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Lin S, Liu R, Shen J, Huang X, Chen C, Lin S, Jia R. The typical developmental trajectory and energy requirements of Shitou goose during the embryonic stage. Poult Sci 2024; 103:104039. [PMID: 39111150 PMCID: PMC11362789 DOI: 10.1016/j.psj.2024.104039] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2024] [Revised: 06/01/2024] [Accepted: 06/24/2024] [Indexed: 08/26/2024] Open
Abstract
Low hatchability has been a persistent challenge in the goose industry. Establishing standard atlases and comprehending embryonic development patterns are essential to improving the hatching rates of goose eggs. However, comprehensive descriptions of normal atlases, embryonic development, and energy requirements in geese are lacking. In this study, a total of 120 fertile eggs from well-known large Shitou goose were incubated using 12 nesting purebred female geese. During hatching, both the temperature of the eggshells and the weight of eggs were recorded, and daily photographs of the embryos were captured to monitor their development closely. After hatching, counted the number of pores per unit area of eggshells by choosing eggs from without sperm, dead embryos, and normally hatched. Furthermore, 150 Shitou goose eggs were hatched by automatic incubator, with adjustments made based on observed normal developmental stages that incubated by female geese. The eggs were carefully opened to meticulously document embryonic morphology and create a detailed development map. Measurements were taken of the eye diameter, length of the lower beak, tarsometatarsus bone, and embryo length. Subsequently, an analysis was conducted to assess the calcium, phosphorus, crude protein, and crude fat content to study the energy requirements for embryo development. characteristics on the 7th, 15th, 23rd and 28th days of Shitou goose hatching corresponded to the 5th, 10th, 17th and 19th days of chicken egg incubation, respectively. These days were distinguished individually by "visible embryo's eye", "closure", "sealing the door", and "flashing hair". Besides, the hatch rate of the incubator reached 86.67%, and the cumulative water loss rate increased with embryo age. Notably, normally developing embryos displayed a significantly higher number of pores on the eggshell surface compared to dead embryos (P < 0.05). Additionally, embryonic body length, eyeball diameter, and lower beak length exhibited continuous growth until day 19 of incubation, while tarsometatarsus length increased steadily from days 12 to 31. Liver size measurement began on the 10th day of incubation, while both leg and chest muscles showed continuous growth from the 12th day. For energy demand, the embryo primarily relied on protein sourced from the egg yolk within the first 10 days of development. Afterward, the egg yolk provided both protein and fat for embryonic growth. In summary, this study has generated a comprehensive developmental map for Shitou goose embryos, offering valuable insights into their growth and morphological changes throughout the incubation period. This map can serve as a reference for optimizing machine incubation techniques to enhance goose egg hatching rates and provide fresh perspectives on the development of geese.
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Affiliation(s)
- Shudai Lin
- College of Coastal Agricultural Sciences, Guangdong Ocean University, 524088 Zhanjiang, Guangdong, PR China
| | - Ruizi Liu
- College of Coastal Agricultural Sciences, Guangdong Ocean University, 524088 Zhanjiang, Guangdong, PR China
| | - Jixiang Shen
- College of Coastal Agricultural Sciences, Guangdong Ocean University, 524088 Zhanjiang, Guangdong, PR China
| | - Xiaodong Huang
- College of Coastal Agricultural Sciences, Guangdong Ocean University, 524088 Zhanjiang, Guangdong, PR China
| | - Canjie Chen
- Shantou Chenghai Chaopeng Ecological Breeding Co., Ltd., 515825 Shantou, Guangdong, PR China
| | - Shanhong Lin
- Guangdong Lixing Agriculture Development Co., Ltd., 515700 Chaozhou, Guangdong, PR China
| | - Rumin Jia
- College of Coastal Agricultural Sciences, Guangdong Ocean University, 524088 Zhanjiang, Guangdong, PR China.
