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Developmental Stages of Embryo in Relevance with Endocrine Glands in Japanese Quail (Coturnix coturnix japonica)
Dr. Jyoti S. Ramteke
Japanese quails are produced mainly for their eggs and meat. Quail belong, along with chickens, pheasants and partridges to the Family Phasianaidea of Order Galliformes of the Class Aves of the Animal Kingdom. Species or subspecies of the genus Coturnix are native to all continents except the Americas. One of them Coturnix coturnix or common quail are migratory birds of Asia. The Japanese quail remains one of the favored animal models in developmental biology and is being used as part of the quail chick chimeric methodology. As the popularity of this animal is growing it was necessary to study the developmental stages of the bird. This is especially important as this knowledge will help in boosting the production as well as maintaining the livestock. The appearance of various developmental features after specific periods of incubation make possible to attribute quail development.
Egg weight, Egg Volume , Egg Weight Loss and Embryo Weight
The weight loss of egg after incubation is an important parameter during incubation. It has been used to estimate gas exchange and has been correlated with the rate of embryonic metabolism and development. In view of the importance of this the data pertaining to egg weight, egg volume and egg weight loss was studied and based on this data, it can be concluded that the percent weight loss of egg of Japanese quail as a function of time shows variation from 5.5 to 13.2%. Since, all the specimens showed weight loss between the above mentioned scale, it can be concluded that the weight loss in Japanese quail is marginal. There is gradual increase in the emryo weight of Japanese quail up to 8th day and beyond which, the rate of weight increase is noticeably high.
Morphological Study : The observations made on the successive days indicated following morphological characteristics of the Japanese quail. The developmental stages were studied from Day 1 to Day 17.
Histological Study: The Endocrine system consists of various glands and nodes which secrete hormones. The importance of these hormones lies in the fact that they travel in the blood to activate target cells. In view of the importance of endocrine glands, their development in Japanese quail was assessed on the basis of histological studies. The specific findings with respect to the development of endocrine glands in Japanese quail are, the adrenal glands start developing from the 4th day and functions from 10th day of embryo, Ovary formation starts from the 5th day embryo and appears completely on 8th day embryo. Testis was observed from the 4th to 7th day embryo. Thyroid gland formation starts from 4th day of embryo and functions from the 8th day embryo. The pancreatic buds start developing from day 3 to day 9 of incubation.