Three approaches were made to study the interrelations between thyroid function and vitamin A in avian metabolism. These were a histological assessment of the activity of the thyroid gland as it is affected by hypervitaminosis A, the effect of hypervitaminosis A on the incubation time of eggs injected with different levels of vitamin A alcohol and palmitate, and finally the effects of hypervitaminosis A on thyroidal uptake and release of radioiodine by chickens.
These studies yielded the following observations. CI) Histological -measurements indicated that dietary hypervitaminosis A can depress the secretion of thyroid stimulating hormone. (2) The effect of hypervitaminosis A on thyroid activity as affected by environmental temperature. (3) Vitamin A palmitate and alcohol prolong incubation time. The alcohol form has, in addition, an adverse effect on embryonic development which is manifested in hemorrhaging and malformation of the embryo. (4) Vitamin A in excess may either depress or stimulate thyroidal uptake of radioiodine depending upon an unidentified component of the environment. (5) Vitamin A in excess affects the endocrine system. This is indicated by an increase in size of the thyroid and adrenal glands and a decrease in size of combs and testes. / Land and Food Systems, Faculty of / Graduate
| Identifer | oai:union.ndltd.org:UBC/oai:circle.library.ubc.ca:2429/34280 |
| Date | January 1971 |
| Creators | Coates, Viona |
| Publisher | University of British Columbia |
| Source Sets | University of British Columbia |
| Language | English |
| Detected Language | English |
| Type | Text, Thesis/Dissertation |
| Rights | For non-commercial purposes only, such as research, private study and education. Additional conditions apply, see Terms of Use https://open.library.ubc.ca/terms_of_use. |
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