TRICHURIS TRICHIURA ( WHIP-WORM )

There are two types of adult worm of Trichuris  trichuura of which one is male and the other is female .

Adult Male Worm –

1)      Shape -  It is whip like in shape . The anterior three fifth portion is very thin and

               hair-like and the posterior two-fifth portion is thick and stout . Thus it   

               resembles a whip-coiled ventrally .

2)      Size -  It measures about 3 to 4 cm in length .

3)      Alimentary tract – The mouth is simple . The hair-like anterior extremity consist of a long , simple , cellular oesophagus which is a minute channel with a single column of large secretory cells . it opens into mid gut . The anus is terminal .

4)      Genitalia –

i)                    Testis – It is long saccular . It runs forward from the posterior part to the anterior part of the body

ii)                  Vas deferens – It ends into cloaca .

iii)                Ejaculatory duct is present .

iv)                Spicule – There is a single spicule which is 2.5mm in length . It is present at the posterior end .

Adult Female Worm –

1)       Shape – The caudal extremity is like a ‘ comma’ or an arc .

2)       Size – It measures about 4 to 5b cm in length .

3)      Alimentary tract – The mouth is simple . The hair-like anterior extremity consists of a long simple , cellular , oesophagus which is a minute channel with a single column of large secretory cells . It open s into mid gut . The anus is terminal .

4)      Genitalia – The worm is oviparous .

i)                    Ovary – It is saccular and tubular . It runs forward from the posterior end of the body .

            ii)           Uterus – Uterus opens into valva through a vagina .

NEMATODES

                       

1)      Shape-  They are elongated , cylindrical or filiform in shape and unsegmented worms without any appendage .

2)      Size -  The size of a bnematode varies from 1 mm to 1 meter in length . The small size nematodes are

              ( I ) Strongyloides stercoralis – There are two forms –

a)       Parasitic form – Parasitic male is seldom seen . Parasitic female measures

                            2.2 mm by 0.075 to 0.3 mm .

b)      Free living form – The female ( rhabditiform ) measures 1 mm by 0.06 mm .

     

         (II)      Trichinella spiralis – The male measures 1.5 mm in diameter . The female   

                                         measures 3 to 4 mm in length and 0.06 mm in diameter .

The largest nematode is Dracunculus medinensis . The female worm which measures about 1 meter in length .

3)      Body surface – The body is covered with a tough resistant cuticle . Longitudinal muscle fibres are present .

4)      The body cavity – The body cavity is unlined pseudocele . Various organs lie in the body cavity . Digestive system an d genital systems float in the body cavity . Excretory and nervous systems are in rudimentary stage . They have no circulatory or respiratory organs .

5)      Sexes -  They are sexually differentiated . The male is generally smaller than  the female . The mouth end of both of the sexes are same but posterior end of the male is coiled ventrally where as in female it is straight .

6)      Alimentary canal -  The alimentary canal is complete . The alimentary canal consists of oral aperture , mouth cavity , oesophagus  , intestine and a subterminal anus . The mouth cavity may contain lip with teeth or cutting plate . The intestine is flat or cylindrical tub e and lined by a single layers of cells .

7)      Nervous system -  This consist of a dorsal , a ventral and four lateral longitudinal trunks with transverse commissures  . The nerves terminate in all organs .

8)      Sensory receptor -  There are some special receptor or sensory organs present in  the nematodes , namely amphids ( olfactory receptor ) , tactile papillae , deirids and phesmids ( caudal chemoretors)  .

9)       Reproductive system -  The nematodes of man are all diecious helminths means the sexes are separate .

(A)    The male genital system – It consist of a long convoluted tube differentiated  

                 into testis , vas deferens , seminal vesicle an d ejaculatory duct . It    

                 opens with the intestine into a common cloaca . Accessory  

                 copulatory organs like one or two unsheathed spicule and   

                 gubernaculums are present . In some cases , copulatory bursa may    

                 be present .

         ( B )  The female genital system – It consist of a single or double convoluted tube .

                                 This tube is differentiated into ovary . Oviduct seminal receptacle ,  

                                  uterus , vagina and valva . The female genital organ ends into   

                                  genital pore which opens on the vental surface of the worm either in

                                  the middle of the body or near the mouth . In case of double tubes ,

                                  the tubes unite form vagina and en ds in the genital pore . The

                                 female nematodes may be divided as –

(a)                 Oviparous          –   The female nematodes lay eggs

(b)                Ovo-viviparous  –   The female nematodes lay eggs which will contain larva

                                  which are immediately hatched out .

(c)                Viviparous          –   The female nematodes give birth larva and they have no       

                                   egg .

ENTEROBIUS VERMICULARIS ( Thread worm or pin worm )

There are two types of adult of Enterobius vermicularis of which one is male and the other is female .

Adult Male Worm –

1. Shape – It is small and white in colour . It is spindle shaped .

2. Size -  It measures about 2 to 4 mm in length and 0.1 to 0.2 in breadth ..

3. The oral end – A pair of cervical alae is present at the anterior extremity . There is

                                      no buccal cavity . The posterior end of the oesophagus is dilated .

