- Email: [email protected]
Embryonic Response to Iodine-1311
96
P. N.
DUA AND
seconds was plotted against the log of vitamin K level, mcg./kg. of the diet (Fig. 1). The ratio of activity of MSBC to MPB was found to be 1:1.9 with 95% confidence limits between 1:1.6 and 1:2.3. These ratios are higher than the calculated ratio of 1:1.37 of MSBC and MPB, based on their actual menadione content. These results are essentially similar to those reported by Griminger (1965).
A study was conducted with chicks to compare the relative vitamin K activity of a new water soluble menadione analogue, menadione dimethylpyrimidinol bisulfite (MPB, containing 45.5% menadione) with that of menadione sodium bisulfite complex (MSBC, containing 32.8% menadione). The ratio of activity of MSBC to MPB on an equal weight basis was found by a parallel line bioassay procedure to be 1:1.9. ACKNOWLEDGMENTS
The authors wish to express their thanks to Dr. Walter J. Drapala for statistical ad-
DAY
vice, and Mrs. Geneva assistance. This work part by a grant-in-aid cal Corporation, Valley
Ray for laboratory was supported in from HeterochemiStream, New York,
REFERENCES Davies, O. L., 1958. Statistical Methods in Research and Production. Hafner Publishing Company, New York. Dua, P. N., and E. J. Day, 1965. High levels of menadione dimethylpyrimidinol bisulfite in broiler rations. Poultry Sci. 44: 1140-1141. Frost, D. V., H. S. Perdue and H. C. Spruth, 1956. Vitamin K activity of menadione sodium bisulfite in chickens. J. Nutrition, 59: 181-196. Griminger, P., 1965. Relative vitamin K potency of two water-soluble menadione analogues. Poultry Sci. 44: 210-213. Nelson, T. S., and L. C. Norris, 1960. Studies on the vitamin K requirement of the chick. 1. Requirements of the chick for vitamin Ki, menadione and menadione sodium bisulfite. J. Nutrition, 72: 137-144. Perdue, H. S., H. C. Spruth and D. V. Frost, 1957. Comparison of vitamin K activities of vitamin Ki and Klotogen (Menadione sodium bisulfite complex). Poultry Sci. 36: 633-635. Steel, R. G. D., and J. H. Torrie, 1960. Principles and Procedures of Statistics. McGraw-Hill Book Company, Inc., New York.
Embryonic Response to Iodme-1311 FRANK
R.
MRAZ
Agricultural Research Laboratory of The University of Tennessee, Oak Ridge, Tennessee1 (Received for publication July 2, 1965)
ODINE-131 with a half life of 8.05 days; has at least 4 beta emissions varying; from 0.08 to 0.72 mev. Eighty percent off each emission is composed of a 0.61 mevi beta and a 0.37 mev gamma emission. Io--
I
1
This manuscript is published with the permission of the Director of the University of Tennessee Agricultural Experiment Station, Knoxville. 2 Operated by the Tennessee Agricultural Experiment Station for the U.S. Atomic Energy Commission under Contract No. AT-40-1-GEN242.
dine concentrates in the thyroid, where, if radioactive, it can irradiate this tssue. This specificity enables small amounts of I 131 to produce serious damage to the thyroid. As little as 6 mc. I1S1 per 100 gm. of body weight injected into chicks was shown to completely destroy their thyroids (Winchester et al, 1949; Winchester and Davis, 1952). Normal growth rates were restored by injection of 1 to 12 gamma of thyroxine per 100 gm. of body weight. Mellen and Wentworth (1962) pretreated
Downloaded from http://ps.oxfordjournals.org/ at Northern Arizona University on June 2, 2015
SUMMARY
E. J.
97
EMBRYONIC RESPONSE TO IODINE-131
their birds with a low-iodine diet and thiouracil to reduce the I 131 necessary for thyroid destruction to 1.5 mc. per 100 gm. A series of experiments was conducted to determine the effect of I131 injections on embryos, to ascertain the lowest level at which damage to the embryo would occur, and to estimate the levels administered to the hen that would result in sufficient I 131 in the egg to harm the embryo.
of I131 injected into eggs (12 eggs per treatment) Days of incubation 8th Hatched
embryos
12 th Hatched
16th
embryos
12 12 12 7 0 0 0 0
5 12 12 12 12
Hatched
11 12 10 12 0 1 0 0 0
embryos
1 12 11 12 12 12
* Number of live embryos remaining in eggs that did not hatch.
