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The archenteron initially forms, and the mesoderm splits into two layers: the first attaches to the body wall or ectoderm, forming the parietal layer and the second surrounds the endoderm or alimentary canal forming the visceral layer. The space between the parietal layer and the visceral layer is known as the coelom or body cavity.
The epidermis is either a syncytium or a single layer of cells, and is covered by a thick collagenous cuticle. The cuticle is often of a complex structure and may have two or three distinct layers. Underneath the epidermis lies a layer of longitudinal muscle cells. The relatively rigid cuticle works with the muscles to create a hydroskeleton ...
They function as the main blood vessels, although they are side-by-side rather than upper and lower. However, they are lined with mesothelium, like the coelomata and unlike the blood vessels of other annelids. Leeches generally use suckers at their front and rear ends to move like inchworms. The anus is on the upper surface of the pygidium. [15]
Dirofilaria immitis, also known as heartworm or dog heartworm, is a parasitic roundworm that is a type of filarial worm, a small thread-like worm, and which causes dirofilariasis. It is spread from host to host through the bites of mosquitoes. Four genera of mosquitoes transmit dirofilariasis, Aedes, Culex, Anopheles, and Mansonia. [2]
In the duodenum, a single rhabditiform larva hatches from each of the ingested eggs. The larvae then penetrate the mucosa and submucosa and enter the venules or lymphatic vessels. From there, the larvae then pass through the heart to enter the pulmonary circulation. The larvae then break through the walls of the pulmonary capillaries to enter ...
Whole blood with microfilaria worm, giemsa stain. L. loa worms have a simple structure consisting of a head (which lacks lips), a body, and a blunt tail. The outer body of the worm is composed of a cuticle with three main layers made up of collagen and other compounds which aid in protecting the nematodes while they are inside the digestive system of their host.
The two main blood vessels furnish smaller vessels to supply the parapodia and the gut. Blood flows forward in the dorsal vessel, above the gut, and returns down the body in the ventral vessel, beneath the gut. The blood vessels themselves are contractile, helping to push the blood along, so most species have no need of a heart.
Toxocara canis (T. canis, also known as dog roundworm) is a worldwide-distributed helminth parasite that primarily infects dogs and other canids, but can also infect other animals including humans. [ 1 ] [ 2 ] The name is derived from the Greek word toxon 'bow, quiver' and the Latin word caro 'flesh'. [ 3 ]