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Daily treatment of female rats with medroxyprogesterone acetate in aqueous suspension resulted in adrenocortical atrophy. The doses given were those used for oestrus synchronisation. Intramuscular injections of 2-0 mg medroxyprogesterone acetate were used to investigate the atrophic process. Adrenocortical involution was associated with extensive single cell deletion (apoptosis). It is suggested that theses changes were due to suppression of pituitary ACTH secretion. The cytological changes support the concept that single cell death plays an important role in organ remodelling. Biochemical determinations of DNA, RNA, protein and dry matter, and histological examination, did not reveal significant changes in the liver.

Comparisons were made between specimens of intestinal mucosa from three young Friesian steers, killed when showing clinical signs associated with copper deficiency, and three controls that had received supplementary copper. Copper deficiency was associated with marked depiction of cytochrome oxidase in the epithelium of the duodenum, jejunum and ileum, and with partial villus atrophy in the duodenum and jejunum. Enterocytes from the duodenum, jejunum and ileum showed mitochondrial abnormalities ranging from slight swelling to marked localised dilation. Many of the mitochondria not affected by swelling had a distinctly condensed appearance. These changes are discussed in relation to the copper-responsive diarrhoea that affects a proportion of cattle suffering from copper deficiency.

Reproduction in Finnish Landrace × Polled Dorset Horn ewes was accompanied by thickening of the wall of the gall bladder. The thickening was caused by hypertrophy of the epithelium, the presence of cysts, proliferation of blood vessels, glands and fibrous tissue in the lamina propria and hypertrophy of smooth muscle. The changes appeared to be initiated during pregnancy but to persist in a modified and chronic form in post-parturient animals.

Lesions were found in the pancreas of clinically normal cattle of low copper status. In comparison with the pancreas of cattle with normal hepatic copper reserves, the abnormalities were an increase in the dry matter content and reduction in the concentrations of protein and copper in the wet tissue. Cytochrome oxidase activity and protein-to-RNA ratio were also reduced. Histologically, there were defects in acinar basement membranes, splitting and disorganization of acini, cellular atrophy and dissociation, and stromal proliferation. The pancreatic ductular system did not show atrophy or disorganization.

In parous, seasonally-bred Finnish Landrace × Dorset Horn ewes, there was hypertrophy of fibres in the internal oblique abdominal muscle, and a tendency towards an increase in the proportional number, and total cross-sectional surface area, of slow-twitch, oxidative fibres. In older ewes which had been bred intensively, these tendencies were exaggerated and were associated with sub-division and splitting of slow-twitch, oxidative fibres. In the same tissues there was a high incidence of muscle fibre degeneration and necrosis, with replacement of necrotic fibres by fibrous and adipose tissue. It appears that there are cyclical changes of hypertrophy and atrophy, geared to reproductive cycles, and that the processes of degeneration are accelerated during atrophy post-partum. It is likely, but not proven, that in ewes bred intensively the reproductive cycles proceed faster than the cycles of reorganization and repair, so that the extent of pathological change is roughly proportional to the age and productivity of the ewe.

SUMMARY Ewes were kept for the lest 3 months of pregnancy on a diet of grass cubes supplemented with sodium sulphate and ammonium molybdate. The brains of their offspring which were clinically normal were found to be deficient in copper and by histochemical methods a deficiency in cytochrome oxidase was observed in the central nervous system of these lambs. The large motor neurones of the red nucleus and of the ventral horns of grey matter in the spinal cord appeared to be affected most severely. It is suggested that a low content of copper in the brain leads to a deficiency of cytochrome oxidase in the motor neurones and that this is probably the primary lesion in swayback.

A biochemical and histological study was made of the livers of 12 ewes in late pregnancy, 18 post-parturient ewes, and 4 non-breeding ewes. Liver weight did not change significantly during pregnancy, but it increased in relation to the carcase weight, and there was an increase in the concentration of RNA in the tissues. After parturition, there were both hyperplasia and hypertrophy of the parenchymal tissue, and there were significant absolute increases in liver weight, and in the total contents of dry matter, protein, lipid, RNA and DNA. Large seasonal hypertrophic changes occurred also in the livers of non-breeding sheep.

The wall of the alimentary canal of Scottish sheep from 2 hill farms was found to fluctuate in weight and total nitrogen content during pregnancy, but to increase rapidly and progressively in weight and total nitrogen content during lactation. The peak was reached at weaning, after which there was a rapid decline. The protein laid down in the wall of the abomasum, small intestine and caecum from the first third of pregnancy to the height of lactation is negligible when compared with the extra protein requirements for pregnancy and lactation. Histological observations agreed with these data, showing a hypertrophy of the alimentary canal during lactation followed by post-weaning atrophy and, in some instances, degeneration. There were differences in the data obtained from the 2 groups of ewes which we ascribe to the differing husbandry and conditions on the farms from which they came.

SUMMARYThe food intake, the apparent digestibilities of dry matter, and of nitrogen were measured in housed Blackface ewes during late pregnancy, lactation, and after the lambs were weaned. The ewes were slaughtered serially together with non-breeding controls, and the liver, ruminal mucosa, intestines, CNS and carcass were weighed. In association with differing reproductive status marked changes occurred in the content of dry matter and protein in the alimentary organs, but not in the CNS, and the mean weight of DNA in the CNS for all the animals was 130 ± 20 (S.D.) mg.All of the alimentary organs became hypertrophied during lactation, and regressed after weaning. Maximum values for the liver and ruminal mucosa occurred in the sixth week of lactation, and were maintained until weaning. The small intestine reached maximum weight after 4 weeks of lactation.

SUMMARY The distribution of activity of carbonic anhydrase (EC 4.2.1.1) per mg N within the mucosa of the sheep’s abomasum was similar to that of parietal cells. The histochemical localization of activity was mainly in parietal cells and in the walls of blood vessels. Lactation was associated with an increase in weight of stripped abomasal mucosa, with parietal cell hyperplasia and hypertrophy and with an increase in total carbonic anhydrase activity.

Copper deficiency had a differential effect between tissues in the rat pancreas. There was marked loss and atrophy of acinar cells, in which both hypertrophied and degenerating mitochondria were present. Cytochrome oxidase activity in acini was greatly depleted while monoamine oxidase activity was enhanced. Atrophy of acinar cells was accompanied by extensive degeneration of the rough endoplasmic reticulum, and by a failure of zymogen granule synthesis. These changes contrasted strongly with the appearance of non-acinar tissues, in which hypertrophy and degeneration of mitochondria were rarely observed. Islet tissue, pancreatic ducts and blood vessels showed no atrophic changes. Cytochrome oxidase activity in islet tissue, and in the epithelium of the main pancreatic ducts, appeared unaffected.