Effect of Prolonged Thyroid Administration on Aged Male Rats

Abstract

TISSUES from nineteen aged unaltered male Holtzman strain rats (average body-weight 374.4 gm.) which had been administered orally 0.18 mgm. of ‘Proloid’ daily (Warner-Chilcott purified thyroid extract) from the age of 14 months to death at 24 months were compared anatomically with those of ten control animals (average body-weight 352.7 gm.) to note any gross or histological anatomical variations induced by the drug. The tissues were fixed immediately following death in buffered 10 per cent formalin and processed routinely by the paraffin method. The tissues examined were testis (including epididymis), kidney, liver, pancreas, buccal gland, seminal vesicle, aorta (both thoracic and abdominal), superior and inferior vena cava, heart, spleen, pituitary, adrenal, prostate and thyroid glands, costal cartilage with surrounding skeletal muscle, diaphragm, trachea, lung, levator ani muscle, abdominal skin and all levels of the gastrointestinal tract including upper and lower œsophagus, fundic and pyloric stomach, duodenum, jejunum, upper and lower ileum, cæcum, ascending, transverse and descending colon and rectum. The sections were stained for examination by the following methods^1–3 : (1) hæmotoxylin and eosin; (2) the Goldner connective tissue stain; (3) the McMannus periodic acid–Schiff technique ; (4) the catalysed lead tetraacetate–Schiff technique; (5) the Rinehart–Abu'l–Haj modification of the Hale dialysed iron procedure for acid polysaccharides; (6) the periodic acid–Foot reticular connective tissue stain; (7) the orcein procedure for elastic tissues. It was felt that these methods, when used in comparison, would adequately disclose any possible histochemical variations from the normal.