Studies were carried out to clarify the effects of 17β-estradiol on tibia histo-morphometry in chick embryos. Varying levels of 17β-estradiol (0, 20, 40, or 80μg) were injected every other day from the 10th to 18th day of incubation into the air chamber of eggs. On the 20th day of incubation, right tibiae were excised and diaphyseal cross sections were examined by light microscopy. Morphological differences were quantified using a computerlized histomorphometric technique. The administration of two higher doses of 17β-estradiol caused significant increase in histomorphometric indices of bone formation. Total bone area, measured at middiaphysis, greatly increased in the 17β-estradiol-treated embryos compared to controls receiving the vehicle alone. This increase was associated with marked increase in bone volume, expressed as percentage of the bone matrix area. The number and areas of periosteal osteoblasts were remarkably enhanced in the 17β-estradiol-treated group. 17β-Estradiol treatment did not affect the two histomorphometric indices of bone resorption, nuclei number and area of osteoclast. Exogenous 17β-estradiol would thus appear to induce periosteal osteoblast differentiation and stimulate bone formation in the chick embryo tibia.

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Interleukin 2 (IL 2) activities estimated by lymphocyte activation were determined in the supernatants of phytohemagglutinin (PHA)-stimulated chicken peripheral blood lymphocyte (PBL) and splenocyte cultures. Dialysable T cell suppressive factor in culture supernatant of chicken PBL was also investigated. The peak activities of IL 2 in the supernatants of PHA-stimulated chicken lymphocyte cultures were observed during earlier period of incubation than those of mammalian species studied so far. The result suggests that chicken lymhocytes produce and secrete IL 2 more rapidly than mammalian lymphocytes, or chicken IL 2 is more labile to inactivate. Presence of dialysable (low molecular weight) factor that suppressed IL 2-promoted T cell activation in chicken PBL culture supernatant was suggested from the results that dialysis of PHA-stimulated PBL culture medium amplified the activation of Concanavalin A (ConA)-pretreated (IL 2 receptor positive) PBL, and that the dialysate of PHA-stimulated PBL culture medium conversely suppressed the activation of ConA-pretreated PBL. Accordingly, T cell activating factor (IL 2) and suppressive factor thought to be mixed in the mitogenstimulated chicken PBL culture supernatant. Secretion of the suppressive factor into culture medium may be a reason for lowering of IL 2 activity in the medium.

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In order to clarify the causes for growth inhibition in thyroid hormone-deficient chickens, we investigated the effects of thyroid hormones on the growth of muscle, bone, viscera and fat.
Male chickens (White Leghorn, Hisex) were used and the following four experimental groups were set up; (1) sham operation, (2) T₄(L-thyroxine) injection, (3) autotransplantation, and (4) thyroidectomy. Thyroidectomy and sham operation were performed at the age of 10-11 days and the ectomized thyroid glands were immediately autotransplanted into the subcutaneous tissue of the breast. For the autotransplanted binds except the autotransplantation group, the glands were removed again at the 27-28 days of age and a half of them were injected with 1.0-1.5±g/100g•bwt of T₄ intraperitoneally from 31 to 70 days old. For all 4 groups, feed consumption was examined every day and body weight was measured once a week from 45 to 70 days old. Total weight of muscles, bones, viscera and fats per bird was determined at the age of 71-74 days. Body weight gain, feed consumption, and the weights of muscle, bone, viscera and fat were not significantly different among the 3 groups; sham operation, T₄ injection and autotransplantation. The thyroidectomy group showed significant decrease in all items except fat weight. The decrease rates of muscle and bone weight relative to the autotransplantation group were 32.6% and 30.3%, respectively, but the actual difference was about 135g in muscle and about 36g in bone. On the other hand, fat weight of the thyroidectomized chicks showed the largest value among the 4 groups and the increase rate relative to the autotransplantation group exceeded 200%. However, the increase in actual weight was only about 39g.
Therefore, it may be concluded that the growth inhibition in the thyroid hormone -deficient chicken depends on the retardation in growth of muscle, bone and viscera, especially muscle retardation is the most important factor responsible for growth inhibition.

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A technique for fistulating at the different intestinal parts of Pekin ducks for successive collection of digesta was established. The digestibilities and feed passage times of a formula diet, corn, barley, milo and rice were determined in ducks fistulated at the middle portion of ileum, distal end of ileum and distal end of rectum using our new fistulation method.
The digestibilities of crude protein, crude fat and nitrogen-free extract at the distal end of rectum showed only a slight increse compared with these at the middle portion of ileum in all the feeds used, except that the digestibility of crude protein of rice showed remarkable increase and the digestibility of crude fat of barley decreased at the distal end of rectum. However, the digestibility of crude fiber apparently increased from the middle portion to the distal end of ileum. The digestibilities of crude protein, crude fat and nitrogen-free extract related to that of the distal end of rectum were 97-99% on an average of all the feeds used, whereas that of crude fiber at the middle portion of ileum was only 30%. The feed passage times were about 110, 140 and 160 minutes at the each fistulated portions, respectively, in all the feeds used except for the rice which took longer times.
The results of the present study indicate that the digestion of crude protein, crude fat and nitrogen-free extract are almost completed up to the middle portion of ileum, and that the portion between the middle of the ileum and the intestine caudal may play a main role in the digestion of crude fiber.

