The Veterinary Manual was first published in as a service to the community. The legacy of this great resource continues in the online and mobile app versions today. This site complies with the HONcode standard for trustworthy health information: verify here. Common Veterinary Topics. Videos Figures Images Quizzes. You must have JavaScript enabled in your browser to utilize the functionality of this website. Save For Later Print. The reproductive system of the female chicken is in two parts: the ovary and oviduct.
Unlike most female animals, which have two functioning ovaries, the chicken usually has only one. The right ovary stops developing when the female chick hatches, but the left one continues to mature. The ovary is a cluster of sacs attached to the hens back about midway between the neck and the tail. It is fully formed when the chicken hatches and contains several thousand tiny ova, each ovum within its own follicle. As the female reaches maturity, these ova develop a few at a time into yolks.
As the ovum develop and get larger, you can see the stigma line clear line on each ovum. This is where the yolk is released. On the surface of every egg yolk there can be seen a tiny, whitish spot called the blastodisc. This contains a single female cell. This difference could be due to breed variation. The mean vagina weights 1. Furthermore, the length and width of vagina in the present study are shorter than those of adult ISA-brown chicken, 28 in ostrich 20 and in turkey.
This study in addition to its contribution to the knowledge of comparative avian anatomy up to genotype level, has also established a comparative baseline data for further comparative gross and morphometric reproductive studies in these genotypes of Nigerian local chickens.
This is an open access article distributed under the terms of the, which permits unrestricted use, distribution, and build upon your work non-commercially. Withdrawal Guidlines. Publication Ethics. Withdrawal Policies Publication Ethics. Home JDVAR Gross morphological and morphometric studies of oviduct in three genotypes of nigerian indigenous laying chickens.
Journal of. Research Article Volume 5 Issue 4. Keywords: morphology, morphometry, genotypes, local chicken. NoF, normal feather chicken; Na, naked neck chicken; FF, frizzle feather chicken. Gross morphology of oviduct The oviduct in the laying NoF Plate 1 , Na Plate 2 and FF Plate 3 genotypes appeared to be long, less convoluted, highly vascular tube and occupied the most left side of celom, with five morphologically distinct regions; infundibulum, magnum, isthmus, uterus, and vagina.
Infundibulum In all the three species, the infundibulum was the first segment of the oviduct, and further divided into two morphologically distinct areas: the funnel and the neck. Magnum The magnum was the most convoluted part of the oviduct in all the three laying species but most coiled in the NoF than in the remaining two species. Isthmus The isthmus was comparatively narrow than magnum and uterus.
Uterus The uterus was divisible into the cranial narrow tubular part called pars minor uteri and the main pouch like part called the pars major uteri. Vagina The vagina was the last region of the oviduct. Egg production of two Nigerian local chicken ecotypes under improved management. March , University of Calabar, Nigeria; Genetic distinctness of African, Asian and South American local chickens. Anim Genet. Productive performance and occurrence of Major genes in the Nigerian local chicken.
Nigerian Journal of Genetics. International Journal of Poultry Science. Effects of strain and age on egg quality characteristics of two different strains of layer chickens kept in cages in Derived Savannah Zone of Nigeria. Early maternal effects and antibacterial immune factors in the eggs, nestlings and adults of the barn swallow.
Journal of Evolutionary Biology. Bradley OC, Grahame T. The Structure of the Fowl. Edinburgh: Oliver and Boyd; Fitzgerald TC. The Coturnix Quail Anatomy and Histology. Genetic variation in the reproductive performance of the Nigerian indigenous chicken. Tropical Animal Production and Investment. Modellling Growth in Seven chicken genotypes. Nigerian Journal of Animal Production.
Semen quality traits of seven strains of chickens raised in the humid tropics. Gene segregation effects on fertility and hatchability of pure and crossbred chicken genotypes in the humid tropics. Wekhe SN. Susceptibility of indigenous Nigerian and exotic Harco chickens to fowl typhoid infection.
Tropical Veterinarian. Google Maps. Wilson GW. Zinc is the co-enzyme of carbonic anhydrase and any conditions resulting in Zn deficiency can lead to problems associated with egg shell formation. The shell of an egg contains openings or pores. The function of these pores is to provide for the gaseous exchange during incubation and embryonic development. The developing embryo requires oxygen and gives off carbon dioxide. When the egg is first laid most of the pores are closed.
