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Biomedical subjects

R G Harrison

Publications and source records attributed to R G Harrison.

At least 55 records · Page 3Linked to original sources
PubMed1982

A reexamination of rat ductuli efferentes.

In 33 testes from a random selection of rats a 10% suspension of India ink in normal saline was introduced through the rete testis into the emergent ductuli efferentes. Low-power microscopy and microradiography confirmed the individually independent origin of each ductule. Five ductules were isolated in each of 17 testes, 4 ductules in 6, 6 ductules in 8, and in 2 testes, 7 and 9 ductules, respectively. In six animals minor variations existed as between the right and left testes +/- 1 in 4 and +/- 2 in 2. It is necessary to exercise great caution in the interpretation of results of experimental work on alteration of the ductuli, because of variability between colonies and within strains of rats.

Animals↗
PubMed1982

Impairment of rat spermatogenesis following unilateral experimental ischemia.

When one testis in a rat is rendered ischemic, histologic damage occurs in the contralateral testis, which can be explained on immunologic grounds. An increase in the quantity of a naturally circulating cytotoxic antitestis antibody or an alteration in the specificity of this antibody was observed via cytotoxic antibody tests. Immunocytochemical techniques further demonstrated this phenomenon, showing binding of fluorescein-labeled antibody to sections of normal control testis or to sections of contralateral testis. It appeared that the ischemic testis presented altered ischemic cells or normal cells to the immune system as its blood-testis barrier was broken down. It is suggested that to leave a necrotic testis within the scrotum following prolonged torsion of the testis in the human may be a reason for subfertility or infertility in this type of condition, and a similar result may occur following unilateral testicular damage caused by varicocele or orchitis.

Animals↗
PubMed1982

The pattern of the lymphatic drainage of the rat epididymis.

The rat epididymis is drained by separate lymphatics which emerge from the head, the body and the tail and join to form a single vessel which drains into the main testicular trunk. The pattern of lymphatic drainage is very similar to that of the arterial blood supply. There are anastomoses at various levels between lymphatics draining the testis and the epididymis. A final common pathway of the lymph drainage of the testis and epididymis towards the para-aortic nodes is described.

Animals↗
PubMed1981

Mechanism of damage to the contralateral testis in rats with an ischaemic testis.

A degenerating ischaemic rat testis produces damage to its contralateral testis. When ischaemic testes were grafted or injected as a homogenate for a week into littermate rats there was considerable damage to host testes. This damage was caused by an immunological response, demonstrated as an increase in cytotoxicity of host serum which increased immunofluorescence, particularly of the membrana propria, which had become thickened. Manipulation of the testis and its blood supply was sufficient to cause spermatogenic damage and initiate an immunological response. These results indicate that viable early torted testes must have their torsion corrected and be anchored in the scrotum, but if the testis is ischaemic and non-viable it should be removed to avoid damage to the contralateral testis.

Animals↗
PubMed1979

Antianaphylactic agents. 1. 2-(Acylamino)oxazoles.

The synthesis and biological properties of 35 2-(acylamino)oxazoles are described. The majority of the compounds inhibit the release of slow-reacting substance of anaphylaxis (SRS-A) in vitro from sensitized guinea pig chopped lung. In addition, several of the compounds inhibited the release of SRS-A from passively sensitized human chopped lung and protected guinea pigs from the effects of anaphylaxis in a modified Herxheimer test.

Anaphylaxis↗
PubMed1978

The effect of interruption of lymphatic drainage from the rat testis.

Forty-two mature albino rats were subjected to the ligation of selected lymphatic vessels close to, and at a distance from, the testis. At periods from 3 days to 1 year both testes were studied at their equatorial level in order to determine histological changes. The operated testes showed a mild degree of damage 3 days after operation and moderate damage at 7 days, while damage of a severe degree increased to a maximum over a postoperative period of 90 days. One-hundred-and-eighty days after operation a few tubules presented the typical appearance of spermatogenic destruction. After 1 year recovery is virtually complete. Changes in the contralateral testis indicate an immune response to the damage induced on the ipsilateral side by the experimental interruption of selected lymph vessels, where interstitial oedema was confined sectorially to the medial half of the testis. In the contralateral testis, oedema was predictably diffuse throughout; the distribution of tubular deformities and the degree of cellular damage were less well marked and 1 year after operation the testis had almost completely recovered. Tubular deformities and cellular changes in the germinal epithelium are primarily dependent on interference with the lymph flow and are not secondary to ischaemia.

Animals↗
PubMed1978

The pattern of lymphatic drainage of the rat testis.

The basic pattern of the lymphatic drainage of the testis is described in the mature albino rat following studies in vivo and the examination of dissected specimens in vitro. Microlymphography was undertaken using various contrast media. Three groups of lymphatics leave the surface of the testis--superior, medial and inferior, from the upper pole, from the mediastinum and from the lower pole respectively.

