Influence of an early grafted adenohypophysis on the thyroid of the chick embryo

Maraud, R; Audine, M; Stoll, R

doi:10.1016/0016-6480(83)90047-3

Cited by 5 publications

(4 citation statements)

References 24 publications

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“…At Day 8.5, the thyroid can secrete thyroxine into the circulation of the embryo (Daugeras and Lachiver, 1972;Daugeras et ah, 1976). Maraud et al (1975Maraud et al ( , 1983 stated that there are two distinct peaks of thyroid activity during the development of the chick embryo corresponding to the aforementioned developmental aspects. The thyroid concentrates iodine and synthesizes colloid up to about Day 7 and can produce hormones at Day 8.5.…”

Section: Resultsmentioning

confidence: 99%

“…The injection at Day 0 was intended to correspond to the first peak in thyroid activity (Maraud et al, 1983), and the second injection was intended to correspond to the second peak in thyroid activity (Christensen and Biellier, 1982). In general, it can be stated that injections of thyroid hormones at the first peak in thyroid activity had no effect (Tables 1, 4, and 5) or a depressing effect (Tables 2 and 3) on hatchability.…”

Section: Resultsmentioning

confidence: 99%

“…The injection needle penetrated the egg a distance of 150 to 160 mm and the injection hole was sealed with paraffin. Because there are two distinct thyroid development stages during incubation (Maraud et al, 1983), hormone injections were made in all experiments at two times corresponding to the biphasic thyroid development. Groups of 748 eggs each were injected with hormones or amino acid on Days 0 and 25 of incubation, respectively.…”

Section: Methodsmentioning

confidence: 99%

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Supplemental Thyroid Hormones and Hatchability of Turkey Eggs

Christensen

1985

Poultry Science

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Fertile turkey eggs were injected with thyroid hormones to test the effects of exogenous hormones on hatchability. Physiological doses of thyroxine (T4) and triiodothyronine (T3) of 50 and 25 ng, respectively, injected at setting, depressed hatchability. Conversely, injections of T4 and T3 at 25 days of incubation significantly (P less than .05) improved hatchability. Injections with thyroid-stimulating hormone (TSH) or tyrosine had no significant effect on hatchability when injected at setting or at 25 days of incubation. Injections of thyroid-releasing hormone (TRH) had no effect on hatchability when injected at setting but significantly (P less than .05) improved hatchability when injected at 25 days of incubation. Because T4 and T3 significantly (P less than .05) depressed hatchability when injected whereas TSH and TRH had no effect on hatchability when injected at setting, these data suggest classic negative feedback mechanisms function very early in the embryonic turkey. The improvement in hatchability observed when thyroid hormones were injected at 25 days of incubation offers further evidence that hypothyroidism may be a cause of poor hatchability among turkey eggs.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

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Supplemental Thyroid Hormones and Hatchability of Turkey Eggs

Christensen

1985

Poultry Science

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“…In order to evaluate the functional capabilities of the pituitary in relation to thyroid activity, Maraud et al (1983) implanted the adenohypophysis from an 11-day-old chicken embryo into the extra-embryonic coelom of a 3-day-old recipient. The adenohypophysis strongly influenced the development of the thyroid gland in the 3-dayold embryo by an increased volume of the gland and an increased percentage of colloid and radio-iodide from day 10 of incubation.…”

Section: Functionality Of the Avian Hypothalamic-pituitary-thyroid Axismentioning

confidence: 99%

Involvement of the hypothalamic-pituitary-thyroid axis and its interaction with the hypothalamic-pituitary-adrenal axis in the ontogeny of avian thermoregulation: a review

Debonne

Baarendse

Brand

et al. 2008

World's Poultry Science Journal

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The emergence of thermoregulation in avian species is a complex matter in which neural as well as hormonal processes are involved. In a previous paper, the neural aspects of primary avian thermoregulation were discussed. In this paper the role of the hypothalamus-pituitary-thyroid axis (HPT-axis) and the hypothalamus-pituitaryadrenal axis (HPA-axis) in the ontogeny of avian thermoregulation is evaluated. The regulatory mechanisms and different important hormones of both axes, which have stimulatory or inhibitory effects, are discussed. Because the onset of functionality of the thermoregulatory system is of great interest, the ontogeny and functionality of the hormonal axes are clarified. There is a great difference between precocial and altricial birds in hormonal events as well as in neural processes which are involved in the emergence of thermoregulation. In precocial avian species the HPT-axis becomes functional during the mid-to late embryonic period while the same axis only becomes fully functional during the first week post-hatch in altricial avian species.As early as the sixties, the emergence of homeothermy in chickens was investigated. It was concluded that the thyroid gland plays an important role in the thermoregulatory mechanisms of newly hatched chicks. More recent studies however were not able to show any direct effect of the thyroid hormones on the thermoregulation of day-old chicks, although blocking the conversion of T4 to T3 caused a decrease in body temperature in young chicks. Thyrotropin releasing hormone (TRH) is known to act in thermoregulation in mammals and several authors have found an effect of TRH on the metabolism of young and older chicks. However, the exact mechanism still remains unclear.Because the HPT-and the HPA-axis show close relationships, the role of the HPAaxis in the ontogeny of thermoregulation is also taken into consideration in this review. In mammals as well as in birds, corticotropin releasing hormone (CRH) is involved in the primary thermoregulation.We conclude that the HPT-axis has an important role in the ontogeny of avian thermoregulation. The exact role of the HPA-axis remains largely unclear although at least CRH is definitely of some importance.

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Hormones and Growth in Domestic Animals

Scanes

1999

Comprehensive Physiology

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Influence of an early grafted adenohypophysis on the thyroid of the chick embryo

Cited by 5 publications

References 24 publications

Supplemental Thyroid Hormones and Hatchability of Turkey Eggs

Supplemental Thyroid Hormones and Hatchability of Turkey Eggs

Involvement of the hypothalamic-pituitary-thyroid axis and its interaction with the hypothalamic-pituitary-adrenal axis in the ontogeny of avian thermoregulation: a review

Hormones and Growth in Domestic Animals

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