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Biesek J. The physicochemical features of eggshell, thick albumen, amniotic fluid, and yolk during chicken embryogenesis. Poult Sci 2023; 102:103119. [PMID: 37832191 PMCID: PMC10585332 DOI: 10.1016/j.psj.2023.103119] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2023] [Revised: 09/09/2023] [Accepted: 09/12/2023] [Indexed: 10/15/2023] Open
Abstract
The study aimed to analyze the hatching egg and physiochemical features of eggshells, thick albumen, amniotic fluid, and yolk during the incubation of Ross 308 chicken eggs. Eggs (n = 755) were incubated for 21 d. Quality analysis of fresh eggs was performed. Eggshells, albumen, and yolk were collected from fresh eggs and incubation d 1, 7, and 14. Eggshell thickness and strength, pH, vitelline membrane strength, fatty acid (FA) in the yolk, pH, viscosity, lysozyme activity, and crude protein content in thick albumen and amniotic fluid were analyzed. Hatching parameters were calculated. Egg weight loss was constant (8.04% overall). Lower egg surface temperature was found on d 7 compared to d 4, 14, and 18. A lower thickness of posthatch eggshells was found. The strength of the vitelline membrane significantly decreased within 24 h (by over 58%). During incubation, there was a decrease in thick albumen/amniotic fluid pH; an opposite trend was found in yolk pH. The vitelline membrane strength was negatively correlated with the albumen pH. Lysozyme activity was higher in fresh thick albumen and up to 2 wk of incubation. On d 7, the lowest activity was found in the amniotic fluid. On d 14, lysozyme activity increased in amniotic fluid. The higher viscosity of the thick albumen was demonstrated on d 7 and 14 of incubation. The lowest viscosity in amniotic fluid was found on the same days. Crude protein content was higher in thick albumen (d 7 and 14) and lowest in amniotic fluid on d 7. The FA content changed between d 0 and 14. The results indicate different use of FA, where PUFA decreased. Eggshell is used in the last week of incubation. The thick albumen is reduced, while the biological value of amniotic fluid is increasing. Lysozyme activity, viscosity, and crude protein content may be interdependent. It may indicate the flow of substances and the transfer of functions from the thick albumen to the amniotic fluid during chicken embryogenesis.
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Affiliation(s)
- Jakub Biesek
- Department of Animal Breeding and Nutrition, Faculty of Animal Breeding and Biology, Bydgoszcz University of Science and Technology, 85-084 Bydgoszcz, Poland.
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3
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Jia M, Reynolds KL, Wong EA. Effects of high incubation temperature on tight junction proteins in the yolk sac and small intestine of embryonic broilers. Poult Sci 2023; 102:102875. [PMID: 37406432 PMCID: PMC10339051 DOI: 10.1016/j.psj.2023.102875] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2023] [Revised: 06/01/2023] [Accepted: 06/13/2023] [Indexed: 07/07/2023] Open
Abstract
During the transition from incubation to hatch, the chicks shift from obtaining nutrients from the yolk sac to the intestine. The yolk sac tissue (YST) and small intestine serve as biological barriers between the yolk or gut contents and the blood circulation. These barriers must maintain structural integrity for optimal nutrient uptake as well as protection from pathogens. The objective of this study was to investigate the effect of high incubation temperature on mRNA abundance of the tight junction (TJ) proteins zona occludens 1 (ZO1), occludin (OCLN), claudin 1 (CLDN1), and junctional adhesion molecules A and 2 (JAMA, JAM2) and the heat shock proteins (HSP70 and HSP90) in the YST and small intestine of embryonic broilers. Broiler eggs were incubated at 37.5°C. On embryonic day 12 (E12), half of the eggs were switched to 39.5°C. YST samples were collected from E7 to day of hatch (DOH), while small intestinal samples were collected from E17 to DOH. The temporal expression of TJ protein mRNA from E7 to DOH at 37.5°C and the effect of incubation temperature from E13 to DOH were analyzed by one-way and two-way ANOVA, respectively and Tukey's test. Significance was set at P < 0.05. The temporal expression pattern of ZO1, OCLN, and CLDN1 mRNA showed a pattern of decreased expression from E7 to E13 followed by an increase to DOH. High incubation temperature caused an upregulation of ZO1 and JAM2 mRNA in the YST and small intestine. Using in situ hybridization, OCLN and JAMA mRNA were detected in the epithelial cells of the YST. In addition, JAMA mRNA was detected in epithelial cells of the small intestine, whereas JAM2 mRNA was detected in the vascular system of the villi and lamina propria. In conclusion, the YST expressed mRNA for TJ proteins and high incubation temperature increased ZO1 and JAM2 mRNA. This suggests that the TJ in the vasculature of the YST and intestine is affected by high incubation temperature.
