Uropygial Gland Research Articles

Chemical regulation of body feather microbiota in a wild bird.

The microbiota has a broad range of impacts on host physiology and behaviour, pointing out the need to improve our comprehension of the drivers of host-microbiota composition. Of particular interest is whether the microbiota is acquired passively, or whether and to what extent hosts themselves shape the acquisition and maintenance of their microbiota. In birds, the uropygial gland produces oily secretions used to coat feathers that have been suggested to act as an antimicrobial defence mechanism regulating body feather microbiota. However, our comprehension of this process is still limited. In this study, we for the first time coupled high-throughput sequencing of the microbiota of both body feathers and the direct environment (i.e., the nest) in great tits with chemical analyses of the composition of uropygial gland secretions to examine whether host chemicals have either specific effects on some bacteria or nonspecific broad-spectrum effects on the body feather microbiota. Using a network approach investigating the patterns of co-occurrence or co-exclusions between chemicals and bacteria within the body feather microbiota, we found no evidence for specific promicrobial or antimicrobial effects of uropygial gland chemicals. However, we found that one group of chemicals was negatively correlated to bacterial richness on body feathers, and a higher production of these chemicals was associated with a poorer body feather bacterial richness compared to the nest microbiota. Our study provides evidence that chemicals produced by the host might function as a nonspecific broad-spectrum antimicrobial defence mechanism limiting colonization and/or maintenance of bacteria on body feathers, providing new insight about the drivers of the host's microbiota composition in wild organisms.

Individual- and Species-Specific Skin Microbiomes in Three Different Estrildid Finch Species Revealed by 16S Amplicon Sequencing.

An animals' body is densely populated with bacteria. Although a large number of investigations on physiological microbial colonisation have emerged in recent years, our understanding of the composition, ecology and function of the microbiota remains incomplete. Here, we investigated whether songbirds have an individual-specific skin microbiome that is similar across different body regions. We collected skin microbe samples from three different bird species (Taeniopygia gutatta, Lonchura striata domestica and Stagonopleura gutatta) at two body locations (neck region, preen gland area). To characterise the skin microbes and compare the bacterial composition, we used high-throughput 16S rRNA amplicon sequencing. This method proved suitable for identifying the skin microbiome of birds, even though the bacterial load on the skin appeared to be relatively low. We found that across all species, the two evaluated skin areas of each individual harboured very similar microbial communities, indicative of an individual-specific skin microbiome. Despite experiencing the same environmental conditions and consuming the same diet, significant differences in the skin microbe composition were identified among the three species. The bird species differed both quantitatively and qualitatively regarding the observed bacterial taxa. Although each species harboured its own unique set of skin microbes, we identified a core skin microbiome among the studied species. As microbes are known to influence the host's body odour, our findings of an individual-specific skin microbiome might suggest that the skin microbiome in birds is involved in the odour production and could encode information on the host's genotype.

Feather mite abundance varies but symbiotic nature of mite‐host relationship does not differ between two ecologically dissimilar warblers

Feather mites are obligatory ectosymbionts of birds that primarily feed on the oily secretions from the uropygial gland. Feather mite abundance varies within and among host species and has various effects on host condition and fitness, but there is little consensus on factors that drive variation of this symbiotic system. We tested hypotheses regarding how within‐species and among‐species traits explain variation in both (1) mite abundance and (2) relationships between mite abundance and host body condition and components of host fitness (reproductive performance and apparent annual survival). We focused on two closely related (Parulidae), but ecologically distinct, species: Setophaga cerulea (Cerulean Warbler), a canopy dwelling open‐cup nester, and Protonotaria citrea (Prothonotary Warbler), an understory dwelling, cavity nester. We predicted that feather mites would be more abundant on and have a more parasitic relationship with P. citrea, and within P. citrea, females and older individuals would harbor greater mite abundances. We captured, took body measurements, quantified feather mite abundance on individuals’ primaries and rectrices, and monitored individuals and their nests to estimate fitness. Feather mite abundance differed by species, but in the opposite direction of our prediction. There was no relationship between mite abundance and any measure of body condition or fitness for either species or sex (also contrary to our predictions). Our results suggest that species biology and ecological context may influence mite abundance on hosts. However, this pattern does not extend to differential effects of mites on measures of host body condition or fitness.

