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Nematode sperm is thought to be the only eukaryotic cell without the globular protein G-actin. [49] Eggs may be embryonated or unembryonated when passed by the female, meaning their fertilized eggs may not yet be developed. A few species are known to be ovoviviparous. The eggs are protected by an outer shell, secreted by the uterus.
These eggs have a strong shell that protects them against a range of environmental conditions. The eggs can therefore survive in the environment for many months or years. Many of the worms referred to as helminths are intestinal parasites. An infection by a helminth is known as helminthiasis, helminth infection, or intestinal worm infection ...
The direct counting of nematode eggs in feces is the method of choice for yearling animals, whereas in adult animals it may yield high variability due to a cow's immunity and low egg output. [41] Other biochemical methods have been developed to help more accurately diagnose O. ostertagi parasitism. These include the determination of specific ...
The eggs measure 50 to 60 μm by 20 to 30 μm, and have a thick shell flattened on one side. [18] The small size and colourlessness of the eggs make them invisible to the naked eye, except in barely visible clumps of thousands of eggs. Eggs may contain a developing embryo or a fully developed pinworm larva. [18] The larvae grow to 140–150 μm ...
C. elegans under a microscope. Numerous gut granules are present in the intestine of C. elegans, the functions of which are still not fully known, as are many other aspects of this nematode, despite the many years that it has been studied. These gut granules are found in all of the Rhabditida orders.
Eggs are excreted in the urine via the renal pelvis. These eggs are oval to cylindrical, yellow-brown, thick-walled, with a rough, knobbed surface, and 71-84 × 45-52 μm in size. [46] The eggs embryonate within two weeks to three months, depending on the ambient temperature, and then become infectious to intermediate hosts. [47]
The animal produces antibodies against the protein which circulate in the blood. When the Barber's pole worm drinks the blood the antibodies attach to its stomach lining, preventing digestion and starving the animal. Following this, the worm produces fewer eggs and eventually dies off. [10]
The release of oocytes (eggs) in female worms does not depend upon the presence of a male worm, although they may attract male worms using unidentified pheromones. [8] The first larval stage, microfilariae , are 300 μm in length and unsheathed, meaning that when they mature into microfilariae, they exit from the envelope of the egg.