The chicks that hatched were fed a commercial chick diet and water ad libitum. At 4 weeks of age the chicks were weighed and then intramuscularly injected with 25 (AC. carrier-free I 131 and sacrificed 48 hours later. Thyroids were removed and their I 131 contents determined. To assess the levels necessary in a single dose to the hen to damage the thyroids of chicks hatched from her eggs, 6 to 8 hens were intramuscularly injected with 0.5, 1, 2 or 4 mc. carrier-free I131. The I 131 contents of a total of 375 of their eggs were determined immediately prior to incubation by placing them over a well-type scintillation detector that had its upper shielding removed. The nutritional regime of the resulting chicks was similar to the present experiment. Intramuscular injection of I 131 occurred at 4 weeks of age and the chicks were sacrificed 24 hours later. Thyroids were removed, weighed and their content determined. RESULTS
Hatchability (Table 1) was reduced in embryos injected with I 131 levels of 25, 50, and 100 [i.c. or higher at 8, 12, and 16 days of incubation, respectively. All the remaining eggs were broken open at 22 days of incubation and were found to have live embryos with unabsorbed yolk sacs similar to those found in 18- or 19-day em-
Downloaded from http://ps.oxfordjournals.org/ at Northern Arizona University on June 2, 2015
EXPERIMENTAL Initially, 12 eggs were injected with 5, 25, 50, 100, or 150 [xc. of carrier-free I 131 as sodium iodide in basic sodium sulfite solution at 8, 12, or 16 days of incubation. In addition to these levels, at 12 days, 200 or 250 \i.c. and at 16 days of incubation 200, 250, or 300 [/.c. I 131 were injected. At each incubation period, 12 eggs were injected with 0.2 ml. distilled water to serve as controls. A total of 276 eggs were used. Eighth day of incubation was selected as the initial injection period since it was reported that thyroid colloid droplets appeared at 9 to 10 days of incubation in the normal chick embryo (Fujita and Nagata, 1962) and that radioiodine was incorporated in the colloid-containing follicle on the 11th day of incubation (Hansborough and Khan, 1951). While the embryonic thyroid had the ability to concentrate iodine as early as the 7th and 9th day of incubation, all the iodine in the 7th day embryo was non-precipitable while most of the iodine in the 9th day embryo was organically bound (Wollman and Zwilling, 1953). Since levels as low as 5 jxc. I 131 were adequate to reduce I 131 uptake by the thyroids of cockerels receiving it as 16 day embryos (Seigel and Mraz, 1965) 0, 0.5, 1, 2, 3, 4, 5, 25, and 50 (xc. I 131 were injected into at least 18 eggs each at 16 days of incubation to ascertain how low a level of I 131 could measurably affect the thyroid.
TABLE 1.—Embryonic response to varying levels
98
F. R. MRAZ
TABLE 2.—Embryonic response to varying levels of I1, injected into the egg at the 16th day of in I 131 injected
Eggs injected Chicks hatched
JltC.
12 11 12 14 14 14 12 16 14
18 18 18 18 18 18 18 20 21
0.0 0.5 1.0 2.0 3.0 4.0 5.0 25.0 50.0
at the 50 JJIC. level.
The maximum amounts of I 131 found in the eggs from hens intramuscularly administered 0.5, 1.0, 2.0, and 4 mc. I 131 were 13, 35, 58, and 88 (J.C, respectively. These were found in the 5 or 6 day eggs. No effect could be seen on growth rate of chicks regardless of the amount of I 131 found in the egg at time of incubation. However, as I 131 found in the egg at time of incubation increased, (Figure 1) the thyroid weights of chicks at 4 weeks of age hatched from these eggs decreased. The uptake of I 131 in these chicks at 4 weeks of age also decreased. DISCUSSION Lower dosages than those reported by Winchester et al. (1949), Mellen and Wentworth (1962) and Seigel and Mraz (1965) in the chick, and Maloof et al. (1952) in the rat, produced lingering 10
r
16
3°
14
"0 "% -
TABLE 3.—Growth rate and thyroid uptake of Iin 4-week-old chickens receiving varying levels of as 16-day embryos I
e cted
^'^' , "embryo
Alive at * « * .