Acquisition of Uropygial Gland Microbiome by Hoopoe Nestlings

Mutualistic symbioses between animals and bacteria depend on acquisition of appropriate symbionts while avoiding exploitation by non-beneficial microbes. The mode of acquisition of symbionts would determine, not only the probability of encountering but also evolutionary outcomes of mutualistic counterparts. The microbiome inhabiting the uropygial gland of the European hoopoe (Upupa epops) includes a variety of bacterial strains, some of them providing antimicrobial benefits. Here, the mode of acquisition and stability of this microbiome is analyzed by means of Automated rRNA Intergenic Spacer Analysis and two different experiments. The first experiment impeded mothers' access to their glands, thus avoiding direct transmission of microorganisms from female to offspring secretions. The second experiment explored the stability of the microbiomes by inoculating glands with secretions from alien nests. The first experiment provoked a reduction in similarity of microbiomes of mother and nestlings. Interestingly, some bacterial strains were more often detected when females had not access to their glands, suggesting antagonistic effects among bacteria from different sources. The second experiment caused an increase in richness of the microbiome of receivers in terms of prevalence of Operational Taxonomic Units (OTUs) that reduced differences in microbiomes of donors and receivers. That occurred because OTUs that were present in donors but not in receivers incorporated to the microbiome of the latter, which provoked that cross-inoculated nestlings got similar final microbiomes that included the most prevalent OTUs. The results are therefore consistent with a central role of vertical transmission in bacterial acquisition by nestling hoopoes and support the idea that the typical composition of the hoopoe gland microbiome is reached by the incorporation of some bacteria during the nestling period. This scenario suggests the existence of a coevolved core microbiome composed by a mix of specialized vertically transmitted strains and facultative symbionts able to coexist with them. The implications of this mixed mode of transmission for the evolution of the mutualism are discussed.

Comparative Histomorphochemical Studies on Uropygial Gland of Kadaknath and White Leghorn Breeds of Poultry

The present study was conducted on ten each uropygial glands of 6 to 8 months old healthy Kadaknath and White Leghorn breeds of poultry. The tissue samples were stained by H and E for normal histological structures, Verhoeff’s stain for collagen and elastic fibers, PAS (Periodic Acid Schiff’s) for glycogen and Alcian Blue PAS method for acid mucopolysaccharides. The uropygial gland in Kadaknath and White Leghorn was composed of two lobes. Each lobe had a single duct and these ducts were joined together by isthmus. The thickness of capsule was more in White Leghorn than Kadaknath breed. The lumen of tubules showed higher concentration of secretary product in Kadaknath breed. Numbers of tubules were higher in Kadaknath. No aggregation of lymphocytes was found in the preen gland of White Leghorn, whereas in Kadaknath, there was large number of lymphocytes aggregation alongwith lymphatic nodules. Melanin pigmentation was the characteristic feature of Kadaknath which was found towards the central cavity and in between ductules. The capsule of White Leghorn showed intense PAS activity, while moderate activity was found in Kadaknath breed of poultry. Intense ACPase reaction was noticed in capsule of uropygial gland of Kadaknath and White Leghorn breeds of poultry.

