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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.
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 ...
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 ...
Fertile egg as can be seen in a microscope Fertile egg in human faeces (detail) Infertile egg. Ascaris lumbricoides is characterized by its great size. Males are 2–4 mm (0.08–0.2 in) in diameter and 15–31 cm (5.9–12 in) long. The male's posterior end is curved ventrally and has a bluntly pointed tail.
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.
Egg formation in M. javanica has been studied in detail, [22] and is similar to egg formation in the well studied, free-living nematode Caenorhabditis elegans. [23] Embryogenesis has also been studied, and the stages of development are easily identifiable with a phase contrast microscope following preparation of an egg mass squash.
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.
The nematode infects fowl of all ages, but the greatest degree of damage is often found in birds under 12 weeks of age. Heavy infection is the major cause of weight depression and reduced egg production in poultry husbandry. In severe infections, intestinal blockage can occur and causing haemorrhagic enteritis.