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Affiliation(s)
- M Jia
- School of Animal Sciences, Virginia Tech, Blacksburg, VA 24061, USA
| | - K L Reynolds
- School of Animal Sciences, Virginia Tech, Blacksburg, VA 24061, USA
| | - E A Wong
- School of Animal Sciences, Virginia Tech, Blacksburg, VA 24061, USA.
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Short E, Owen M, Vallee E, Bolwell C, Morgan KJ. Ultrasonographic features of the regressing yolk sac of normal captive Brown kiwi chicks (Apteryx mantelli) vary with age. Vet Radiol Ultrasound 2023; 64:945-956. [PMID: 37614191 DOI: 10.1111/vru.13280] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2023] [Revised: 06/06/2023] [Accepted: 06/08/2023] [Indexed: 08/25/2023] Open
Abstract
Brown kiwi (Apteryx mantelli) are a culturally significant ratite species endemic to New Zealand. Chicks can develop diseases of the yolk sac which can be fatal if not promptly recognized and treated. Ultrasound examination of the yolk sac is an important component in the evaluation of chicks with suspected yolk sac disease. However, there are currently no reports of the normal ultrasonographic appearance of the regressing yolk sac in this species. The objective of this prospective reference interval study was to describe the normal ultrasonographic appearance of the yolk sac in brown kiwi chicks. Focused coelomic sonographic examinations were performed on 29 healthy chicks from >1 day of age until the yolk sac was completely absorbed or was <1 mL in volume. 41.6% (57/137) of yolks were round/ovoid in shape and 58.6% (80/137) had lobulated margins with invaginations. All yolks (137/137) were hyperechoic relative to adjacent coelomic structures. The heterogeneity of the echogenicity of the yolk was significantly associated with age (increased heterogeneity in younger birds) and was homogeneous, mildly heterogeneous, and moderately heterogeneous in 33% (46/138), 46% (63/138), and 21% (29/138) of all examinations respectively. Intrasac anechoic pockets were seen in 14% (20/139) of yolk sacs. The rate of yolk sac resorption slowed with age. In all examinations identifying a completely absorbed yolk sac or a yolk sac <1 mL in volume, chicks were less than 21 days old. The results of this study provide a reference of normal for the sonographic appearance of the yolk sac in captive brown kiwi chicks.