Kocuria uropygioeca sp. nov. and Kocuria uropygialis sp. nov., isolated from the preen glands of Great Spotted Woodpeckers (Dendrocopos major)

Two new species of Gram-positive cocci were isolated from the uropygial glands of wild woodpeckers (Dendrocopos major) originating from different locations in Germany. A polyphasic approach confirmed the affiliation of the isolates to the genus Kocuria. Phylogenetic analysis based on the 16S rRNA gene showed high degree of similarity to Kocuria koreensis DSM 23367T (99.0% for both isolates). However, low ANIb values of <80% unequivocally separated the new species from K. koreensis. This finding was further corroborated by DNA fingerprinting and analysis of polar lipid profiles. Furthermore, growth characteristics, biochemical tests, MALDI-TOF MS analysis, and G+C contents clearly differentiated the isolates from their known relatives. Besides, the woodpecker isolates significantly differed from each other in their whole-cell protein profiles, DNA fingerprints, and ANIb values. In conclusion, the isolated microorganisms constitute members of two new species, for which the names Kocuria uropygioeca sp. nov. and Kocuria uropygialis sp. nov. are proposed. The type strains are 36T (DSM 101740T=LMG 29265T) and 257T (=DSM 101741T=LMG 29266T) for K. uropygialis sp. nov. and K. uropygioeca sp. nov., respectively.

Morphological and genetic factors shape the microbiome of a seabird species (Oceanodroma leucorhoa) more than environmental and social factors

BackgroundThe microbiome provides multiple benefits to animal hosts that can profoundly impact health and behavior. Microbiomes are well-characterized in humans and other animals in controlled settings, yet assessments of wild bird microbial communities remain vastly understudied. This is particularly true for pelagic seabirds with unique life histories that differ from terrestrial bird species. This study was designed to examine how morphological, genetic, environmental, and social factors affect the microbiome of a burrow-nesting seabird species, Leach’s storm petrel (Oceanodroma leucorhoa). These seabirds are highly olfactory and may rely on microbiome-mediated odor cues during mate selection. Composition and structure of bacterial communities associated with the uropygial gland and brood patch were assessed using 16S rRNA amplicon-based Illumina Mi-Seq analysis and compared to burrow-associated bacterial communities. This is the first study to examine microbial diversity associated with multiple body sites on a seabird species.ResultsResults indicate that sex and skin site contribute most to bacterial community variation in Leach’s storm petrels and that major histocompatibility complex (MHC) genotype may impact the composition of bacterial assemblages in males. In contrast to terrestrial birds and other animals, environmental and social interactions do not significantly influence storm petrel-associated bacterial assemblages. Thus, individual morphological and genetic influences outweighed environmental and social factors on microbiome composition.ConclusionsContrary to observations of terrestrial birds, microbiomes of Leach’s storm petrels vary most by the sex of the bird and by the body site sampled, rather than environmental surroundings or social behavior.

Songbird chemical signals reflect uropygial gland androgen sensitivity and predict aggression: implications for the role of the periphery in chemosignaling.

Chemical signals can provide useful information to potential mates and rivals. The production mechanisms of these signals are poorly understood in birds, despite emerging evidence that volatile compounds from preen oil may serve as chemosignals. Steroid hormones, including testosterone (T), may influence the production of these signals, yet variation in circulating T only partly accounts for this variation. We hypothesized that odor is a T-mediated signal of an individual's phenotype, regulated in part by androgen sensitivity in the uropygial gland. We quantified natural variation in chemosignals, T, uropygial gland androgen sensitivity, and aggressive behavior in dark-eyed juncos (Junco hyemalis). The interaction between circulating T and androgen receptor transcript abundance significantly correlated with volatile concentrations in male, but not female, preen oil. In both sexes, odorant variables correlated with aggressive response to an intruder. Our results suggest that preen oil volatiles could function as signals of aggressive intent, and, at least in males, may be regulated by local androgen receptor signaling in the uropygial gland. Because these behavioral and chemical traits have been linked with reproductive success, local regulation of androgen sensitivity in the periphery has the potential to be a target of selection in the evolution of avian olfactory signaling.

Preservation of uropygial gland lipids in a 48-million-year-old bird.