Animals↗
PubMed1976

Water flux through porcine aortic tissue due to a hydrostatic pressure gradient.

The water flux through preparations of porcine aorta has been investigated. After an initial unsteady period a stable flux of approximately 2 mul/cm2-h was reached and this flux rate remained constant for several hours. Under the experimental conditions which were maintained (110 mm Hg pressure drop across a 2 mm thick section of tissue) this total flux corresponds to a hydraulic conductivity of less than or equal to 7.0 X 10(-13) cm4/dyne-sec. Since these data were obtained in tissue samples where the endothelial layer was not intact, they represent values which are in fact larger than the actual in vivo condition where the endothelial barrier would serve as an additional resistance. Thus, they demonstrate that the transmural flux of water across the aorta wall in vitro due to a pressure gradient is extremely small and, therefore, that other mass transfer mechanisms may be significant.

Animals↗
PubMed1976

Extracellular space of swine aorta measured with [14C]inulin and [14C]sucrose.

Measurements of the extracellular space (ECS) of the isolated swine thoracic aorta were performed with both [14C]inulin and transient measurements and appeared to have better access to available tissue water than the [14C]sucrose gave more consistent results in available tissue water than the [14C]inulin. With [14C]sucrose as the tracer, no significant difference in the ECS was found when the tissue was incubated for 1.5 h in the presence of oxygen and glucose as compared to an incubation in which both oxygen and glucose were absent. However, the ion contents were markedly altered by this change in incubation medium. When oxygen and glucose were present tissue K+ was significantly higher and tissue Na+ was significantly lower than when these metabolites were deleted from the medium. Thus, significant alteration in ion content did not lead to substantial cell damage or bursting.

Animals↗
PubMed1976

A presomite human embryo of Horizon VII.

A presomite embryo of Horizon VII aged approximately 18 days is described and illustrated. It is compared with some other embryos of a similar age, and a considerable variation of histological characteristics within the same Horizon is noted.

Chorion↗
PubMed1976

The ultrastructural relationships between Sertoli cells and spermatogenic cells in the rat.

The cell-to-cell junctions between Sertoli cells and between Sertoli cells and spermatogenic cells have been described and illustrated in the rat seminiferous tubule. The most important junction is a zonula (or macula) adherens which exists between Sertoli cells on the one hand and spermatogonia on the other. No such junctions are observable between Sertoli cells and late spermatids in the Golgi, acrosomal or cap phases. Mitochondria in these spermatids are the 'energized' type and are lined up close to the inner aspect of the cell membrane; whereas in all other spermatogenic cells they are 'non-energized' and randomly orientated. Almost all the ultrastructural characteristics of steroid hormone-secreting cells have been observed in Sertoli cells. The functional significance of these findings is discussed.

Animals↗
PubMed1975

An analysis of the effect of ischaemia on testicular ultrastructure.

Permanent ischaemia of the rat testis results in the formation of fusion multinucleate cells and macrophages from cells of the innermost cellular layer, in the ischaemic testis. The macrophages are replaced by fibroblasts after 25 days of ischaemia. Similar changes are visible in the contralateral testis which also demonstrates the evolution of multinucleate spermatids by karyokinesis without cytokinesis. Binucleate spermatids and double-headed spermatozoa have only one acrosome, and spermatozoa with two middle pieces are enveloped by a single cytoplasm. The sequential ultrastructural changes following ischaemia are described and it is suggested that cells of the inner cellular layer can alter their characteristics according to demand.

Animals↗
PubMed1975

The ultrastructure of the adrenal cortex of the Mongolian gerbil (M. unguiculatus).

Ultrastructurally, the adrenal cortex of the Mongolian gerbil can be divided into two main regions and one narrow interposed border zone. The outer region corresponds to the zona glomerulosa and zona fasciculata of the rat adrenal cortex, whereas the inner region corresponds to the rat zona reticularis. The mitochondria are variable in shape, size and internal structure but generally lamelliform or tubulo-vesicular with a dense matrix in the outer region and plate-like and tubular in the inner region. Some of the mitochondria in the border region are of the polylaminar membranous type. The endoplasmic reticulum is abundant and smooth in the outer region but less prominent in the inner regions, where it is both smooth and rough. The concentric whorled membranes of rough endoplasmic reticulum are a characteristic feature of the border zone. Lipid vacuoles are abundant in the outer region. Lysosomes are numerous in the inner region and tend to form groups of 4 or 5. Aminoglutethimide causes a less conspicuous alteration in the adrenal cortex of the Mongolian gerbil than in the rat. The main alterations consist of a profound increase of lipid and lysosomes, a decrease in the number of SER profiles, and complete disappearance of the whorled membranes of RER.

Adrenal Cortex↗