Body weight
10 4 9 8 10 10 10 13 8
gm. 244a 216ab 235a 260a 227a 237a 231a 205ab 175b
/xC.
0.0 0.5 1.0 2.0 3.0 4.0 5.0 25.0 50.0
I
by Im
o* Thyroid wt.(mg.) •> 1131 content (%)
O O
12
0
10
-
° o
131
uptake thyroid
%
6.2a 5.5a 5.0a 2.7b 2.2bc 1.9bcd 1.3cd 0.68de 0.06e
a, b, c, d, e Any two means having the same letter are not significantly different (P>0.05) while any two means not having the same letters are significantly different by multiple range test (Duncan, 1955).
8
$ 6
••• • •*
4
• 2
O
10
20
30
40
50
60
70
I131 in egg ( p C ) FIG. 1. Weight and I™ content of 4-week-old chicks hatched from eggs varying in I131 at start of incubation.
Downloaded from http://ps.oxfordjournals.org/ at Northern Arizona University on June 2, 2015
bryos. In addition eggs that received SO, 100, and 150 JJIC. I131 embryos were found to be alive on the 29th day of incubation. Hatchability in embryos injected with 50 |j.c. I 131 appeared to improve the later in the incubation period the activity was administered. It was apparent (Table 2) that none of the I 131 levels (0 to 50 JJIC.) administered at 16 days of incubation affected hatchability. Growth to 4 weeks of age, however was significantly (P < 0.05) reduced at the 50 i^c. level (Table 3). Thyroid I 131 uptake at 4 weeks of age was reduced by all levels of I 131 administration, although the reductions were not significant (P > 0.05) until the 2 JAC. level. Vir-
tually no I 131 was taken up by the thyroid
EMBRYONIC RESPONSE TO IODINE-131
SUMMARY White Leghorn embryos were injected at 8, 12, or 16 days of incubation with varying levels of I131. Another group received the I 131 by transference from the hen. Most embryos receiving 100 or more [AC of I 131 were unable to absorb their yolk sac. Body weights and thyroid I 131 uptake were reduced in those receiving 50 and 2[AC. I131, respectively. Thyroid I 131 uptake by those receiving 50 JJIC. I 131 was negligible. Data on I 131 transference from
hens to embryos were in agreement with the above findings if 16-days decay of I 131 was considered in equilibrating the 2 experiments. REFERENCES Duncan, D. B., 19S5. Multiple range and multiple F tests. Biometrics, 11: 1-42. Fujita, H., and S. Nagata, 1962. Histological studies on the functional development of the thyroid gland of the chick embryo. 1. Histochemical observations. Arch. Histol. Japanicum, 22: 187-191. Hansborough, A. L., and M. Khan, 1951. The initial function of the chick thyroid gland with the use of radioiodine F " . J. Exp. Zool. 116: 447-453. LaBella, F. S., 1964. Stimulation of thyroidal I131 release in the day-old chick by a single injection of thyroxine or propylthiouracil. Endocrinology, 74: 294-297. Maloof, F., B. M. Dobyns and A. L. Vickery, 1952. The effects of various doses of radioactive iodine on the function and structure of the thyroid of the rat. Endocrinology, 50: 612-638. Mellen, W. J., and B. C. Wentworth, 1962. Observations on radiothyroidectomized chickens. Poultry Sci. 4 1 : 134-141. Okonski, J., F. W. Lengemann and C. L. Comar, 1960. The utilization of egg iodine by the chicken embryo. J. Exp. Zool. 145: 263-269. Rogler, J. C , H. E. Parker, F. N. Andrews and C. W. Carrick, 1949. Various factors affecting the iodine-131 uptake by embryonic thyroids. Poultry Sci. 30: 405-410. Seigel, H. S., and F. R. Mraz, 1965. F " uptake in radiothyroidectomized chicks. Poultry Sci. 44: 785-788. Winchester, C. F., C. L. Comar and G. K. Davis, 1949. Thyroid destruction by I m and replacement therapy. Science, 110: 302-304. Winchester, C. F., and G. K. Davis, 1952. Influence of thyroxin on growth of chickens. Poultry Sci. 3 1 : 31-34. Wollman, S. H., and E. Zwilling, 1953. Radioiodine metabolism in the chick embryo. Endocrinology, 52: 526-535.
