Brood Capsules Research Articles

SOME PRELIMINARY OBSERVATIONS ON THE DEVELOPMENT OF ECHINOCOCCUS IN VITRO

A variety of media and techniques has been employed in attempts to grow various stages of Echinococcus in vitro. Whole, intact Echinococcus multilocularis cysts and undifferentiated cystic material proliferate readily in chemically defined media, but except for a single occurrence, no scoleces developed within the new vesicles. Scoleces can be induced to develop either toward the tapeworm stage or the vesicular larval stage by altering the medium. In the first case, the scoleces increase in size, the excretory system becomes prominent, and segmentation is advanced; gonads have not developed in any medium yet employed. Scoleces may vesiculate in several ways; ultimately, they become vacuolated, the suckers are absorbed, the hooks shed, and a thin, laminated membrane is laid down. Local internal thickenings probably represent secondary brood capsules or scoleces.

On an unusual brood capsule from a hydatid cyst of a goat in Ceylon.

1. An unusual type of brood capsule is described with the cuticle on the outside and with 70 scolices which are fully developed and projecting outwards. The brood capsule is much larger than the normal brood capsule.2. This type of brood capsule has been described earlier in cultures by Coutelen (1927) and a similar mode of origin has been suggested for this particular brood capsule.

Host-parasite relationships in echinococcosis—IV. Acetylcholinesterase and permeability regulation in the hydatid cyst wall

1. (1) A specific acetylcholinesterase is present in homogenates of hydatid scolices and brood capsules of Echinococcus granulosus. The rate of hydrolysis of acetylcholine is 45 times that of butyrycholine. Enzyme activity is partially inhibited by physostigmine and hexaethyltetraphosphate (HETP). 2. (2) The reducing substance (“glucose”) contents of fluids of 22 hydatid cysts of the bovine lung ranged from 9·2–102·5 mg per cent, of 24 cysts of the bovine liver, from 13·9–101·1 mg per cent. The cyst fluid “glucose” level is higher in cysts from sheep than in cysts from cattle. 3. (3)In hydatid daughter cysts suspended in isotonic Krebs-Ringer's solution for 4 hr, the outward passage of “glucose” occurs very slowly. Passage is accelerated by the addition of small amounts of certain acetylcholinesterase inhibitors to the suspending solution and markedly by the addition of both HETP and either choline or acetylcholine. 4. (4) Accelerated outward passage of “glucose” also occurs when daugther cysts are suspended in hypotonic salt solutions of 0.04 M concentration or less. 5. (5) The weight changes of hydatid daughter cysts suspended in a variety of salt solutions of from 0·039 M to 0·616 M for 2·5 hr are slow, regular and predictable. In solutions similar chemically but more hypotonic, permeability control in the cyst wall appears to break down following a period of water imbibition at the expected rate. Acetylcholine chloride (0·01 M) maintains permeability control to a greater degree than does NaCl at the same molar concentration. 6. (6) Hydatid daughter cysts lose weight more rapidly when suspended in a hypertonic glucose-saline solution for 3 hr than they do in the same glucose-saline which contains small amounts of acetylcholinesterase inhibitors. 7. (7) Extracts of hydatid cyst fluid and hydatid tissues contian one or more unidentified quaternary ammonium compounds.

Renal echinococcus disease.

Renal Hydatid disease is an uncommon occurrence in this country, although in pastoral countries it is not infrequent. Baurys (3) stated that only 35 cases had been reported in the United States at the time he added one case in 1952. The incidence of renal involvement has been variously estimated as from 2 to 9.6 per cent of all cases of echinococcosis. In reviewing renal cystic disease on the urology service of the New York Hospital, Lowsley and Curtis (6) found 2 instances of echinococcosis among 74 cases. Baurys found only 1 case of renal involvement in 240,000 hospital admissions. Etiology Hydatid disease or echinococcosis is a condition in which a cyst or hydatid develops following infestation by the intestinal tapeworm of the dog, Taenia echinococcus. Man is infested chiefly as a result of close contact with dogs. Other intermediate hosts are sheep, swine, and cattle. The parasite in the adult stage measures from 2 to 8 mm. in length and consists of only four segments, the rounded head, presenting a double row of hooklets, and three bisexual segments (2, 7). The eggs are conveyed to man through water and raw vegetables contaminated by cattle or dog feces. When the ovum is ingested by man, its capsule is dissolved in the stomach and there the ovum changes into the intermediate larval form or scolex, encased in the cyst. The larvae then pierce the small bowel wall and pass into the portal or vena caval circulation or into the thoracic duct. The liver is affected in 75 per cent of cases. To reach the systemic circulation, the parasites must pass through the capillary circulation of the liver and, in turn, the capillary bed of the lungs. When they finally reach the kidney, they become vesiculated and development proceeds to the adult cystic stage (9). Pathology The adult cyst wall is layered. The adventitia or outer layer arises from a cellular reaction in the surrounding renal tissues and resembles the fibroblastic reaction about a tuberculous focus (9). This layer is an intimate part of the host kidney and may contain blood vessels. Within the outer layer is the characteristic laminated membrane common to echinococcus cysts of the liver, kidney, and lung (1, 9). This protects the growing scolices on its inner surface and, by its selective osmotic properties, provides nourishment for the germinal elements. These develop first as follicular growths and subsequently as brood capsules containing scolices. The entire cyst secretes fluid into its lumen and slowly enlarges. A diameter of 10 cm. may be reached in ten months (10). It is the consensus that the usual renal hydatid is of many years duration.