Although various kinds of organic molecules are known to occur in fossils and rocks, most soft tissue preservation in animals is attributed to melanin or porphyrins. Lipids are particularly stable over time-as diagenetically altered 'geolipids' or as major molecular constituents of kerogen or fossil 'geopolymers'-and may be expected to be preserved in certain vertebrate tissues. Here we analysed lipid residues from the uropygial gland of an early Eocene bird using pyrolysis gas chromatography mass spectroscopy. We found a pattern of aliphatic molecules in the fossil gland that was distinct from the host oil shale sediment matrix and from feathers of the same fossil. The fossil gland contained abundant n-alkenes, n-alkanes and alkylbenzenes with chain lengths greater than 20, as well as functionalized long-chain aldehydes, ketones, alkylnitriles and alkylthiophenes that were not detected in host sediment or fossil feathers. By comparison with modern bird uropygial gland wax esters, we show that these molecular fossils are likely derived from endogenous wax ester fatty alcohols and fatty acids that survived initial decay and underwent early diagenetic geopolymerization. These data demonstrate the high fidelity preservation of the uropygial gland waxes and showcase the resilience of lipids over geologic time and their potential role in the exceptional preservation of lipid-rich tissues of macrofossils.

Sex-specific differences in preen gland size of Zebra Finches during the course of breeding

ABSTRACT In birds, the preen gland produces a waxy secretion that protects the plumage from environmental conditions and ectoparasites and is, therefore, important for feather maintenance, individual quality, and health. Several studies have demonstrated that the size of the preen gland and the composition of its secretion change throughout the course of reproduction, thus indicating an increased requirement for preen gland secretion during the breeding season. However, the exact timing of the gland's size increase is unknown. To get information about this temporal pattern, we repeatedly measured the preen glands in 22 breeding pairs of adult domesticated Zebra Finches (Taeniopygia guttata) during the course of reproduction (prior to the breeding season, on the day the first egg was laid, on the day the first chick hatched, on the day the first chick fledged, and after the chicks became independent). Zebra Finches have biparental care, in which both sexes are involved in incubation and food provisioning. ...

Uropygial gland volume and malaria infection are related to survival in migratory house martins

Pathogens such as bacteria, fungi and malaria and related haemosporidians provoke negative effects on the fitness of their hosts. Animals have developed a range of defensive mechanisms to resist or eliminate these parasitic infections and their negative fitness costs. The uropygial gland secretion has been proposed to act as defensive barrier of skin and plumage in the fight against bacteria and fungi, and may prevent birds from acquiring haemosporidian infections. Thus, the secretion of uropygial glands of birds may favour survival of individuals. However, whether uropygial gland secretion influence survival remains unknown. Here we explore if the size of the uropygial gland and malaria infection influence survival of house martins Delichon urbica. We showed, for the first time, that the volume of the uropygial gland positively predicted survival prospects of malaria infected house martins. Malaria infected birds had the lowest probability of survival, with the effect of gland size on survival prospects depending on infection: infected house martins with larger uropygial glands were better able to survive to the next breeding season, while infected birds with small uropygial glands were not. These results highlight the importance of uropygial gland secretion in the life history of wild birds.

Seasonal changes in the preen wax composition of the Herring gull Larus argentatus

The preen gland produces oily secretion, which smeared onto a bird’s plumage improves its maintenance. The main components of the secretion are waxes, and its composition often changes during the year. The aim of this study was to determine the differences in the chemical composition of preen waxes in adult herring gulls Larus argentatus, captured in Poland in winter and in the breeding season. Preen gland secretions of herring gulls consist of monoester waxes, composed of about 29 saturated C7–C16 fatty acids and about 51 saturated C11–C20 alcohols. Unbranched-octanoic acid and n-hexadecanol dominated fatty acid and alcohol fractions, respectively, but 2-methyl-branched compounds were numerous in all individuals. The chemical compositions of fatty acids and alcohols differ between winter and the breeding season. In breeding gulls, 2-monomethyl-branched fatty acids were lower in content or could not be found, contrary to herring gulls in winter, where 2-monomethyl-substituted fatty acids were the second most abundant among all the fatty acids. Breeding gulls had also a higher content of n-octanoic acid and n-hexadecanol and a lower content of 2,6- and 2,8-dimethyl-substituted fatty acids than individuals caught during the winter. Differences in fatty acid composition were greater in breeding males, which incubate more often at night than breeding females. Hence, chemical changes in the preen wax composition in males may have evolved as additional nocturnal protection against mammalian predators which use olfaction to detect their prey and which are more active at night; however, this needs to be tested. Olfactory-based mate recognition in the colony also cannot be excluded at this stage of experimentation.