APRIL 12-16. 50TH ANNUAL MEETING, FEDERATION OF AMERICAN SOCIETIES FOR EXPERIMENTAL BIOLOGY, ATLANTIC CITY, N. J. MAY 5-6. NATIONAL SYMPOSIUM ON ANIMAL WASTE MANAGEMENT, KELLOGG CENTER FOR CONTINUING EDUCATION, MICHIGAN STATE UNIVERSITY, EAST LANSING, MICHIGAN
Downloaded from http://ps.oxfordjournals.org/ at Northern Arizona University on June 2, 2015
damage to the embryonic thyroid. Correcting the I 131 levels found in eggs from dosed hens at time of incubation for decay of 2 half-lives, bring them in agreement with the between 1 and 2 [AC. necessary at the 16th day of incubation to produce damage to the embryos. Okonski et al. (1960) reported that in 6-day embryos, thyroids concentrated I 131 by a factor of 500 times over that of muscle. It would appear that the embryonic requirements for thyroxine are small until the 18th to 20th days of incubation since most of the embryos grow to this stage and then stop development. It has been reported that a sharp increase in I 131 uptake occurs in 20-day embryos over younger embryos suggesting a marked increase in thyroid activity (Rogler et al., 1959). Dayold chicks were considered to be hypothyroid (LaBella, 1964). These would tend to support our observations. It would appear in our work that even in those chicks which produced enough thyroxine to hatch, the thyroid could be damaged sufficiently to reduce growth.
99
P. N.
DUA AND
seconds was plotted against the log of vitamin K level, mcg./kg. of the diet (Fig. 1). The ratio of activity of MSBC to MPB was found to be 1:1.9 with 95% confidence limits between 1:1.6 and 1:2.3. These ratios are higher than the calculated ratio of 1:1.37 of MSBC and MPB, based on their actual menadione content. These results are essentially similar to those reported by Griminger (1965).
A study was conducted with chicks to compare the relative vitamin K activity of a new water soluble menadione analogue, menadione dimethylpyrimidinol bisulfite (MPB, containing 45.5% menadione) with that of menadione sodium bisulfite complex (MSBC, containing 32.8% menadione). The ratio of activity of MSBC to MPB on an equal weight basis was found by a parallel line bioassay procedure to be 1:1.9. ACKNOWLEDGMENTS
The authors wish to express their thanks to Dr. Walter J. Drapala for statistical ad-
DAY
vice, and Mrs. Geneva assistance. This work part by a grant-in-aid cal Corporation, Valley
Ray for laboratory was supported in from HeterochemiStream, New York,
REFERENCES Davies, O. L., 1958. Statistical Methods in Research and Production. Hafner Publishing Company, New York. Dua, P. N., and E. J. Day, 1965. High levels of menadione dimethylpyrimidinol bisulfite in broiler rations. Poultry Sci. 44: 1140-1141. Frost, D. V., H. S. Perdue and H. C. Spruth, 1956. Vitamin K activity of menadione sodium bisulfite in chickens. J. Nutrition, 59: 181-196. Griminger, P., 1965. Relative vitamin K potency of two water-soluble menadione analogues. Poultry Sci. 44: 210-213. Nelson, T. S., and L. C. Norris, 1960. Studies on the vitamin K requirement of the chick. 1. Requirements of the chick for vitamin Ki, menadione and menadione sodium bisulfite. J. Nutrition, 72: 137-144. Perdue, H. S., H. C. Spruth and D. V. Frost, 1957. Comparison of vitamin K activities of vitamin Ki and Klotogen (Menadione sodium bisulfite complex). Poultry Sci. 36: 633-635. Steel, R. G. D., and J. H. Torrie, 1960. Principles and Procedures of Statistics. McGraw-Hill Book Company, Inc., New York.
