<div>Doxycycline HCL is a member of the tetracycline family of antibiotics. Extensive use of the antibiotic (Doxycycline HCl) in poultry for treatment of various bacterial diseases is increasing with time. The current trail was therefore formulated and conducted to investigate the embryotoxic aspects of Doxycycline HCl on Gallus domesticus. Different doses of Doxycycline HCl (0.1, 0.5, 1.0, 1.5, 2.0 and 3.0&micro;g/100&micro;l distilled water/egg in six experimental groups (B, C, D, E, F and G respectively) were inoculated into the yolk sac of 60 eggs (10 eggs per group) before incubation. Group A was control group (injected with distilled water). Chick embryos were studied at 12th day of incubation. The results showed significant (p&lt;0.05) increase in death rate of chick embryos with increasing dose. At the end of the trial, morphometric measurements viz., wet body weight, crown rump length, eye diameter, beak length, neck length, anterior posterior head diameter, humerus length, radius and ulna length, metacarpus length, femur length, fibula length and metatarsus length were also noted and compared to untreated group. A significant (p&lt;0.05) difference was observed among all quantitative parameters in experimental groups compared with negative control group except metacarpus and metatarsus length which showed non-significant (p&gt;0.05) difference. Additionally, qualitative malformations like microcephaly, hydrocephaly, edema, hematoma, abnormal body coloration, anophthalmia, microphthalmia, deformed beak, agnathia, wry neck, micromelia, amelia, meromelia, damaged auditory meatus, omphalocele and ectopia cordis were noted in experimental groups as compared with untreated groups.&nbsp;</div>


<div>Embryotoxicity of Doxycycline HCl in <em>Gallus domesticus:</em> Morphometric Changes and External Anomalies</div>


<div><strong>Background: </strong>Vitamin A has potentially harmful effects on the development of chick embryos even at very low dose concentration. Vitamin A different doses cause embryotoxic and teratogenic effects on the developing of the chick embryo. Hence, due to teratogenicity of this vitamin it can be used with utmost caution during pregnancy. &nbsp; &nbsp; &nbsp;<br />
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<strong>Methods:</strong> Fertile chicken eggs (obtained from local hatchery) were injected with three doses of Vitamin A (15 IU/ml, 30 IU/ml, 75 IU/ml) into the center of the egg yolk. Morphometric parameters as mortality rate, body weight (g), crown rump length (mm) of embryo and Frequency % of different anomalies gross malformations were measured. Whole chicken samples were taken by 4<sup>th</sup>, 8<sup>th</sup> and 18th incubation day. Daam, Hox and Tbx genes expression profile were analyzed.<br />
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<strong>Result:</strong> Dose-dependent defects and embryo lethality in the chick embryos developed when exposed to higher concentrations. Our study record for the first time the duplication in the heart, brain and eye. Also showed duplication of the neck forming S-shaped showed in some malformed chick embryos. The three investigated genes showed different fluctuations confirming the malformations detected.</div>


Embryotoxicity of Doxycycline HCl in Gallus domesticus: Morphometric Changes and External Anomalies

Impact of Vitamin A on the Expression Profile of Development-Controlling Genes in Chick Embryos