Histological and Morphological Study of the Uropygial Gland in Gull (Larus canus)

Histological and Morphological Study of the Uropygial Gland in Gull (Larus canus)

The effect of uropygial gland secretions of Spectacled Thrushes (Turdus nudigenis) on feather degradation and bacterial growth in vitro

We studied if uropygial secretions protect Neotropical Spectacled (=Bare-eyed) Thrushes (Turdus nudigenis) from feather-degrading bacteria naturally harbored in their plumage and explored the possible mechanisms involved in feather protection. We chose Spectacled Thrushes because we had previously isolated from their plumage several bacterial strains with keratinolytic properties. We showed that preen secretions, in the amounts preened naturally onto the feathers of Spectacled Thrushes, retarded in vitro the degradation of feathers by Bacillus cereus, a bacterium previously shown to degrade feathers severely. However, we found no evidence that in liquid culture, uropygial secretions had a bacteriostatic effect of a chemical nature. On the contrary, preen secretions stimulated the growth of four keratinolytic bacteria naturally hosted by Spectacled Thrushes. Uropygial secretions of Spectacled Thrushes were sterile, thus we also discarded the hypothesis that feather protection could have been due to antimicrobials produced by symbiotic bacteria harbored in the uropygial gland. Our results support that uropygial secretion of Spectacled Thrushes retarded feather degradation not through a chemical effect, but possibly by alternative mechanisms such as the formation of a physical barrier that isolated feather-degrading bacteria from feathers.

Embryogenesis of the Uropygial Glands in the Laysan Albatross (Phoebastria immutabilis (Rothschild, 1893): Procellariiformes)

An avian uropygial gland is located on the mid-dorsum of the tail, and is the only external gland found in birds. Most studies have focused on the function, gross anatomy and chemical nature of this gland, with little research on its ontogeny. The purpose of this study was to examine the development of this gland in a series of Laysan Albatross (Phoebastria immutabilis) embryos. Specimens were examined anatomically and histologically. It was found that grooves preceded glandular development by many stages. The embryogenesis of the uropygial gland was divided into 6 phases: preinception, groove inception, mesodermal separation, migrating mesodermal cells, oval shaped "depressions", constriction and finally glandular inception. No other gland is known to develop similarly, though there may be parallels with femoral gland development. In comparison to other bird species, the length of the development period in the Albatross, as well as other compounding factors, make it difficult to determine the significance of these observations. The development of a mesodermal band, soon to be a connective tissue capsule, is more complex than originally described in ducks. Thus, the unique nature of this gland is established, but the significance of the observations required further studies into uropygial gland development. Anat Rec, 300:1420-1428, 2017. © 2017 Wiley Periodicals, Inc.

Presence of persistent organic pollutants in a breeding common tern (Sterna hirundo) population in Ireland.

