FREE ELECTRONIC LIBRARY - Abstracts, online materials

«ABSTR•CT.Histological criteria indicate that thyroid glands are organized into follicles at about the same time of incubation in JapaneseQuail ...»




ABSTR•CT.--Histological criteria indicate that thyroid glands are organized into follicles at

about the same time of incubation in JapaneseQuail (precocial)and Ringed Turtle Dove (altricial) embryos,but dove thyroidsdevelopmore slowly, are much smaller and are much lessactive than quail thyroids by the time of hatching. These resultsindicate thyroid readinessfor participation in early endothermic responses precocial hatchlings, and relative thyroid inactivity in young ecof tothermic altricial nestlings.--Departmentof Biology, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061. Accepted 12 April 1976.

THYROID hormonesare known to be important determinants of metabolic rate and heat production in adult birds. In addition, the time course of developing thyroid function closelyparallels developingthermoregulatoryability in precocialyoung that hatch at a relatively advanced stageof development(seeFreeman 1971, for the data on domesticchickens;McNabb et al. 1972 and Spiers et al. 1974 for the data on Japanese Quail [Coturnix coturnix japonica]). These precocial hatchlings exhibit some thermoregulatoryability shortly after hatching although they do not become truly homeothermic severalweeks;the actual time course homeothermic for of development dependson the species.In contrast, altricial birds hatch at a lessdeveloped stageand are dependenton parental care and feedingfor sometime. Altricial hatchlings are ectothermicfor the first few daysafter hatching, but acquire thermoregulatory ability duringthe nestlingperiod, and are homeothermic the time of fledging by (usually at about 2-3 weeks of age, Dawson and Hudson 1970). Using the single criterion of epithelial cell height, Dawson and Allen (1960) concludedthat thyroid function in nestlingVesper Sparrows(Pooecetes gramineus)matchesor exceeds that of adultsand, therefore,anticipatesthe developmentof homeothermy.Rol'nik (1968) stated that the thyroid of altricial birds differentiates into follicles and becomes physiologicallyactive relatively later than in precocial birds, but this comparisonis based on birds that differ markedly in body size and length of their incubation periods.

The objective of this paper is to comparethyroid gland developmentduring the embryonicperiod in a precocialspecies (Japanese Quail), and in an altricial species (Ringed Turtle Doves, Streptopeliarisoria). Although these speciesboth have an incubation period of about 16+ days duration, quail exhibit endothermicresponses to cold shortly after hatching (Spiers et al. 1974) while doves are presumably ectothermic for at least the first few days after hatching (Breitenbachand Baskett 1967 have shown that nestlingMourning Doves are ectothermicfor at least the first 3 days). Our choice of these specieswas determined by the equal length of their incubation periodsplus patterns of developmenttypical of thoseconsidered precocial and altricial.

–  –  –

of incubation.In dove embryos,similar degrees colloidvacuolizationwere seenin of bothred and bluestainedcolloid; vacuolization waslackingin chromophobic colloid.

In quail thyroidsFD increased significantlyfrom 14.5/• on day 10 to 23.3/• on day 16 (Fig. 3). This change in FD in quail was due to an increase in CD with no significant change in ECH (mean ECH through days 10-16 was 4.5/• with the greatestcell height of 5.7/• 2 days prior to hatching; [Fig. 3]). In embryonicdove thyroids FD did not increasesignificantly(19.6/• on day 16), and ECH decreased significantlyfrom 6.5/• on day 11 to 4.9/• on day 16 (Fig. 3). Follicle diameter was significantlygreater in quail thyroidsthan in dove thyroidson day 16; ECH did not differ significantlybetween the two species (Fig. 3).

–  –  –

thyroid size is considerablysmaller and organization of the gland into follicles is slowerthan in quail embryos(Figs. 1 and 2). Stainingreactionsindicatethat only of the thyroidfolliclesare activein the doveat the time of hatching.In dovethyroids the existence somechromophobic of colloidlate in the incubationperiodparallelsthe conditionin chickenembryos(Romanoff 1960)and is in contrastto the conditionin embryonic quail thyroids.

Colloid vacuolizationdid not appear to be a particularly useful indicator of hormone mobilizationin theseavian embryos.Vacuolizationwas presentin both active and inactivechromophilic colloid,but the degree vacuolization of was not correlated with either changes cell height, or times when hormonereleaseis indicatedby in changesin thyroidal iodine content (McNabb et al. 1972).