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Affiliation(s)
- Emily Short
- School of Veterinary Science, Massey University, Palmerston North, New Zealand
- Radiology department of the Massey University Veterinary Teaching Hospital, NZRadVet, Feilding, New Zealand
| | - Mark Owen
- Radiology department of the Massey University Veterinary Teaching Hospital, NZRadVet, Feilding, New Zealand
| | - Emilie Vallee
- School of Veterinary Science, Massey University, Palmerston North, New Zealand
| | - Charlotte Bolwell
- School of Veterinary Science, Massey University, Palmerston North, New Zealand
| | - Kerri J Morgan
- School of Veterinary Science, Massey University, Palmerston North, New Zealand
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Gadelha AIBB, de Oliveira MF, de Sousa ACFC, Diniz JARA, Lopes IRG, Fernandes BCC, Pereira AF, de Moura CEB. Extraembryonic membrane morphology in greater rheas ( Rhea americana americana Linnaeus, 1758). ZOOMORPHOLOGY 2023; 142:1-16. [PMID: 37360222 PMCID: PMC10027282 DOI: 10.1007/s00435-023-00602-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2022] [Revised: 01/16/2023] [Accepted: 02/27/2023] [Indexed: 03/29/2023]
Abstract
The greater rhea, Rhea americana, is a wild ratite of high scientific importance and significant and zootechnical value, especially considering the current development state of Brazilian poultry production, where research aimed at increasing the productivity of these animals has become extremely relevant. Studies concerning fetal attachments and embryonic development are paramount, as they can provide essential information concerning reproductive and nutritional animal management. However, a lack of information on greater rhea fetal morphology is noted. Therefore, the aim of the present study was to establish a standard model for fetal attachments in this species. Greater rhea eggs were incubated from 0 to 36 days, and macroscopic and microscopic embryonic attachment characterizations were performed. Histologically, all embryonic annexes exhibit germ layers, namely the ectoderm (outer layer), mesoderm (middle layer) and endoderm (inner layer). The findings indicate that greater rhea development patterns are similar to other birds.
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Affiliation(s)
- Ana Indira Bezerra Barros Gadelha
- Postgraduate Program in Animal Science, Federal Rural University of Semi-Árido, Rio Grande do Norte Mossoró, Brazil
- Department of Animal Sciences, Federal Rural University of Semi-Árido, Rio Grande do Norte Mossoró, Brazil
- Masters Program in Development and Environment, Federal Rural University of Semi-Árido, Rio Grande do Norte Mossoró, Brazil
| | - Moacir Franco de Oliveira
- Postgraduate Program in Animal Science, Federal Rural University of Semi-Árido, Rio Grande do Norte Mossoró, Brazil
| | | | - João Augusto Rodrigues Alves Diniz
- Postgraduate Program in Animal Science, Federal Rural University of Semi-Árido, Rio Grande do Norte Mossoró, Brazil
- Department of Animal Sciences, Federal Rural University of Semi-Árido, Rio Grande do Norte Mossoró, Brazil
- Doctoral Program in Development and Environment, Federal Rural University of Semi-Árido, Rio Grande do Norte Mossoró, Brazil
| | - Igor Renno Guimarães Lopes
- Postgraduate Program in Animal Science, Federal Rural University of Semi-Árido, Rio Grande do Norte Mossoró, Brazil
- Department of Animal Sciences, Federal Rural University of Semi-Árido, Rio Grande do Norte Mossoró, Brazil
- Doctoral Program in Development and Environment, Federal Rural University of Semi-Árido, Rio Grande do Norte Mossoró, Brazil
| | | | - Alexsandra Fernandes Pereira
- Postgraduate Program in Animal Science, Federal Rural University of Semi-Árido, Rio Grande do Norte Mossoró, Brazil
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Biesek J, Wlaźlak S, Adamski M. The biological value of hatching eggs of broiler chicken in the early-mid incubation period based on physicochemical and morphological features. Poult Sci 2023; 102:102689. [PMID: 37116284 PMCID: PMC10160584 DOI: 10.1016/j.psj.2023.102689] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2022] [Revised: 03/28/2023] [Accepted: 03/28/2023] [Indexed: 04/03/2023] Open
Abstract