Embryonic Response to Iodme-1311 FRANK
R.
MRAZ
Agricultural Research Laboratory of The University of Tennessee, Oak Ridge, Tennessee1 (Received for publication July 2, 1965)
ODINE-131 with a half life of 8.05 days; has at least 4 beta emissions varying; from 0.08 to 0.72 mev. Eighty percent off each emission is composed of a 0.61 mevi beta and a 0.37 mev gamma emission. Io--
I
1
This manuscript is published with the permission of the Director of the University of Tennessee Agricultural Experiment Station, Knoxville. 2 Operated by the Tennessee Agricultural Experiment Station for the U.S. Atomic Energy Commission under Contract No. AT-40-1-GEN242.
dine concentrates in the thyroid, where, if radioactive, it can irradiate this tssue. This specificity enables small amounts of I 131 to produce serious damage to the thyroid. As little as 6 mc. I1S1 per 100 gm. of body weight injected into chicks was shown to completely destroy their thyroids (Winchester et al, 1949; Winchester and Davis, 1952). Normal growth rates were restored by injection of 1 to 12 gamma of thyroxine per 100 gm. of body weight. Mellen and Wentworth (1962) pretreated
Downloaded from http://ps.oxfordjournals.org/ at Northern Arizona University on June 2, 2015
SUMMARY
E. J.
97
EMBRYONIC RESPONSE TO IODINE-131
their birds with a low-iodine diet and thiouracil to reduce the I 131 necessary for thyroid destruction to 1.5 mc. per 100 gm. A series of experiments was conducted to determine the effect of I131 injections on embryos, to ascertain the lowest level at which damage to the embryo would occur, and to estimate the levels administered to the hen that would result in sufficient I 131 in the egg to harm the embryo.
of I131 injected into eggs (12 eggs per treatment) Days of incubation 8th Hatched
embryos
12 th Hatched
16th
embryos
12 12 12 7 0 0 0 0
5 12 12 12 12
Hatched
11 12 10 12 0 1 0 0 0
embryos
1 12 11 12 12 12
* Number of live embryos remaining in eggs that did not hatch.
The chicks that hatched were fed a commercial chick diet and water ad libitum. At 4 weeks of age the chicks were weighed and then intramuscularly injected with 25 (AC. carrier-free I 131 and sacrificed 48 hours later. Thyroids were removed and their I 131 contents determined. To assess the levels necessary in a single dose to the hen to damage the thyroids of chicks hatched from her eggs, 6 to 8 hens were intramuscularly injected with 0.5, 1, 2 or 4 mc. carrier-free I131. The I 131 contents of a total of 375 of their eggs were determined immediately prior to incubation by placing them over a well-type scintillation detector that had its upper shielding removed. The nutritional regime of the resulting chicks was similar to the present experiment. Intramuscular injection of I 131 occurred at 4 weeks of age and the chicks were sacrificed 24 hours later. Thyroids were removed, weighed and their content determined. RESULTS
Hatchability (Table 1) was reduced in embryos injected with I 131 levels of 25, 50, and 100 [i.c. or higher at 8, 12, and 16 days of incubation, respectively. All the remaining eggs were broken open at 22 days of incubation and were found to have live embryos with unabsorbed yolk sacs similar to those found in 18- or 19-day em-
Downloaded from http://ps.oxfordjournals.org/ at Northern Arizona University on June 2, 2015
EXPERIMENTAL Initially, 12 eggs were injected with 5, 25, 50, 100, or 150 [xc. of carrier-free I 131 as sodium iodide in basic sodium sulfite solution at 8, 12, or 16 days of incubation. In addition to these levels, at 12 days, 200 or 250 \i.c. and at 16 days of incubation 200, 250, or 300 [/.c. I 131 were injected. At each incubation period, 12 eggs were injected with 0.2 ml. distilled water to serve as controls. A total of 276 eggs were used. Eighth day of incubation was selected as the initial injection period since it was reported that thyroid colloid droplets appeared at 9 to 10 days of incubation in the normal chick embryo (Fujita and Nagata, 1962) and that radioiodine was incorporated in the colloid-containing follicle on the 11th day of incubation (Hansborough and Khan, 1951). While the embryonic thyroid had the ability to concentrate iodine as early as the 7th and 9th day of incubation, all the iodine in the 7th day embryo was non-precipitable while most of the iodine in the 9th day embryo was organically bound (Wollman and Zwilling, 1953). Since levels as low as 5 jxc. I 131 were adequate to reduce I 131 uptake by the thyroids of cockerels receiving it as 16 day embryos (Seigel and Mraz, 1965) 0, 0.5, 1, 2, 3, 4, 5, 25, and 50 (xc. I 131 were injected into at least 18 eggs each at 16 days of incubation to ascertain how low a level of I 131 could measurably affect the thyroid.