Persistent organic pollutants (POPs) are chemical compounds of environmental concern due to their toxic, persistent nature and their ability to bio-accumulate in biological tissue. Seabirds, for often being at the top of the food web, have been used as monitors of environmental pollutants. Adverse effects caused by POPs have been reported in common terns (Sterna hirundo) since the 1970s. Egg shell thinning, embryo and hatchling deformities have been reported for this species. Environmental legislation, such as the Oslo-Paris Convention (OSPAR), has agreed on the monitoring of concentration of POPs in common terns. This study set out to investigate contemporary concentrations of polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs), organochlorine pesticides (OCPs) and brominated flame retardants (BFRs) in common terns breeding in Ireland, along with congener profiles. Investigation was conducted in live (n=15) and dead birds (n=20) to test for the efficiency of different methodologies using preen oil and feathers versus liver and preen gland. Mean concentrations of POPs followed the order: PCB (36.48ng/g ww feather) > PAH (30.01ng/g ww feather) > OCP (13.36ng/g ww feather) > BFR (1.98ng/g ww feather) in live birds; and PAH (46.65ng/g ww preen gland) > PCB (44.11ng/g ww preen gland) > OCP (15.15ng/g ww liver) > BFR (5.07ng/g ww liver) in dead birds. Comparison of contaminant results with toxicity pre-established levels concluded that this population of common terns in Ireland is not at risk of anomalies caused by POPs. However, some levels are higher in comparison to the ones established by OSPAR's EcoQO and must be monitored periodically.

Histomorphological study of uropygial gland of pekin duck (Anas platyrhnchos domesticus)

The study included 20 birds of Pekin duck (Anas platyrhnchos domesticus) for study the histological of uropygial gland (10 males + 10 females), the weights were between (1411-1582 gm) for males and (1350-1980 gm) female. Routine Histological Techniques was done and stained by Hematoxylin and Eosin (H&amp;E), Periodic Acidic Schiff (PAS), Masson's trichrome stains. Histological sections of the uropygial gland of Pekin ducks showed that the gland consist of the capsule, parenchyma, isthmus and uropygial papillae. The capsule consist of Dense irregular connective tissue. The mean thickness of capsule around the gland lobes were (56.321?17.206µm) and around the uropygial papillae were (67.208?14.996 µm). The capsule tissues continuous in between the secretory tubules to form trabecular.The parenchyma consists from secretory tubules arranged around the central cavity of gland, the cells that lining the secretory tubules consist of four types the basal cells, intermediate cells, secretory cells and degenerative cells. The study included 20 birds of Pekin duck (Anas platyrhnchos domesticus) for study the histological of uropygial gland (10 males + 10 females), the weights were between (1411-1582 gm) for males and (1350-1980 gm) female. Routine Histological Techniques was done and stained by Hematoxylin and Eosin (H&amp;E), Periodic Acidic Schiff (PAS), Masson's trichrome stains. Histological sections of the uropygial gland of Pekin ducks showed that the gland consist of the capsule, parenchyma, isthmus and uropygial papillae. The capsule consist of Dense irregular connective tissue. The mean thickness of capsule around the gland lobes were (56.321?17.206µm) and around the uropygial papillae were (67.208?14.996 µm). The capsule tissues continuous in between the secretory tubules to form trabecular.The parenchyma consists from secretory tubules arranged around the central cavity of gland, the cells that lining the secretory tubules consist of four types the basal cells, intermediate cells, secretory cells and degenerative cells.

The Bacterial Community Found on the surface Purple Martin (Progne subis) Eggs

Introduction: The community of microorganisms that lines the surface of avian eggs is the first line of defense against infection by pathogenic bacteria. The protective role of this community is derived from its composition and several studies have focused on identifying the bacterial components. While a diverse group of avian species has been studied, multiple species within the same family have not been independently studied. This depth is necessary to determine the degree of flexibility or plasticity within the community. Method: The goal of this study was to identify the bacterial microorganisms found lining the eggshells of an avian species classified within the Hirundinidae family, the Purple Martin (Progne subis). Culture-dependent techniques revealed a predominance of Pseudomonas before and after clutch completion. Result: Interestingly our results correlate with studies involving Pied Flycatchers, House Wrens, and Eurasian Magpies rather than Tree and Violet-Green Swallows. Conclusion: Given the variances between Pied Flycatchers, House Wrens, Eurasian Magpies and Purple Martins in regard to breeding habitat, diet, nest construction, and incubation behaviors, we hypothesize that a strong selective force may be provided by uropygial gland secretions or preen oil.