The study aimed to assess various quality characteristics (physical, morphologic, mechanical) of hatching eggs during the early-mid incubation period. Hatching eggs (1,200) were bought from a broiler Ross 308 breeder flock. Before incubation, 20 eggs were analyzed for dimensions and morphologic composition. Eggs (1,176) were incubated for 21 d. Hatchability was analyzed. On d 1, 2, 4, 6, 8, 10, and 12, eggs were collected (n = 20). The eggshell surface temperature and water loss were measured. The eggshell strength and thickness and the vitelline membrane strength were analyzed. The pH of thick albumen, amniotic fluid, and yolk were determined. The viscosity and lysozyme activity were studied for the thick albumen and amniotic fluid. Water loss was proportional and significantly different between incubation days. The yolk vitelline membrane strength highly depended on incubation days, decreasing steadily within the first 2 d (R2 = 0.9643). The albumen pH decreased from d 4 till d 12 of incubation, whereas the yolk pH first increased from d 0 to d 2 before a decline on d 4. Albumen viscosity was highest on d 6. There was a strong dependence of viscosity decrease with increasing shear rate (R2 = 0.7976). On the first day of incubation, the highest lysozyme hydrolytic activity was demonstrated (33,790 U/mL) compared to the activity from the amniotic fluid (8-12 d). From d 6, lysozyme activity decreased to 70 U/mL (d 10). On d 12, amniotic fluid lysozyme activity increased by over 6,000 U/mL compared to d 10. The lysozyme hydrolytic activity was lower in the amniotic fluid (d 8-12) compared to the thick albumen (0-6 d) (P < 0.001). The embryo's protective barriers are changed, and the fractions are hydrated during incubation. It could be concluded that the lysozyme is transferred from the albumen to the amniotic fluid due to its activity.
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7
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Reno KE, Cloft SE, Wong EA. Expression of genes associated with apoptosis in the residual yolk sac during the peri-hatch period of broiler chicks. Poult Sci 2022; 101:101966. [PMID: 35760000 PMCID: PMC9241046 DOI: 10.1016/j.psj.2022.101966] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2021] [Revised: 04/19/2022] [Accepted: 05/13/2022] [Indexed: 11/07/2022] Open
Abstract
The yolk sac (YS) consists of the yolk and the surrounding YS tissue, which provides essential nutrients and physiological functions for the developing embryo. After the YS is internalized into the abdominal cavity of the embryonic chick, the YS starts to degrade. Apoptosis, or programmed cell-death, is speculated to be the mechanism behind degradation of the YS. The objective of this study was to determine if degradation of the YS tissue was mediated by apoptosis during the perihatch period. The YS tissue was collected from broiler chicks from embryonic d 17 to d 7 posthatch. The mRNA abundance of genes that are involved in the regulation, initiation, and execution of apoptosis were analyzed by qPCR. The mRNA for Bcl2, Bcl2L11, cytochrome C and caspases 3, 6, 7, 8, 9, and 18 all showed a linear response from embryonic d 17 to d 7 posthatch. To confirm the role of apoptosis in the degradation of the YS tissue, a DNA fragmentation assay was performed. Degradation of genomic DNA in the YS tissue started on day of hatch. The characteristic ladder of oligonucleosomal-sized DNA fragments was observed on d 3, 5, and 7 posthatch. The combined gene expression and DNA fragmentation results demonstrate that degradation of the YS posthatch is mediated by apoptosis.
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Meng Y, Qiu N, Guyonnet V, Mine Y. Omics as a Window To Unravel the Dynamic Changes of Egg Components during Chicken Embryonic Development. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2021; 69:12947-12955. [PMID: 34709815 DOI: 10.1021/acs.jafc.1c05883] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Chicken egg, as a completely aseptic and self-sufficient biological entity, contains all of the components required for embryonic development. As such, it constitutes not only an excellent model to study the mechanisms of early embryo nutrition and disease origin but can also be used to develop egg-based products with specific applications. Different omics disciplines, like transcriptomics, proteomics, and metabolomics, represent promising approaches to assess nutritional and functional molecules in eggs under development. However, these individual molecules do not act in isolation during the dynamic embryogenic process (e.g., migration, transportation, and absorption). Unless we integrate the information from all of these omics disciplines, there will remain an unbridged gap in the systematic and holistic assessment of the information from one omics level to the other. This integrative review of the dynamic molecular processes of the different chicken egg components involved in embryo development describes the critical interplay between the egg components and their implications in immunity, hematopoiesis, organ formation, and nutrient transport functions during the embryonic process.