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To evaluate a degree of genetic differentiation among commercial quail populations and to compare it with that of laboratory quail populations, 25 enzymes and proteins encoded by 34 presumed loci were examined by starch or agar gel electrophoresis. Six Japanese and one French commercial quail populations were analysed in the present survey. From the preceding reports, data of one Canadian commercial and four Canadian laboratory quail populations (KIMURA et al., 1990: CHENG et al., 1992), one Japanese commercial quail population (KIMURA et al., 1990) and three wild quail populations (KIMURA & FUJII, 1989) were quoted and included for the calculation.
Mean and standard deviation of the proportion of polymorphic loci (Ppoly) and of the average heterozygosity per individual (H) estimated for the nine commercial populations were 0.302±0.055 and 0.101±0.010, respectively. These values are approx-imately 1.25 times higher than those estimated for the four Canadian laboratory quail populations.
The fixation index (FST) value of 0.055 was calculated for the commercial and 0.155 for the laboratory quail populations. The result suggests no significant differentiation among the commercial quail populations.
According to the genetic distance and the results of principal component analyses, the quail populations examined in the present survey could be classified into following four clusters: (1) three wild quail populations, (2) seven Japanese commercial and one Canadian laboratory quail populations, (3) two Canadian laboratory quail populations and (4) three quail populations selected for heavy body weight.

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Since an increasing proportion of eggs is being marketed, a demand may arise for a specific strain of hen which lays eggs with the composition suited to the various type of industry and family users. Hence, there is a need for information on the genetic parameters of egg compositional traits for effective selection. Considerable phenotypic and genetic variation of these traits has existed and it has been suggested that internal egg quality can be genetically improved through selection.
The purpose of this study was to examine the characteristics of the egg-type commercial strains (CS) regarding various egg qualities and to compare with the results of similar work in 1975.
Eggs sampled from thirteen CS at about seven to ten months of age were used for determining twenty-four egg traits. These CS were conveniently divided into white egg shell type and brown egg shell type groups. According to order of average egg weight in each group were coded WA to WH and BI to BM, respectively.The results obtained were as follows:
1. Differences between estimated means of thirteen CS were significant (P<0.05) in the analysis of variance of the 24 egg traits determined in this study.
2. The means of egg weight among CS were estimated 59.8g to 65.9g in white egg type group and 62.3g to 70.2g in brown egg type group. These values were not related with age of hen in each SC.
3. The order of average albumen weight in each group were paralleled with egg weight. The means of yolk weight in middle egg weight CS were larger than the other strains in white egg type group.
4. On egg component weight percentages, the high yolk percentage was estimated in smaller egg weight CS of brown egg type, and in middle egg weight CS of white egg type. The WG strain had the lowest mean of yolk percentage, and relatively high mean of albumen percentage in spite of small egg size strain.
5. It was estimated that the albumen height and Haugh units of the high albumen percentage strain were higher means than the other strains. There were not observed apparent differences between white and brown egg type strains for the means of the shell thickness and the shell strength.
6. It was noted that similar correlation coefficients were determined on these CS.Simple correlation matrixes of these CS were analysed by varimax rotation of principal composites. The structure vectors in the composite variables obtained were classified into five or six closely associated groups. Commercial strain differences of associated groups were slightly demonstrated by this analysis.
7. When the results of this study were compared with the measurements in 1975, the means of egg weight and albumen weight were generally increased in the compared strains. It was demonstrated that the yolk weight of WE strain was remarkably decreased and the Haugh unit of WE strain and the egg shape index of WF strain were clearly increased.

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Specific bindings to radioiodinated chicken vasoactive intestinal peptide (VIP) were measured in the membrane fraction of the cephalic and the caudal lobes of anterior pituitary of Japanese native breed of chicken, Gifujidori. The specific binding per mg protein in the cephalic lobe was much greater in incubating hens than in laying hens and less in roosters than in the hens. In the caudal lobe, however, it was not different between the incubating and laying hens and between the hens and the roosters. The greater binding in the cephalic lobe in the incubating hens may be concerned in the incubation behavior through the stimulatory action of VIP for prolactin secretion.

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