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Biomedical subjects

J Knowles

Publications and source records attributed to J Knowles.

62 records · Page 4Linked to original sources
PubMed1978

Effect of oestrogen on the pituitary gland of male Syrian hamsters. I. Electron microscope studies of pars intermedia.

The ultrastructure of the pars intermedia of normal and oestrogen-treated male Syrian hamsters is described. 3 types of cell were observed in normal gland, namely, 2 types of "light" cell and a "dark" cell. Light cells were regular in shape with round or oval nuclei and could be divided into type 1 and 2 by the size of their granules 200 to 250 nm in type 1 and 100 to 150 nm in type 2. Dark cells were fewer in number, irregular in outline with highly-indented chromatin-rich nuclei and occasional secretory granules in the Golgi area. Treatment for 6 weeks with diethylstibestrol (DES) 0.6 mg in 0.2 ml distilled water subcutaneously 3 times per week failed to induce recognisable change in the pars intermedia although after 12 weeks treatment cytoplasmic changes were observed. From that time until the experiment ended after 30 weeks of treatment progressive changes indicative of enhanced synthesis of hormone were present, greater cytoplasmic volume, hypertrophy of the Golgi apparatus, marked development of endoplasmic reticulum and ribosomes, increased numbers of secretory granules and the presence of granules within granules.

Animals↗
PubMed1976

Experimental contribution to the pathogenesis of spina bifida.

Reopening of the central canal in 3-day-old chick embryos results in the development of a typical myeloschisis within 5 min. Focal continuity between the ectoderm and neural tissue at the site of experimentally induced spina bifida (SB) may be achieved in 2 hr and increases in consecutive hours. In 24 hr a secondary neuro-ectodermal junction at the site of SB is fully formed and can be misinterpreted as evidence of a failure of the neural tube to close. Therefore the continuity between ectoderm and neural tube to close. The detachment of the notochord from the open portion of the spinal cord is a secondary phenomenon.

Animals↗