Microscopy
TAKE EXTREME CARE IN PROCESSING THE SPECIMENS!
INGESTION OF TAENIA SOLIUM EGGS CAN RESULT IN CYSTICERCOSIS!

The eggs of Taenia solium and T. saginata are indistinguishable from each other, as well as from other members of the Taeniidae.  The eggs measure 30-35 micrometers in diameter and are radially-striated.  The internal oncosphere contains six refractile hooks.

A	B

A, B:  Taenia spp. eggs in unstained wet mounts.  Four hooks can clearly be seen in Figure A.

Scoleces of Taenia spp.  The scolex of T. solium contains four large suckers and a rostellum containing two rows of large and small hooks.  There are usually 13 hooks of each size.  The scolex of T. saginata has four large suckers but lacks the rostellum and rostellar hooks.

C	D

C:  Scolex of T. saginata. Note the four large suckers and lack of rostellum and rostellar hooks.
D:  Scolex of T. solium. Note the four large suckers and rostellum containing two rows of hooks.

Proglottids of Taenia spp.  Gravid proglottids are longer than wide and the two species, T. solium and T. saginata, differ in the number of primary lateral uterine branches: T. solium contains 7-13 lateral branches and T. saginata 12-30 lateral branches.

E	F

E, F:  Mature proglottids of T. saginata.  Injection of India ink into the genital pore in Figure F helps with the visualization of the primary lateral uterine branches.  Note the number of branches (>12).

G	H

G, H:  Mature proglottids of T. solium. Injection of India ink into the genital pore in Figure H helps with the visualization of the primary lateral uterine branches.  Note the number of branches (<13).

Cross-sections of proglottids of Taenia spp., stained with hematoxylin and eosin (H&E)

I	J

I:  Cross-section of a proglottid of Taenia sp., stained with hematoxylin and eosin (H&E). Note the thick outer tegument and the loose parenchyma filling the body.  Calcareous corpuscles (red arrows), characteristic of the cestodes, can be seen in the parenchyma.  Eggs (blue arrows) can also be seen.  Images courtesy of the Washington State Public Health Laboratories.
J:  Higher magnification of Figure I showing a close-up of the eggs.  Note the characteristic striations, typical for the taeniids. Not visible in these images are the hooks commonly seen in cestode eggs.  Hooks do not stain with H&E but are refractile and visible with fine focusing of the microscope.

K	L

K:  Close-up of a cross-section of a Taenia sp. proglottid stained with hematoxylin and eosin (H&E), showing numerous calcareous corpuscles (yellow arrows).  Image courtesy of the Michael E. DeBakey V. A. Medical Center in Houston, TX.
L:  Close-up of a cross-section of a Taenia sp. proglottid stained with hematoxylin and eosin (H&E), showing numerous calcareous corpuscles.  Image courtesy of Ameripath.

Adults of Taenia spp.  Adults can reach a length of 2-8 meters, but the scolex is only 1-2 millimeters in diameter.

M	N

M, N:  Taenia saginata adult worms.  The adult in Figure M is approximately 4 meters in length.