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Affiliation(s)
- Yaqi Meng
- Key Laboratory of Environment Correlative Dietology, Ministry of Education, College of Food Science and Technology, Huazhong Agricultural University, Wuhan, Hubei 430070, People's Republic of China
| | - Ning Qiu
- Key Laboratory of Environment Correlative Dietology, Ministry of Education, College of Food Science and Technology, Huazhong Agricultural University, Wuhan, Hubei 430070, People's Republic of China
| | - Vincent Guyonnet
- FFI Consulting, Limited, 2488 Lyn Road, Brockville, Ontario K6V 5T3, Canada
| | - Yoshinori Mine
- Department of Food Science, University of Guelph, Guelph, Ontario N1G 2W1, Canada
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Zhu Y, Zhao J, Wang C, Zhang F, Huang X, Ren Z, Yang X, Liu Y, Yang X. Exploring the effectiveness of in ovo feeding of vitamin C based on the embryonic vitamin C synthesis and absorption in broiler chickens. J Anim Sci Biotechnol 2021; 12:86. [PMID: 34340712 PMCID: PMC8330104 DOI: 10.1186/s40104-021-00607-w] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2021] [Accepted: 06/01/2021] [Indexed: 12/29/2022] Open
Abstract
BACKGROUND Many researches about in ovo feeding (IOF) of vitamin C (VC) are gradually carried out to explore physiological development in chicken, but little studies focus on VC synthesis capacity of the embryo itself, the selection of injection site and the effectiveness of IOF of VC. This study aims to explore the above problems. RESULTS Kidney and yolk sac were the main organs for VC synthesis and L-gulonolactone oxidase (GLO) expression was lower during pre-hatch development than that during post-hatch development. Sodium-dependent vitamin C transporter 1 (SVCT1) expression was increased continuously in yolk sac from embryonic age 19 (E19) to post-hatch day 1 (D1) and in intestine (duodenum, jejunum and ileum) from E17 to D1. Plasma VC content was higher at D1 than that at D21 and D42. IOF of VC significantly reduced GLO expression in liver, kidney and yolk sac as well as SVCT1 expression in duodenum, jejunum and ileum, but increased the VC content in plasma, brain, kidney and liver. In addition, IOF of VC obviously reduced the embryonic morality and increased the hatchability under heat stress. CONCLUSIONS This study suggested that IOF of VC at E11 in yolk was effective for embryonic VC supplementation. These findings provide a theoretical reference about the method of embryonic VC supplementation and effective methodology on embryonic VC nutrition in broiler chickens.
