Free (surface) avian respiratory macrophages (FARMs) were harvested by lavage of the lung^air-sac system of the rock dove, Columba livia. The presence of FARMs in the atria and infundibula was con¢rmed by scanning electron microscopy. The respiratory system has developed several cellular defence lines that include surface macrophages, epithelial, subepithelial and interstitial phagocytes, and pulmonary intravascular macrophages (PIMs). Hence, C. livia appears to have a multiple pulmonary cellular protective armoury. Ultrastructurally, the FARMs and the PIMs were similar to the corresponding cells of mammals. The purported high susceptibility of birds to respiratory diseases, a state that has largely been deduced from morbidities and mortalities of commercial birds, and which has chie£y been attributed to paucity of the FARMs, is not supported by the present observations.
Mucin histochemistry on sections of colon from germ-free and conventional mouse pups showed that all goblet cell mucins were sulphated at birth. During the first two weeks of post natal development, the pattern of mucin production in the ascending colon changed to a distribution of non-sulphated mucins towards the apical zone of the crypts and sulphated sialomucins basally. In conventional animals during the third postnatal week when the complex micro-flora of the colon was becoming established, the typical adult mucin distribution pattern developed, with sulphated mucins now confined to the upper third of the crypt. However, in the absence of a colonizing micro-flora crypt mucins become more and more sulphated until at weaning, most goblet cells of the ascending colon were producing fully or partially sulphated mucins, except for one or two cells at the very base of the crypt.
The relationship between the energy source used by HT-29 cells and their state of differentiation was determined. Short chain fatty acids and acetoacetate were applied to the cells for 9 d, after which the medium was replaced with conventional culture medium for a further 9 d so that the permanence of the changes could be assessed (18 d). Glucose utilization and lactic acid, acetoacetate, and beta-hydroxybutyrate production by the cells were determined. Differentiation was assessed by the presence of the enzymes sucrase-isomaltase and carbonic anhydrase 1, as well as morphological changes of the cells. By tracing carbon from acetate, propionate, and butyrate through the cells, it was found that the carbon from the short-chain fatty acids was fluxed into acetoacetate. Significant amounts of acetoacetate were released by the propionate-treated culture after 9 d and the acetate-, propionate-, valerate-, and caproate-treated cultures after 18 d. A significant positive correlation was found between acetoacetate synthesis and differentiation. Acetoacetate applied to HT-29 cells also induced their differentiation. The acetate-, butyrate-, valerate-, isovalerate-, and caproate-treated cells underwent terminal differentiation, while the propionate- and isocaproate-treated cultures underwent programming events. We, therefore, conclude that HT-29 cells utilize short chain fatty acids in preference to glucose, metabolize these to ketones, thereby raising the energy state and effecting the observed morphological and functional changes in the cells.
The vaginal bacterial flora of MFl mice was studied using bacteriological culturing techniques, light microscopy and scanning electron microscopy, and results related to stage in oestrous cycle as determined by cytological smears. Total viable bacterial numbers at metoestrus and dioestrus were lower than at oestrus and proestrus. Bacteria of the genera Streptococcus, Lactobacillus, Corynebacterium, Staphylococcus and Actinomyces were consistently isolated at all stages of the cycle, although at proestrus and oestrus the Streptococcus and Lactobacillus mainly contributed to the increase in bacterial numbers. These results are associated with vaginal cellular changes at various stages of the oestrous cycle. Metabolic end-products produced by the vaginal bacterial flora may contribute in signalling the sexual status of the mice to receptive males.
Micro-anatomical changes in colonic and caecal epithelia of infant rats between birth and weaning appear to be the outcome of the effects of bacterial colonization, superimposed on the natural postnatal ontogeny of the mucous membranes. Conventional rat pups between 15 and 22 days of age showed development of subepithelial spaces in both caecum and colon, rupture of the overlying epithelium and loss of whole enterocyte plaques. Antibiotic-treated animals retained the large-bowel mucosal morphology of the 10-day-old rat, without any of the lesions described in conventional infants. Mucosal lesions were typical of ischaemic damage, possibly triggered by lumen anoxia during colonization.
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