TABLE 1.—Embryonic response to varying levels
98
F. R. MRAZ
TABLE 2.—Embryonic response to varying levels of I1, injected into the egg at the 16th day of in I 131 injected
Eggs injected Chicks hatched
JltC.
12 11 12 14 14 14 12 16 14
18 18 18 18 18 18 18 20 21
0.0 0.5 1.0 2.0 3.0 4.0 5.0 25.0 50.0
at the 50 JJIC. level.
The maximum amounts of I 131 found in the eggs from hens intramuscularly administered 0.5, 1.0, 2.0, and 4 mc. I 131 were 13, 35, 58, and 88 (J.C, respectively. These were found in the 5 or 6 day eggs. No effect could be seen on growth rate of chicks regardless of the amount of I 131 found in the egg at time of incubation. However, as I 131 found in the egg at time of incubation increased, (Figure 1) the thyroid weights of chicks at 4 weeks of age hatched from these eggs decreased. The uptake of I 131 in these chicks at 4 weeks of age also decreased. DISCUSSION Lower dosages than those reported by Winchester et al. (1949), Mellen and Wentworth (1962) and Seigel and Mraz (1965) in the chick, and Maloof et al. (1952) in the rat, produced lingering 10
r
16
3°
14
"0 "% -
TABLE 3.—Growth rate and thyroid uptake of Iin 4-week-old chickens receiving varying levels of as 16-day embryos I
e cted
^'^' , "embryo
Alive at * « * .
Body weight
10 4 9 8 10 10 10 13 8
gm. 244a 216ab 235a 260a 227a 237a 231a 205ab 175b
/xC.
0.0 0.5 1.0 2.0 3.0 4.0 5.0 25.0 50.0
I
by Im
o* Thyroid wt.(mg.) •> 1131 content (%)
O O
12
0
10
-
° o
131
uptake thyroid
%
6.2a 5.5a 5.0a 2.7b 2.2bc 1.9bcd 1.3cd 0.68de 0.06e
a, b, c, d, e Any two means having the same letter are not significantly different (P>0.05) while any two means not having the same letters are significantly different by multiple range test (Duncan, 1955).
8
$ 6
••• • •*
4
• 2
O
10
20
30
40
50
60
70
I131 in egg ( p C ) FIG. 1. Weight and I™ content of 4-week-old chicks hatched from eggs varying in I131 at start of incubation.