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Affiliation(s)
- Yufei Zhu
- College of Animal Science and Technology, Northwest A&F University, Yangling, Shaanxi China
| | - Jianfei Zhao
- College of Animal Science and Technology, Northwest A&F University, Yangling, Shaanxi China
| | - Chenxu Wang
- College of Animal Science and Technology, Northwest A&F University, Yangling, Shaanxi China
| | - Fei Zhang
- College of Animal Science and Technology, Northwest A&F University, Yangling, Shaanxi China
| | - Xinhuo Huang
- Nano Vitamin Engineering Research Center of Shaanxi Province, Xi’an, Shaanxi China
| | - Zhouzheng Ren
- College of Animal Science and Technology, Northwest A&F University, Yangling, Shaanxi China
| | - Xin Yang
- College of Animal Science and Technology, Northwest A&F University, Yangling, Shaanxi China
| | - Yanli Liu
- College of Animal Science and Technology, Northwest A&F University, Yangling, Shaanxi China
| | - Xiaojun Yang
- College of Animal Science and Technology, Northwest A&F University, Yangling, Shaanxi China
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10
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Starck JM, Stewart JR, Blackburn DG. Phylogeny and evolutionary history of the amniote egg. J Morphol 2021; 282:1080-1122. [PMID: 33991358 DOI: 10.1002/jmor.21380] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2020] [Revised: 05/07/2021] [Accepted: 05/12/2021] [Indexed: 01/02/2023]
Abstract
We review morphological features of the amniote egg and embryos in a comparative phylogenetic framework, including all major clades of extant vertebrates. We discuss 40 characters that are relevant for an analysis of the evolutionary history of the vertebrate egg. Special attention is given to the morphology of the cellular yolk sac, the eggshell, and extraembryonic membranes. Many features that are typically assigned to amniotes, such as a large yolk sac, delayed egg deposition, and terrestrial reproduction have evolved independently and convergently in numerous clades of vertebrates. We use phylogenetic character mapping and ancestral character state reconstruction as tools to recognize sequence, order, and patterns of morphological evolution and deduce a hypothesis of the evolutionary history of the amniote egg. Besides amnion and chorioallantois, amniotes ancestrally possess copulatory organs (secondarily reduced in most birds), internal fertilization, and delayed deposition of eggs that contain an embryo in the primitive streak or early somite stage. Except for the amnion, chorioallantois, and amniote type of eggshell, these features evolved convergently in almost all major clades of aquatic vertebrates possibly in response to selective factors such as egg predation, hostile environmental conditions for egg development, or to adjust hatching of young to favorable season. A functionally important feature of the amnion membrane is its myogenic contractility that moves the (early) embryo and prevents adhering of the growing embryo to extraembryonic materials. This function of the amnion membrane and the liquid-filled amnion cavity may have evolved under the requirements of delayed deposition of eggs that contain developing embryos. The chorioallantois is a temporary embryonic exchange organ that supports embryonic development. A possible evolutionary scenario is that the amniote egg presents an exaptation that paved the evolutionary pathway for reproduction on land. As shown by numerous examples from anamniotes, reproduction on land has occurred multiple times among vertebrates-the amniote egg presenting one "solution" that enabled the conquest of land for reproduction.
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Affiliation(s)
- J Matthias Starck
- Department of Biology, Ludwig-Maximilians-University Munich, Planegg-Martinsried, Germany
| | - James R Stewart
- Department of Biology, Ludwig-Maximilians-University Munich, Planegg-Martinsried, Germany.,Department of Biological Sciences, East Tennessee State University, Johnson City, Tennessee, USA
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Carter AM. T. Thomson Flynn and the monotreme egg from oocyte maturation to germ layer formation. J Morphol 2021; 282:1015-1023. [PMID: 33393100 DOI: 10.1002/jmor.21319] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2020] [Revised: 12/31/2020] [Accepted: 01/01/2021] [Indexed: 12/14/2022]
Abstract
Knowledge of oocyte development and the early differentiation of the germ layers in monotremes stems largely from two articles by J. P. Hill and T. Thomson Flynn. The completeness of their account was due to the large series of echidna ovaries and eggs collected on Tasmania by Flynn, an Australian biologist of whom a brief account is given. A striking finding in the oocyte and early embryo of monotremes was the presence of a latebra connected to the yolk bed beneath the germinal disc as described in birds and several reptiles. A further resemblance was the presence early in vitellogenesis of a striate zone beneath the zona pellucida. Cleavage resulted first in a lens-shaped blastodisc encircled by cells called vitellocytes that later fused to form a germ-ring. The blastodisc gave rise to a blastoderm that eventually became unilaminar but comprised two cell types identified as ectoderm and primitive endoderm. Eventually these segregated into two layers and formed a blastula. This sequence resembled that in marsupials except there was no obvious distinction between future embryonic and extra-embryonic regions. As the blastoderm extended over the surface of the yolk, it was preceded by the germ-ring that eventually played a role in forming the yolk navel. This was a unique feature of monotreme development. It is shown that Flynn played an important role in analysis of the material as well as in its collection.