Preen oil and bird fitness: a critical review of the evidence.

The uropygial gland is a holocrine complex exclusive to birds that produces an oleaginous secretion (preen oil) whose function is still debated. Herein, I examine critically the evidence for the many hypotheses of potential functions of this gland. The main conclusion is that our understanding of this gland is still in its infancy. Even for functions that are considered valid by most researchers, real evidence is scarce. Although it seems clear that preen oil contributes to plumage maintenance, we do not know whether this is due to a role in reducing mechanical abrasion or in reducing feather degradation by keratinophilic organisms. Evidence for a function against pathogenic bacteria is mixed, as preen oil has been demonstrated to act against bacteria in vitro, but not in vivo. Nor is it clear whether preen oil can combat pathogenic bacteria on eggshells to improve hatching success. Studies on the effect of preen oil against dermatophytes are very scarce and there is no evidence of a function against chewing lice. It seems clear, however, that preen oil improves waterproofing, but it is unclear whether this acts by creating a hydrophobic layer or simply by improving plumage structure. Several hypotheses proposed for the function of preen oil have been poorly studied, such as reduction of drag in flight. Similarly, we do not know whether preen oil functions as repellent against predators or parasites, makes birds unpalatable, or functions to camouflage birds with ambient odours. On the other hand, a growing body of work shows the important implications of volatiles in preen oil with regard to social communication in birds. Moreover, preen oil clearly alters plumage colouration. Finally, studies examining the impact of preen oil on fitness are lacking, and the costs or limitations of preen-oil production also remain poorly known. The uropygial gland appears to have several non-mutually exclusive functions in birds, and thus is likely to be subject to several selective pressures. Therefore, future studies should consider how the inevitable trade-offs among different functions drive the evolution of uropygial gland secretions.

Histomorphological study of uropygial gland of pekin duck (Anas platyrhnchos domesticus)

The study included 20 birds of Pekin duck (Anas platyrhnchos domesticus) for study the histological of uropygial gland (10 males + 10 females), the weights were between (1411-1582 gm) for males and (1350-1980 gm) female. Routine Histological Techniques was done and stained by Hematoxylin and Eosin (H&amp;E), Periodic Acidic Schiff (PAS), Masson's trichrome stains. Histological sections of the uropygial gland of Pekin ducks showed that the gland consist of the capsule, parenchyma, isthmus and uropygial papillae. The capsule consist of Dense irregular connective tissue. The mean thickness of capsule around the gland lobes were (56.321?17.206µm) and around the uropygial papillae were (67.208?14.996 µm). The capsule tissues continuous in between the secretory tubules to form trabecular.The parenchyma consists from secretory tubules arranged around the central cavity of gland, the cells that lining the secretory tubules consist of four types the basal cells, intermediate cells, secretory cells and degenerative cells. The study included 20 birds of Pekin duck (Anas platyrhnchos domesticus) for study the histological of uropygial gland (10 males + 10 females), the weights were between (1411-1582 gm) for males and (1350-1980 gm) female. Routine Histological Techniques was done and stained by Hematoxylin and Eosin (H&amp;E), Periodic Acidic Schiff (PAS), Masson's trichrome stains. Histological sections of the uropygial gland of Pekin ducks showed that the gland consist of the capsule, parenchyma, isthmus and uropygial papillae. The capsule consist of Dense irregular connective tissue. The mean thickness of capsule around the gland lobes were (56.321?17.206µm) and around the uropygial papillae were (67.208?14.996 µm). The capsule tissues continuous in between the secretory tubules to form trabecular.The parenchyma consists from secretory tubules arranged around the central cavity of gland, the cells that lining the secretory tubules consist of four types the basal cells, intermediate cells, secretory cells and degenerative cells.