Test: Ascaris - 2 (Old NCERT) - NEET MCQ

There is a small number of cells in the pharynx, of the 60 cells in the pharynx, 20 are muscle cells of 8 anatomical types, 1 of cell bodies, 20 are neurons of 14 anatomical types, and the rest are structural and glandular cells.

In marine nematodes, the excretory system consists of one or two large renette gland cells lying ventrally in the pseudocoel near the junction of the pharynx and intestine, a duct arises from each renette cell, these ducts join and open by an excretory pore mid-ventrally.

The nerve ring receives sensory input from the anterior tip of the animal by means of six nerve bundles, all nerve fibers of which have centrally located cell bodies. The anterior sensory structures are classically divided into two types, papilIary and amphidial, and are assumed responsible for mechano- and chemoreception, respectively.

They are typically large worms upto about 40 cm long characterized by a mouth surrounded by three lips. The species Ascaris lumbricoides is probably the most familiar parasite in humans. At the stage of an embryo they have 6 lips, 3 upper and 3 lower besides them.

Ascaris is a monogenetic parasite, as it's life cycle is completed in a single host that is man. Hence, it's chances of survival is less.

The pseudocoelom is a fluid-filled body cavity lying inside the external body wall of the nematode that bathes the internal organs, including the alimentary system and the reproductive system. The total number of cell bodies present in pseudocoel is five. 

It is a matter of fact that the number of rectal glands in male and female ascaris is 6 and 3 respectively.

Ascaris is an example of pseudo segmentation. True segmentation is found in the animals of phylum Annelida. Body of Ascaris has 4 longitudinal lines, these are called Epider- mal or Ectodermal lines, these lines are formed due to evagination of epidermis of bodywall.

The excretory pore in Ascaris is situated mid-ventrally, a little behind the mouth on the anterior side of the body. There is a single giant H-shaped rennet cell forming an excretory system in Ascaris. It consists of two lateral longitudinal excretory canals.

The egg cytoplasm of Ascaris lumbricoides var. suum is surrounded by three layers: An outer protein coat, a middle chitinous shell, and an inner lipoid lining. Between the cyto- plasm and the lipoid layer in the mature, fertilized egg is a fluid-filled cavity, the perivitelline space.

Morphology of the female reproductive system of Ascaris lumbricoides L. was studied in the region starting with the junction between the oviduct and the uterus (O-U) up to the junction of both uterine branches into the vagina with regard to the process of fertilization and formation of egg-shells. In the O-U junction morphology differed in two following sections: a continuous simple squamous up to simple cuboidal epithelium, and simple cuboidal up to columnar epithelium with broad intercellular spaces leading into the lumen of the tubular reproductive organ filled with sperm. The area in the O-U junction zone was found where the wall of the organ was formed by elongated club-shaped cells attached to the common basal lamina by a narrow pedicle. Intercellular spaces thus formed "crypts" which was covered with dilated parts of cells towards the tubular lumen. Crypts were found to be filled with sperm. This area resembles the structure known as the receptaculum seminis where the stored sperm survive. Epithelial cells of the uterus are of cuboidal up to columnar shape with signs of merocrine secretion. In the distal part of the uterus the secretory active cells probably produce viscous secreta allowing the transfer of the eggs towards the vagina. The cells of the uterus wall are elongated and because of their longer axis, they are orientated longitudinally. In centripetal parts, the cell walls do not have contact with each other and form elongated, deep furrows ("canyons") through which the sperm can run against the flow of uterus content up to the junction of the O-U, where they are stored in the spermatheca-like structure. At any time they are disposal for fertilization.

Larvae develop to infectivity within fertile eggs after 18 days to several weeks, depending on the environmental conditions (optimum: moist, warm, shaded soil). After infective eggs are swallowed, the larvae hatch, invade the intestinal mucosa, and are carried via the portal, then systemic circulation to the lungs.

The epidermis of Ascaris forms four longitudinal thickening, two are lateral lines which contain excretory canal and two thinner dorsal and ventral line. Its excretory system is H-shaped and has two excretory canal that leads to the excretory pore.
Thus, the correct answer is option D.

Fertilization of eggs takes place in the proximal end of the uterus in female Ascaris. A fertilised egg if ingested by humans becomes a larval worm, which enters the walls of the duodenum and then the blood stream.

Ascaris lumbricoides pseudocoelomic fluid is a metabolically active fluid which provides precursor molecules for membrane and cuticular synthesis. It serves as a cavity for circulation, aids in digestion and acts as an internal hydrostatic skeleton that functions in locomotion.
In pseudocoelomic fluid have fatty acid which is caproic acid, valerianic acid, butyric acid are the components of it.
The pseudocoelom is a fluid- filled body cavity lying inside the external body wall of the nematode that bathes the internal organs, including the alimentary system and the reproductive system.

Ascariasis is a disease caused by the parasitic roundworm Ascaris lumbricoides. Symptoms include shortness of breath, fever,  abdominal swelling, abdominal pain, and diarrhoea. Oil of chenopodium is used in the treatment of Ascariasis.  Oil of chenopodium is extracted from the seeds of Chenopodium ambrosioides. Chenopodium is a genus of numerous species of perennial or annual herbaceous flowering plants known as the goosefoots, which occur almost anywhere in the world.
So, the correct answer is 'Adult ascaris'.

Phasmids are chemoreceptors that open one on either side of tail of female Ascaris.

The fine structure of the body-wall in Ascaris lumbricoides was investigated by electron-microscopical techniques. The body-wall is composed of a cuticle, epidermis, and a single layer of muscle cells. The cuticle contains several layers: a superficial membrane, a cortex, the ‘fibrillar layer’, a matrix or homogeneous layer, 3 fibre layers, and a basal lamella. The cortex is divided into a homogeneous, external cortical layer, and a fibrous, internal cortical layer. The ‘fibrillar layer’ is a series of canals which extend from the inner part of the matrix layer to the cortex. The canals have distinct walls but no contents were demonstrated. No fibres or lamellae could, be detected in the matrix layer. The strands of the fibre layers and the basal lamella are formed from fine fibrils, less than 10 m in diameter. There is an inner system of canals that links the epidermis with the basal lamella and the fibre layers. The epidermis has a network of fibres, some of which attach the muscle cells to the cuticle. The muscle cell contains myofilaments of 2 types, an array of large filaments about 30 m. in diameter, each surrounded by a number of smaller filaments about 5 to 7 m in diameter. Glycogen occurs in the epidermis and muscle and is identified as granules; there tends to be a clumping together of granules to form deposits about 100 m in diameter. External to the sarcolemma lies a connective tissue sheath which contains collagen, probably in the form of fibrillar and particulate material.
The cuticles of young adult Ascaris have a basic structure similar to that of the fully grown worms. During the growth of the adult worm the cuticle increases in volume, and this increase involves all the layers of the cuticle. The homogeneous or matrix layer increases in thickness more rapidly than the fibre layers, and both of these layers grow faster than the cortex. Ribonucleic acid is more abundant in the epidermis of young adults than in the fully grown worms and this is correlated with the development of endoplasmic reticulum and ribosomes. It is suggested that the extensive canal system in the cuticle transports materials to all layers of the cuticle.