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Affiliation(s)
- Anthony M Carter
- Cardiovascular and Renal Research, Institute of Molecular Medicine, University of Southern Denmark, Odense, Denmark
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12
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Blackburn DG, Stewart JR. Morphological research on amniote eggs and embryos: An introduction and historical retrospective. J Morphol 2021; 282:1024-1046. [PMID: 33393149 DOI: 10.1002/jmor.21320] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2020] [Revised: 12/31/2020] [Accepted: 01/01/2021] [Indexed: 12/21/2022]
Abstract
Evolution of the terrestrial egg of amniotes (reptiles, birds, and mammals) is often considered to be one of the most significant events in vertebrate history. Presence of an eggshell, fetal membranes, and a sizeable yolk allowed this egg to develop on land and hatch out well-developed, terrestrial offspring. For centuries, morphologically-based studies have provided valuable information about the eggs of amniotes and the embryos that develop from them. This review explores the history of such investigations, as a contribution to this special issue of Journal of Morphology, titled Developmental Morphology and Evolution of Amniote Eggs and Embryos. Anatomically-based investigations are surveyed from the ancient Greeks through the Scientific Revolution, followed by the 19th and early 20th centuries, with a focus on major findings of historical figures who have contributed significantly to our knowledge. Recent research on various aspects of amniote eggs is summarized, including gastrulation, egg shape and eggshell morphology, eggs of Mesozoic dinosaurs, sauropsid yolk sacs, squamate placentation, embryogenesis, and the phylotypic phase of embryonic development. As documented in this review, studies on amniote eggs and embryos have relied heavily on morphological approaches in order to answer functional and evolutionary questions.
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Affiliation(s)
- Daniel G Blackburn
- Department of Biology and Electron Microscopy Center, Trinity College, Hartford, Connecticut, USA
| | - James R Stewart
- Department of Biological Sciences, East Tennessee State University, Johnson City, Tennessee, USA
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Blackburn DG. Functional morphology, diversity, and evolution of yolk processing specializations in embryonic reptiles and birds. J Morphol 2020; 282:995-1014. [PMID: 32960458 DOI: 10.1002/jmor.21267] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2020] [Revised: 08/24/2020] [Accepted: 09/08/2020] [Indexed: 12/21/2022]
Abstract
Evolution of the terrestrial, amniotic egg of vertebrates required new mechanisms by which yolk material could be processed for embryonic use. Recent studies on each of the major extant reptile groups have revealed elaborate morphological specializations for yolk processing, features that differ dramatically from those of birds. In the avian pattern, liquid yolk is housed in a yolk sac whose endodermal lining absorbs and digests yolk material and sends resultant nutrients into the blood circulation. In snakes, lizards, turtles, and crocodilians, as documented herein, the yolk sac becomes invaded by endodermal cells that proliferate and phagocytose yolk material. Blood vessels then invade, and the endodermal cells become arranged around them, forming elongated "spaghetti-like" strands that fill the yolk sac cavity. This pattern provides an effective means by which yolk material is cellularized, digested, and transported by vitelline vessels to the developing embryo. Phylogenetically, the (non-avian) "reptilian" pattern was ancestral for sauropsids and was modified or replaced in ancestors to birds. This review postulates that evolution of the "avian" pattern involved increased reliance on extracellular digestion of yolk, allowing embryonic development to occur more rapidly than in typical reptiles. Comparative studies of yolk processing that draw on morphological, biochemical, molecular approaches are needed to explain how and why the "reptilian" pattern was replaced in birds or their archosaurian ancestors.
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Affiliation(s)
- Daniel G Blackburn
- Department of Biology, Electron Microscopy Center, Trinity College, Hartford, Connecticut, USA
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