Helminths: Nematodes

Question 1

Enterobius vermicularis

Answer 1

Ovum: 48-80 um long
oval shape with one side flattened
embryo may or may not by embryonated
shell is double layered and colorless

Question 2

Trichuris trichiura

Answer 2

Ova: 50-55um long
football shape
polar plug at each end
embryo is unicellular, undeveloped
shell: smooth, yellow-brown color

Question 3

Ascaris lumbricoides (unfertilized)

Answer 3

85-95um long
oblong shape
embryonated, amorphous mass
shell is usually thin and corticated (bumpy)

Question 4

Ascaris lumbricoides (fertilized)

Answer 4

40-75 um
rounded
undeveloped embryo
shell is thick and corticated (bumpy)

Question 5

Hookworm (ova)

Answer 5

55-75um long
oval
contains 2,4, or 8 cell stages
shell is smooth and colorless
(looks like clumps on a plate)

Question 6

Hookworm (larva)

Answer 6

rhabditiform
270-540um in length
long buccal cavity
small genital primordium

Question 7

Strongyloids stercoralis

Answer 7

rhabditiform larva
220um long
short buccal cavity
prominent genital primordium