Effect of vitamin A nutritional status on the growth of oestrogen-primed chick oviduct.

Growth and development of the oestrogen-primed oviduct of immature chicks in terms of weight, length, total protein, total RNA, total DNA and total phospholipids are markedly arrested on deprivation of vitamin A; supplementation with retinyl acetate reversed the effect of the deficiency almost fully, whereas retinoic acid was only partly effective.     

Effect of estrogen on angiotensin converting enzyme in immature quail oviduct.

Effect of oestradiol was studied on the angiotensin converting enzyme (ACE)--a component of renin angiotensin system, in oviduct of immature quails of 15 days of age. ACE was studied in whole oviduct, magnum, shell gland and the glandular epithelium of magnum and shell gland. It was found that whole oviduct had a significantly higher level of ACE in control than those treated with exogenous estrogen at three dose levels (200, 400 or 600 micrograms). ACE contents of whole muscle and glandular epithelium did not differ but magnum had higher ACE level than the shell gland. Results are explained on the basis of functional role of oviductal parts.     

Periodic histopathological and ultrastructural changes of excess vitamin A on oral carcinogenesis

In this study initially a precancerous condition, leukoplakia, was develop at 6 weeks treatment of DMBA whereas in the animals treated both DMBA + Vit. A, leukoplakia was seen at 10 weeks followed by papilloma or nodules at 12 weeks. Tumours induced by DMBA were more in number than DMBA + Vit. A treated tumours. The histological and ultrastructural changes were enhanced and prominent in DMBA treated animals at 12 weeks, where as these changes were considerably less in animals treated with DMBA + vit. A at 12 weeks.     

Biochemical and ultrastructural hepatic changes during vitamin B12 deficiency in animals and man.

Vitamin B12 deficiency has been shown to result in an increase in content and activity of the hepatic cytosolic enzymes of fatty acid synthesis. The present study demonstrated that ATP citrate lyase, an enzyme whose activity has been positively correlated with rates of fatty acid biosynthesis, also increased in the livers of B12-deficient animals. Total and specific activity of hepatic citrate synthase, an enzyme whose activity is unaffected by a variety of dietary and hormonal changes, also was found to be increased in the B12-deprived state. By contrast, the activity of hepatic succinate-cytochrome c reductase, a portion of a multicomponent enzyme complex synthesized in part within the mitochondria, was unchanged in B12 deficiency. Vitamin B12 deprivation resulted in an increase in hepatic mitochondrial cristae membranes in both animals and man. Histochemical and chemical analysis demonstrated increased glycogen in the liver cells from B12-deficient animals and man. Thus, in the livers from vitamin B12-deficient animals there is an increased activity of the otherwise highly constant Krebs cycle enzyme citrate synthase, and in both animals and man there are increased mitochondrial cristae membranes.     

Stereological analysis of ultrastructural changes of surrounding tissues to neuroectoderm during chick embryo neurulation

The cytometric evolution of different subcellular components in the epiblast and the mesoderm of chick embryo during neurulation has been studied with stereological methods. The coefficient of cellular form (CFc) has specific values for each type, the epiblast having a mean CFc of 0.474, while the mesoderm, which has ellipsoidal cells, has a mean CFc of 0.643. The nucleus does not show any change of its coefficient of form although its surface density increases significantly. The proportion of mitochondria, present in the cells of each embryonic layer, remains constant during the 4 stages, being higher in the mesoderm cells (epiblast 3.6%; mesoderm 4.3%). The epiblast cells show a stable vitelline reserve, though the relative proportions of lipid bodies and yolk droplets vary: the volume density of yolk droplets increases from stage 5 (3.1%) to stage 8 (7.7%), while the lipid bodies diminish from 7 to 3.6% during this period. The mesoderm cells undergo a remarkable loss of vitelline volume during the same period. The rough endoplasmic reticulum of each cellular type has a remarkable length density increase, the significance of which is discussed in relation to production of extracellular matrix.     

Elevated cyclic GMP concentrations during estrogen induced differentiation of the chick oviduct.