Measurementsof follicle dimensionsindicate that quail thyroid growth, after organizationinto completefollicles,occurs increases both follicle number (Fig. 2) by in and FD (Fig. 3). As ECH doesnot increase, but CD does,cell numbersor cell width in the follicle walls must increase.In dove thyroids, FD doesnot changesignificantly during this period. The lack of significantdifferencesbetween species ECH, in although other criteria indicate differencesin thyroid activity, suggests this measurementis poor as a singlecriterionfor comparingthyroid activity betweendifferent avian species, but the generalpattern of ECH changes may be one useful sourceof information. In this study, ECH in quail thyroids showed the same pattern of changes that McNabb et al. (1972) were able to correlatewith the pattern of stable iodine content of the glands. In embryonicdoves, ECH measurements similar to are thoseof hatchling and adult Vesper Sparrows,but lessthan ECH measurements in 2-8-day nestling sparrows (Dawson and Allen 1960).

The histologicalcriteria for thyroid activity usedin this study show good correlation betweenthe time course changes thyroid gland activity, and the patternsof of in developingthermoregulatoryability in theseprecocialand altricial species. Japanese Quail are precocial, and from the time of hatching usemetabolic energyto gain some independence environmental temperature. These quail chickshave active thyroid of glands during most of the latter half of the incubation period. High thyroid hormone secretionoccursjust prior to the initiation at hatching of endothermicresponses to cold (McNabb et al. 1972, Spiers et al. 1974). The patterns of both thyroid gland development and thermoregulatory ability in Japanese Quail are similar to those described chickens,the precocialspecies for that has receivedthe most study (see review by Freeman 1971). The time course of developing thermoregulation in JapaneseQuail is prolonged, relative to that in chickens, as might be expected because of the high rates of heat loss resulting from the quail's small body size.

JapaneseQuail attain thermoregulatoryability more rapidly than do the larger Bobwhite Quail (Borchelt and Ringer 1973), a pattern that is reversedfrom that expected on the basisof body size. Thus while Japanese Quail seeman appropriatechoicefor studyingthe role of the thyroid gland in the thermoregulationof precocialbirds, their rate of post-hatchingdevelopmentis unusually rapid in comparisonto that of other quail.

The altricial pattern of developmentis characterizedby ectothermyin the early hatchling period with high growth efficiency, at least partly becauselittle energy is expendedfor thermoregulation.The thyroid glands of altricial Ringed Turtle Doves showed little evidence of activity by the time of hatching. These resultsare consistent with the low metabolic rates in altricial nestlingsthat remain ectothermicfor at least severaldaysafter hatching (seeBreitenbachand Baskett 1967 for work on Mourning 74-2 McNABBANDMCNABB [Auk, Vol. 94 Doves). The small proportionof active thyroid folliclesduring the embryonicperiod in doves indicates at least some production of thyroid hormones. As thyroid hormonesappear to be necessary normal growth and developmentof avian embryos for (seereview by Betz 1971), the low level of thyroid hormonesmay be sufficientfor this purposebut insufficientto elevatethe metabolicrate to the high levelsrequired for homeothermy. One line of evidence(ECH values in Vesper Sparrow thyroids, Dawson and Allen 1960) indicatesthat the thyroids of altricial nestlingsshow histological evidenceof activity prior to the time when these nestlingsexhibit endothermicresponsesto cold.

Evidence of thyroid hormone production prior to the initiation of endothermic responses cold in both quail and doves indicates thyroid participation in these to metabolic events, but does not reveal the mechanisminvolved in their onset. A marked increasein the release of thyroid hormones could be either the trigger for initiating thermoregulatoryresponses merelypart of the metabolicconditionpreor requisiteto central nervousinitiation of thermoregulatoryresponses.

Distinguishing betweenthesetwo possibilities require neurophysiological will experimentsand measurements circulatingthyroid hormonelevels during the period of developing of thermoregulatory ability.

Similar works:

«Tracking microdeletions of the AZF region in a patrilineal line of infertile men R.G. Rodovalho, J.T. Arruda and K.K.V.O. Moura Departamento de Biologia, Núcleo de Pesquisas Replicon, Universidade Católica de Goiás, Goiânia, GO, Brasil Corresponding author: K.K.V.O. Moura E-mail: kkverolli@ucg.br; katiakarinav@yahoo.com.br Genet. Mol. Res. 7 (3): 614-622 (2008) Received May 6, 2008 Accepted June 18, 2008 Published July 8, 2008 ABSTRACT. Male infertility is considered to be a...»

«© 2016. Published by The Company of Biologists Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution and reproduction in any medium provided that the original work is properly attributed. Pax8 controls thyroid follicular polarity through Cadherin-16 Petrina Koumarianou1, Gonzalo Goméz-López2 and Pilar Santisteban1 Instituto de Investigaciones...»

«ISSN: 0975-8585 Research Journal of Pharmaceutical, Biological and Chemical Sciences A Survey Based On Cloth Pattern Recognition for Optically Defective Humanity. Annammal S*, and Sakthi prabha R. Department of ECE, Sathyabama University, Chennai, Tamil Nadu, India. ABSTRACT The recognition of Clothes pattern is a challenging task for optically impaired people.Due to the large intra class pattern variation this becomes a challenging task in computer vision. The clothing pattern is categorised...»