However, as the egg ages more and more pores open up. The cuticle deposited on the outer shell is composed of organic material and water and blocks the pores. The vagina is about 12 centimetres in length. While not known for sure, it may have the function of adding pigment to the outer shell to provide the egg with its colour. The egg is held in the cloaca immediately prior to being laid. It may be in the cloaca for several hours, but usually is held there for a much shorter time.
Although the egg usually enters this organ small end first, it usually rotates there to be laid by the large end first. However, if the bird should be startled at this time the egg may be forcibly expelled small end first. The formation of an egg is a very complex activity during which much can go wrong.
The quality of the final product, the egg as it is laid, is influenced by both genetic and management factors. Notice: JavaScript is required for this content. Skip to content Search. The Reproductive System The avian reproductive system is heterosexual and requires both a male and a female, each to contribute half of the genetic constitution of the offspring.
Male reproductive system. The urinary and reproductive organs of the male chicken. Deferent duct The deferent duct transports the sperm from the testes where they are formed to the cloaca from which they enter the oviduct of the female when mating.
Testes and sperm In the testes very twisted tubes called seminiferous tubules are found. Female reproductive system The female reproductive system in the domestic fowl consists of the ovary and the accompanying oviduct. Ovary The ovary consists of a mass of yellowish, rounded objects called follicles, each containing an ovum or yolk. It is possible to find five stages of development in the active ovary: Primary follicles — follicles that have not yet commenced to grow Growing follicles Mature follicles — follicles ready or nearly so for release Discharged follicles — where the yolk has just been released Atretic follicles — those from which the yolk has been released some time ago Yolk It takes approximately 10 days for a yolk to develop from the very small to the normal size found in eggs and during this time it is contained in the follicle.
Ovary and oviduct. Oviduct The function of the oviduct is to produce the albumen, shell membranes and the shell around the yolk to complete the egg. The oviduct consists of five distinct parts or sections, each having different functions: Infundibulum or funnel : located adjacent to the ovary and with long segments enclosing the ovary, the infundibulum collects the yolk after its release from the follicle as a funnel and directs it into the oviduct. This section has very thin walls and is centimetres long.
Fertilisation of the ovum by the male sperm occurs here. Isthmus: at about 12 centimetres in length, it secretes some albumen and the shell membranes. Androgen, oestrogen and progesterone In addition to the production of eggs, the female reproductive system also produces hormones that aid in the control of body functions. The normal egg consists of the following major parts: Yolk carrying the ovum — produced by the ovary Albumen or white — produced mainly in the magnum Shell membranes — produced in the isthmus Shell — produced in the uterus or shell gland The ovary and yolk formation The ovary is attached to the abdominal cavity wall by the meso-ovarian ligament.
Ovulation The release of the yolk the process of ovulation , is the major controlling factor influencing the subsequent steps in the formation and laying of the egg.
Sexual maturity Sexual maturity is reached when the hen lays the first egg in her life. Initiation of ovulation The controlling mechanism setting the time of the day for the first ovulation is not fully understood. Clutches Eggs laid on successive days are called a clutch. Egg formation time The time taken from ovulation until when the egg passes through the vent varies with individuals within the range of 23 to 26 hours.
Ovulation time Hens that produce long clutches release the yolk very shortly after first light whether natural or artificial light. Laying pattern When pullets first commence to lay, their hormonal and other controlling systems have not yet reached a state of balance.
Oviduct The other components of the egg are the albumen, the shell membranes and the shell, and are produced by different segments of the oviduct. These segments are: Infundibulum Magnum or ampulla Isthmus Uterus or shell gland Vagina Cloaca In the egg laying hen the oviduct is a tube like organ that consists of the previously named segments with one end lying adjacent to the ovary and the other entering the vent.
Infundibulum This segment is funnel-shaped and lies adjacent to the ovary. Magnum or ampulla. There are two shell membranes: The inner shell membrane — laid down first The outer shell membrane — laid down last and about three times the thickness of the inner membrane The isthmus takes approximately 75 minutes to carry out its tasks.
Uterus shell gland and eggshell quality The uterus is a relatively short, bulbous gland up to 12 centimetres in length.
The shell of an egg is formed in two layers: Mammillary layer — a sponge like layer composed of soft calcite crystals CaCO3. This layer is the inner layer. Palisade layer — formed of columns of hard calcite crystals; the longer the columns the stronger the shell.
This layer is the outer layer of the egg.
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