BrokenWing Chronicles
The female reproductive system
The female reproductive system is unique in birds. In most birds, the hen only has a left ovary and oviduct. However, two fully developed ovaries are usually present in birds of prey and the kiwi. Two oviducts may occur in birds of prey. In normal parrots and softbills, there is usually only a left ovary and oviduct. The ovary contains all of the cells that can turn into eggs. When ovulation occurs, the egg cell and yolk are released from the ovary. Since hens produce eggs, and do not develop the babies inside the uterus, as mammals do, the oviduct is the organ that receives the egg, and then applies the egg white, membranes and shell. There are five portions to the oviduct and each performs a different function. They are the infundibulum, which receives the egg after ovulation. This is where fertilization usually occurs. Sometimes a hen will lay eggs without a male being present, and in this case, the eggs will be infertile. Chicken eggs purchased at the grocery store are infertile eggs.
The next portion of the oviduct is the magnum. It is in this area that the bulk of the egg-white protein is added. The egg travels next into the isthmus where egg membranes are produced and calcification of shell begins. The next portion of the oviduct is called the uterus, but it is nothing like the uterus of a mammal. The uterus is also called the shell gland, as this is where the shell is put on the egg. The final portion of the oviduct is called the *bleep*, and it is here where the sperm are stored in the hen once copulation has occurred. It takes about 25 hours for the egg to travel down the oviduct. The oviduct terminates in the urodeum.
Unlike the hen's reproductive tract, the male usually has two functional testicles. However, they are located up inside the body near the kidneys, and are not found externally as they are in mammals. This is why most birds cannot be sexed by looking at the external characteristics of it, because the testicles or ovary are inside. Some birds have characteristics that identify it as male or female, such as different coloration of feathers. Eclectus parrots are an extreme example of this, as hens are predominantly red and purple and males are predominantly green. Other birds have more subtle differences. Birds that can be visually sexed are called sexually dimorphic. Monomorphic birds cannot be sexed by sight and must be sexed by chromosome analysis, DNA analysis or by endoscopy.
A Link
http://education.vetmed.vt.edu/curriculum/vm8054/labs/Lab29/EXAMPLES/EXHENEGG.HTMTo see the fimbriae of the avian oviduct
http://education.vetmed.vt.edu/curriculum/vm8054/labs/Lab29/EXAMPLES/EXFIMBRA.HTMInfundibulum
http://education.vetmed.vt.edu/curriculum/vm8054/labs/Lab29/EXAMPLES/EXINFDIB.HTMMagnum
http://education.vetmed.vt.edu/curriculum/vm8054/labs/Lab29/EXAMPLES/EXMAGNUM.HTMOviduct
http://education.vetmed.vt.edu/curriculum/vm8054/labs/Lab29/EXAMPLES/EXAVISTH.HTMShell Gland
http://education.vetmed.vt.edu/curriculum/vm8054/labs/Lab29/EXAMPLES/EXSHELL.HTM*bleep*
The last portion of the tube is the *bleep*. This a muscular tube through which the egg is expelled to the outside world. The folds of the mucosa are short, and the lining is a tall columnar epithelium, again intermittently ciliated.
Near the junction of the *bleep* and the shell gland, there are deep glands lined with simple columnar epithelium. These are the sperm host glands, so called because they can store sperm for long periods of time (10 days to 2 weeks!). When an egg is laid, some of these sperm can be squeezed out of the glands into the lumen of the tract, whence they will migrate farther up to fertilize another egg. This is one of the really remarkable things about birds; they sperm remain viable at body temperature.
BrokenWing