«1 Patrolling the mind’s boundaries Abstract: Defenders of the extended mind thesis say that it is possible that some of our mental states may be constituted, in part, by states of the extrabodily environment. Often they also add that such extended mentation is a commonplace phenomenon. I argue that extended mentation, while not impossible, is either nonexistent or far from widespread. Genuine beliefs as they occur in normal biologically embodied systems are informationally integrated with...»

«InVEST Scenarios Case Study: Eastern Arc Mountains, Tanzania Brendan Fisher, Ruth Swetnam, Neil Burgess, Emily McKenzie, Simon Willcock excerpted from Developing Scenarios to Assess Ecosystem Service Tradeoffs This case study highlights a real-world example of using InVEST scenarios to inform decisions about land use. In this example, scenarios were developed, ecosystem service impacts were assessed, and the results were used to make sound policy decisions. The case study offers background on...»

«Pak. J. Bot., 36(4): 711-717, 2004. ANALYSIS OF AIRBORNE POLLEN FALL IN USAK, TURKEY ADEM BICAKCI, R. DUNDAR KOC*, SEVCAN TATLIDIL, O. NURI BENLIOGLU* Department of Biology, Science Faculty, Uludag University, Gorukle, Bursa, Turkey. Abstract In this study, pollen grains were identified by using Durham sampler in the atmosphere of Usak, Turkey. During the year 2000, a total number of 5,464 grains per cm2 were recorded. Pollen fall comprised of grains belonging 39 taxa consisting of 25 arboreal,...»

«Integr Psych Behav DOI 10.1007/s12124-011-9176-5 R E G U L A R A RT I C L E “Minding the Gap”: Imagination, Creativity and Human Cognition Etienne Pelaprat & Michael Cole # Springer Science+Business Media, LLC 2011 Abstract Inquiry into the nature of mental images is a major topic in psychology where research is focused on the psychological faculties of imagination and creativity. In this paper, we draw on the work of L.S. V ygotsky to develop a cultural-historical approach to the study of...»

«Obenchain, F. D., and J. H. Oliver, Jr. 1976. The heart and arterial circulatory system of ticks (Atari : (Ixodioidea). J. Arachnol. 3 :57-74. THE HEART AND ARTERIAL CIRCULATORY SYSTEM OF TICKS (ACARI : IXODOIDEA) ' Frederick D. Obenchai n James H. Oliver, Jr. Institute of Arthropodology and Parasitology Department of Biology, Georgia Southern Colleg e Statesboro, Georgia 3045 8 ABSTRAC T The heart and arterial (efferent) circulatory system in Argas radiatus and Ornithodoros...»

«Old Dominion University ODU Digital Commons Biological Sciences Theses & Dissertations Biological Sciences Fall 2015 The Effects of Urbanization on Tick Parasitism Rates in Birds of Southeastern Virginia Erin Leigh Heller Old Dominion University Follow this and additional works at: http://digitalcommons.odu.edu/biology_etds Part of the Ecology and Evolutionary Biology Commons, and the Ornithology Commons Recommended Citation Heller, Erin Leigh, The Effects of Urbanization on Tick Parasitism...»

«the long shadow of temperament & jerome kagan nancy snidman the belknap press of harvard university press Cambridge, Massachusetts London, England 2004 contents Prologue 1 1. Overview 4 2. The Tapestries of Temperament 34 3. Biological Responses to Unfamiliarity 64 4. Behavioral and Biological Assessments 106 5. Integrating Behavior and Biology 190 6. Implications 217 References 246 Index 283 1 overview Over the past 25 years, we have been intrigued by two distinct categories of children who...»

«Micronesica 2013-01: 1–26 Known and potential ticks and tick-borne pathogens of Micronesia1 NANCY VANDER VELDE AND BRIAN VANDER VELDE Biological Consultants, Marshall Islands; P. O. Box 1603, Majuro, MH 96960 nancyv@ntamar.net Abstract—Ticks have long been known to be the vectors of diseases, to both humans and animals. Yet very little work has been done regarding tick species found in Micronesia, and much of that is now decades old. Many parts of Micronesia have long undergone considerable...»

«Lepr Rev (2008) 79, 242– 253 REVIEW The biology of nerve injury in leprosy DAVID M. SCOLLARD Chief, Research Pathology, National Hansen’s Disease Programs, LSU-SVM, Skip Bertman Dr. Baton Rouge, LA 70803, USA Accepted for publication 9 September 2008 Introduction Nerve injury is a central feature of the pathogenesis of leprosy, and the basic biological aspects have been reviewed in many textbooks.1 – 3 Selected aspects of current research on this subject have also been the subject of...»

<<  HOME   |    CONTACTS
2017 www.abstract.dislib.info - Abstracts, online materials

Materials of this site are available for review, all rights belong to their respective owners.
If you do not agree with the fact that your material is placed on this site, please, email us, we will within 1-2 business days delete him.