4. The posterior end – The posterior third of the body is coiled ventrally and sharply    

                                  truncated .

5. Anus -  Anus is present at the posterior end .

6. Genitalia -         

                      (a)  Testis                                            –  It has a single tubular testis .

         (b) Seminal vesicles                           –  Two in number .

                      (c)  Ejaculatory duct is present .

               (d) Terminal copulatory spicule          – It is about 70μin length without

                                                                               gubernaculums .

(e)    Caudal alae is present at the posterior end .

(f)    Three pairs of postanal sessile papillae and a pair of sessile papillae are present .

Adult Female Worm

1. Shape – It is small and white in colour . It is spindle shaped .

2. Size – It measures about 8 to 12 mm in length and 0.3 to 0.5 mm in breadth .

3. The oral end – A pair of cervical alae is present at the anterior extremity . There is

                                     no buccal cavity . The posterior end of the oesophagus is dilated .

4. The posterior end – The posterior extremity is straight and tapering .

5. Anus – The anus is at the junction of the middle and posterior third of the body .

Genitalia –

i)                    Oviduct are present

ii)                  Uterus is present

iii)                Vagina is present .

ENTAMOEBA HISTOLYTICA

The are different phases in the life cycle of   Entamoeba Histolytica . The morphology of three phases should be - 

1.        Trophozoite  or Vegetative or Growing or Feeding stage .

2.       Pre-cystic stage .

3.       Cystic stage .

Morphology of Trophozite form –

(a)    Shape – For slow glinding movement , shape is not fixed .

(b)   Size – About 18 to 40 µ .

(c)    Cytoplasm –

i)                    Ectoplasm – It is clear and translucent . The ectoplasm throws pseudopodia for locomotion and ingestion of food .

ii)                   Endoplasm – It is granular , R.B.C , W.B.C and tissue debris may be found inside the endoplasm . This portion digests food and got the power of secretion and excretion .

(d)   Nucleus –

i)                    Spherical in shape

ii)                   Size 4 to 6 µ

iii)                 Presence of karyosome in central position and it is surrounded by clear halo .

iv)                 Presence of nuclear membrane which is delicate and lined by a single layer of chromatin granules .

v)                  Presence of linin network in between nuclear membrane and Karyosome .

Morphology of Pre-cystic form –

i)                    It is smaller than trophozite form .

ii)                   Size is 10 to 20 µ .

iii)                 It is rounded or slightly ovoid in shape with a blunt pseudopodium  .

iv)                 The endoplasm does not contain R.B.C or other ingested food particle .

v)                  Nucles

(a)    Spherical in shape

(b)   Size 4 to 6 µ

(c)    Presence of karyosome in central position and it is surrounded by clear halo .

(d)   Presence of nuclear membrane which is delicate and lined by a single layer of chromatin granules .

(e)   Presence of linin network in between nuclear membrane and Karyosome .

Morphology of Cystic form –

(a)    Shape is rounded

(b)   Size is 6 to 15 µ

(c)    It is covered with highly refractile membrane called the cyst wall .

(d)   Nucleus –

i)                    Spherical in shape

ii)                   Size is 4 to 6 µ

iii)                 After maturation of cyst , the single nucleus divided by binary fission and develops into quadrinucleate bodies . The size of the nucleus becomes 2 µ in diameter

(e)   The cytoplasm is clear and hyaline . But in the early stage of development , there are presence of –

i)                    Chromatid or chromidial Bars which can be seen in normal saline preparation as refractile bars and in iron-haematoxylin preparation as black bars . It ius not stained with iodine .

ii)                   Glycogen mass – This stains brown after iodine preparation .

ASCARIS LUMBRICOIDES ( Round-Worm )

There are two types of adult worm of Ascaris lumbricoides of which one is male and the other is female .

Adult Male Worm

1)      Shape – It is rounded and tapers at both ends .

2)      Size – It measures about 15 to 25 cm. in length with a maximum diameter of

                       3 to 4 mm .

3)      Mouth – The mouth open s at the anterior end . There are three finely toothed lips 

                            one dorsal and two ventral .

4)      Tail – The tail end terminates in a coil . The genital pore opens into the cloaca   

           from  .which two curved copulatory spicules protrude . In the cloaca , anus

           opens with  the ejaculatory duct .

5)      The digestive and reproductive organs float inside the body cavity .

Adult Female Worm

1)      Shape – It is rounded and tapers at both ends .

2)      Size – It measures about 26 to 40 cm. in length with a maximum diameter of 5mm .

3)      Mouth – The mouth opens at the anterior end . There are three finely toothed lips ,

                one dorsal and two ventral .

4)      Tail – The tail end is straight and tapering .

5)      The anus opens on the ventral surface as a transverse slit .

6)      The digestive and reproductive organs float inside the body cavity .

7)      The vulva opens mid ventral aspect .