Downloaded from http://ps.oxfordjournals.org/ at Northern Arizona University on June 2, 2015
bryos. In addition eggs that received SO, 100, and 150 JJIC. I131 embryos were found to be alive on the 29th day of incubation. Hatchability in embryos injected with 50 |j.c. I 131 appeared to improve the later in the incubation period the activity was administered. It was apparent (Table 2) that none of the I 131 levels (0 to 50 JJIC.) administered at 16 days of incubation affected hatchability. Growth to 4 weeks of age, however was significantly (P < 0.05) reduced at the 50 i^c. level (Table 3). Thyroid I 131 uptake at 4 weeks of age was reduced by all levels of I 131 administration, although the reductions were not significant (P > 0.05) until the 2 JAC. level. Vir-
tually no I 131 was taken up by the thyroid
EMBRYONIC RESPONSE TO IODINE-131
SUMMARY White Leghorn embryos were injected at 8, 12, or 16 days of incubation with varying levels of I131. Another group received the I 131 by transference from the hen. Most embryos receiving 100 or more [AC of I 131 were unable to absorb their yolk sac. Body weights and thyroid I 131 uptake were reduced in those receiving 50 and 2[AC. I131, respectively. Thyroid I 131 uptake by those receiving 50 JJIC. I 131 was negligible. Data on I 131 transference from
hens to embryos were in agreement with the above findings if 16-days decay of I 131 was considered in equilibrating the 2 experiments. REFERENCES Duncan, D. B., 19S5. Multiple range and multiple F tests. Biometrics, 11: 1-42. Fujita, H., and S. Nagata, 1962. Histological studies on the functional development of the thyroid gland of the chick embryo. 1. Histochemical observations. Arch. Histol. Japanicum, 22: 187-191. Hansborough, A. L., and M. Khan, 1951. The initial function of the chick thyroid gland with the use of radioiodine F " . J. Exp. Zool. 116: 447-453. LaBella, F. S., 1964. Stimulation of thyroidal I131 release in the day-old chick by a single injection of thyroxine or propylthiouracil. Endocrinology, 74: 294-297. Maloof, F., B. M. Dobyns and A. L. Vickery, 1952. The effects of various doses of radioactive iodine on the function and structure of the thyroid of the rat. Endocrinology, 50: 612-638. Mellen, W. J., and B. C. Wentworth, 1962. Observations on radiothyroidectomized chickens. Poultry Sci. 4 1 : 134-141. Okonski, J., F. W. Lengemann and C. L. Comar, 1960. The utilization of egg iodine by the chicken embryo. J. Exp. Zool. 145: 263-269. Rogler, J. C , H. E. Parker, F. N. Andrews and C. W. Carrick, 1949. Various factors affecting the iodine-131 uptake by embryonic thyroids. Poultry Sci. 30: 405-410. Seigel, H. S., and F. R. Mraz, 1965. F " uptake in radiothyroidectomized chicks. Poultry Sci. 44: 785-788. Winchester, C. F., C. L. Comar and G. K. Davis, 1949. Thyroid destruction by I m and replacement therapy. Science, 110: 302-304. Winchester, C. F., and G. K. Davis, 1952. Influence of thyroxin on growth of chickens. Poultry Sci. 3 1 : 31-34. Wollman, S. H., and E. Zwilling, 1953. Radioiodine metabolism in the chick embryo. Endocrinology, 52: 526-535.
APRIL 12-16. 50TH ANNUAL MEETING, FEDERATION OF AMERICAN SOCIETIES FOR EXPERIMENTAL BIOLOGY, ATLANTIC CITY, N. J. MAY 5-6. NATIONAL SYMPOSIUM ON ANIMAL WASTE MANAGEMENT, KELLOGG CENTER FOR CONTINUING EDUCATION, MICHIGAN STATE UNIVERSITY, EAST LANSING, MICHIGAN
Downloaded from http://ps.oxfordjournals.org/ at Northern Arizona University on June 2, 2015
damage to the embryonic thyroid. Correcting the I 131 levels found in eggs from dosed hens at time of incubation for decay of 2 half-lives, bring them in agreement with the between 1 and 2 [AC. necessary at the 16th day of incubation to produce damage to the embryos. Okonski et al. (1960) reported that in 6-day embryos, thyroids concentrated I 131 by a factor of 500 times over that of muscle. It would appear that the embryonic requirements for thyroxine are small until the 18th to 20th days of incubation since most of the embryos grow to this stage and then stop development. It has been reported that a sharp increase in I 131 uptake occurs in 20-day embryos over younger embryos suggesting a marked increase in thyroid activity (Rogler et al., 1959). Dayold chicks were considered to be hypothyroid (LaBella, 1964). These would tend to support our observations. It would appear in our work that even in those chicks which produced enough thyroxine to hatch, the thyroid could be damaged sufficiently to reduce growth.
99