micrometer) lipid droplets, abundant ribosomes and coated vesicles, and sparse rough and smooth endoplasmic reticulum.

The perinatal rat: body weight, hematocrit and regional changes in heart weight and lactate dehydrogenase isozyme composition and activity.

Body weight (BW), hematocrit (Hct), heart weight (HW) and cardiac lactate dehydrogenase (LDH) activity and isozyme pattern were studied in the perinatal rat. BW increased linearly, from 5 days before birth till 10 days after birth, while Hct increased from 30 to 34% within 1 day of birth. HW increased in step with BW.

Hematologic responses to carbon monoxide and altitude: a comparative study.

Groups of 40- and 90-day-old rats were exposed to 500 ppm CO (HbCO=31-43%) and simulated altitude (15,000 ft). Resulting hematologic changes were monitored after 1 day, 1 wk, 3-4 wk, and 9-11 wk of exposure. The two treatments resulted in similar changes in hemoglobin (Hb) and hematocrit ratio (Hct) in the young rats, while in the older group there were several small, but significant differences in these parameters.