Trichomonad total extracts (TTE), or vesicular (P30) and soluble (530) subcellular fractions from 3 pathogenic Trichomonas vaginalis strains (GT-3. GT-13. and GT-15), lysed both human and Sprague-Dawley rat erythrocytes in a time- and dose-dependent manner. The entire hemolytic activity of TTE was located in P30, showing 2 peaks of maximum activity, one at pH 6.0 and another at pH 8.0. in the presence of 1 mM Ca2+. Hemolytic activity on rat erythrocytes was greater at pH 6.0 16.71 +/- 0.33 hemolytic units IHU]/mg/hr to 11.60 +/- 0.24 HU/mg/hr) than at pH 8.0 (3.81 +/- 0.30 HU/mg/hr to 5.75 +/- 0.65 HU/mg/hr). and it was greater than that on human red blood cells at pH 6.0 (2.67 +/- 0.19 HU/mg/hr to 4.08 +/- 0.15 HU/mg/hr) or pH 8.0 (2.24 +/- 0.0 9 HU/mg/hr to 2.81 +/- 0.06 HU/mg/hr). The alkaline and acidic hemolytic activity diminished (60-93% at pH 6.0 and 78-93% at pH 8.0) by the effect of 80 microM Rosenthal's inhibitor, which also inhibited 27-45% and 29-54% trichomonad alkaline and acidic phospholipase A activities, respectively. Vesicles, vacuoles, and hydrogenosomes were rich in P30. Trichomonas vaginalis has a hemolytic PLA, which could be involved in its cytopathogenic mechanism.

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Ethyl methanesulphonate (EMS) is a mutagenic alkylating agent that induces marked elevations of sperm abnormalities in mice. In this paper, we report the ultrastructural findings on the morphology of the seminiferous epithelium of mice resulting from EMS administration. Eight- to twelve-weeks-old male mice were injected intraperitoneally with EMS at 200 mg kg(-1) body weight daily for five consecutive days. Analysis of smears of epididymis and semi-thin sections of testes revealed that the more suitable specimens for the ultrastructural analysis were tissues of mice killed at the third week, following EMS administration. At this time, the spermatid was the damaged cell type. Abnormalities were mainly observed in the morphology of the nucleus, the acrosome, chromatin distribution and in the arrangement of the cytoplasmic microtubules, and binucleated spermatids were also observed. EMS has the capacity to penetrate the blood-testis barrier, and thus it can damage post-meiotic spermatogenic cells. However, morphological abnormalities could be the consequence of damage exerted on the differentiated spermatogonia stage, the most sensitive spermatogenic cell to the action of chemical agents or drugs. Our findings contribute to elucidate the action mechanism of the damage exerted by EMS administration on the germinal male cells.

The cyst of Entamoeba histolytica is the infective phase of this parasite, but much of its differentiation process remains unknown since it is not possible its in vitro encystation. However, differentiation of E. invadens, an ameba that parasites reptiles is used as an experimental model for amebiasis research, specially in differentiation aspects, since E. invadens can be induced to in vitro encystation.The nuclear division during encystation of E. invadens has been described by some authors, but this work, has described this process through light microscopy. In the present work we report the morphologic nuclear change and the chromatin organization observed by electron microscopy.Trophozoites of E. invadens IP-1 were grown in TP-S-1 medium, and encysted in Rengpien and Bailey medium (AEM). During encystation several samples were analysed for different times. The cysts of trophozoites were washed with phosphate buffer saline, postfixed in 1% osmium tetroxide in 0.2 M phosphate buffer pH 7.2 dehydrated in ethyl alcohol and embedded in epoxi resin.

Introduction:- The metacestode (larval stage) of Taenia multiceps, it is characterized by its big bladder fluid filled and multiple scoleces. Affect very frequently herbivorous mammals like sheeps, hares and rabbits (1); and occasionally humans (2), causing disorders very similars to that caused by Cysticercus cellulosae (3), the larval stage of Taenia solium. The adult parasite, Taenia multiceps, it is found in the intestine of domestic and wild carnivorous like dogs, wolves and coyotes.In this paper we describe the morphology at the optical and electron microscope level of coenuri collected from hares.Material and Methods.- Coenuri collected from hares, were dissected from muscle tissues and fixed in glutaraldehyde 2.5% in 0.1M phosphate buffer pH 7.4, postfixed in 1% osmium tetroxide in the same buffer. Inclusion in medcast resin (Pelco). Sections were stained with uranyl acetate and lead citrate, and observed in a Zeiss EM 109 electron microscope.