The levels of cGMP and cAMP in the chick oviduct were evaluated during estrogen-induced differentiation and growth at two different stages of development. In the differentiating oviduct cGMP levels were found to change markedly. Tissue concentrations were elevated 35-fold by 2 hr after primary stimulation and about 3-fold at later time intervals. In contrast, constant levels of cGMP were observed during growth of the differentiated oviduct after secondary stimulation. cAMP concentrations were not or very little changed during differentiations and secondary stimulation of the oviduct. Our data suggest that elevated cGMP levels represent an active signal for the differentiative response of the chick oviduct to estrogens.     

Effect of vitamin D and plasma calcium upon proteoglycan size in chick growth cartilage.

Proteoglycan subunit isolated from the growth cartilage of rachitic chicks is of much smaller size than the corresponding preparation from vitamin D-treated chicks. The size change can be related to differences in plasma calcium concentration and not to the vitamin D status of the chicks.     

Morphometric and ultrastructural features of the mare oviduct epithelium during oestrus

Morphometric, scanning electron microscopy (SEM) and transmission electron microscopy (TEM) investigations have displayed regional differences in the mare oviductal epithelium. The entire mucosa of the oviduct was lined with a pseudostratified epithelium, which consisted of two distinct cell types, ciliated and non-ciliated. Ciliated cells were predominant in the three different segments of the oviduct and their percentage increased from fimbriae to ampulla and significantly decreased in the isthmus. SEM revealed in the infundibulum finger-like mucosal folds, some of them interconnected, in the ampulla numerous and elaborated branched folds of the mucosa, whereas the isthmus displayed a narrow lumen, short and non-branched mucosal folds. In the ampulla and isthmus the majority of non-ciliated cells showed apical blebs provided or not of short microvilli. TEM displayed different ultrastructural features of ciliated and non-ciliated cells along the oviduct. Isthmus ciliated cells presented a more electron-dense cytoplasm than in infundibulum and ampulla cells and its cilia were enclosed in an amorphous matrix. The non-ciliated cells of infundibulum did not contain secretory granules but some apical endocytic vesicles and microvilli coated by a well developed glycocalyx. Non-ciliated cells of ampulla and isthmus contained secretory granules. Apical protrusions of ampulla displayed two types of secretory granules as well as occasional electron-lucent vesicles. Isthmus non-ciliated cells showed either electron-lucent or electron-dense cytoplasm and not all contained apical protrusions. The electron-dense non-ciliated cells displayed microvilli coated with a well developed glycocalyx. Three types of granules were observed in the isthmus non-ciliated cells. The regional differences observed along the epithelium lining the mare oviduct suggest that the epithelium of the each segment is involved in the production of a distinctive microenvironment with a unique biochemical milieu related to its functional role.     

Fractionation of chick oviduct chromatin. Nuclease-resistant deoxyribonucleic acid.

Chromatin isolated from several chick tissues was treated with micrococcal nuclease. A limited degree of tissue specificity of chromatin DNA resistance to nuclease digestion was observed. No difference in the extent of nuclease resistance of chromatin DNA was detected during oestrogen-induced oviduct differentiation. This suggested that the amount of non-histone chromosomal protein does not play an important role in the sensitivity of chromatin DNA to nuclease digestion. Studies of nuclease resistance of chromatin DNA after dissociation and reconstitution of chromatin proteins and ethanol extraction of chromatin indicate that the histones protect the DNA from nuclease attack. Slow thermal denaturation of nuclease-resistant DNA suggests that the protected DNA sequences may be (A+T)-rich, and the (G+C)-rich satellites present in total chick DNA are sensitive to nuclease.     

Effect of vitamin D deficiency on bone formation in the chick.

1. The process of diaphyseal bone formation can be investigated by studying the rate of incorporation of radioactive precursors, administered in vivo into bone fractions of increasing density. 2. In the 4-week-old vitamin D-treated chick most of the osteoid becomes calcified within 12h and almost all within 2 days. The low-density calcified phase that is formed is converted into a higher density form and within 7 days the greater proportion of the calcified tissue is in the higher density form. 3. In the vitamin D-deficient chick of similar age the rate of calcification of osteoid is decreased, as is the rate of conversion into the higher density phase with the resultant accumulation of the lower density calcified form. 4. The higher density phase probably corresponds to hydroxyapatite and the lower density one to the ACP-pase described by Termine & Posner [(1967) Calcif. Tissue Res. 1, 8--23]. 5. The disorder in the process of calcification seems to be unrelated to the alteration in blood Ca2+ and phosphate concentrations, but related to the presence or absence of cholecalciferol.