Society for Reproductive Biology Founders' Lecture 2003. The making of an embryo: short-term goals and long-term implications

During early development, the eutherian mammalian embryo forms a blastocyst comprising an outer trophectoderm epithelium and enclosed inner cell mass (ICM). The short-term goal of blastocyst morphogenesis, including epithelial differentiation and segregation of the ICM, is mainly regulated autonomously and comprises a combination of temporally controlled gene expression, cell polarisation, differentiative cell divisions and cell-cell interactions. This aspect of blastocyst biogenesis is reviewed, focusing, in particular, on the maturation and role of cell adhesion systems. Early embryos are also sensitive to their environment, which can affect their developmental potential in diverse ways and may lead to long-term consequences relating to fetal or postnatal growth and physiology. Some current concepts of embryo-environment interactions, which may impact on future health, are also reviewed.     

Toxocariasis: under-estimated disease. Report of 9 cases

Toxocariasis or visceral larva migrans is a parasitosis due to the migration in the human organism of animal ascarid larvae. Its importance is under-estimated and the reported tunisian cases are rare. We report nine cases of toxocariasis, noted between January of 2000 to March of 2002, in the laboratory of parasitology-mycology in La Rabta Hospital. They were six children and three adults. The clinical forms are varied: ophthalmologic form (5 cases), general syndrome (1 case), oedema (1 case) and hypereosinophilia (2 cases), and confirmed serologically by the presence of anti Toxocara canis antibody using ELISA test. Visceral larva migrans should be kept in mind to avoid severe forms such as ophthalmologic forms.     

Murine thrombosis models

Due to exciting advances in molecular biology, the laboratory mouse has become an important and frequently used model for studying thrombosis. This article reviews several experimental approaches that have been used to study arterial, venous, and microvascular thrombosis in mice. The advantages and limitations of different models are examined. Related topics of mouse anesthesia, phlebotomy, and in vitro hemostasis testing are also reviewed.     

Two cases of orbital lymphangioma associated with vascular abnormalities of the retina and iris

PURPOSE: To report 2 patients with combined intraocular and orbital vascular abnormalities. DESIGN: Two interventional case reports. MAIN OUTCOME MEASURES: Clinical and pathologic findings. INTERVENTION/TESTING: Orbitotomy, fluorescein angiography, magnetic resonance imaging, and radiation therapy. RESULTS: Two patients presented with vision loss, intermittent proptosis, and cosmetic deformity. These patients had orbital lymphangioma, ipsilateral retinal and iris vascular malformations, and smaller corneal diameter on the affected side. CONCLUSIONS: The coexistence of these diverse vascular anomalies supports the established hypothesis of pluripotential orbital vascular anlagen. Disruptive influences of various types during embryogenesis or development may produce a variety of congenital orbital and intraocular vascular malformations.     

Importance of nonpharmacological factors in nicotine self-administration

There is mounting evidence that nonpharmacological factors critically modulate the effects of several drugs of abuse both in humans and experimental animals. This paper reviews research from this laboratory on one factor that influences the degree to which nicotine is self-administered: environmental stimuli that form the context within which nicotine is taken. The results suggest that the direct, pharmacological actions of nicotine are necessary but not sufficient to explain either the high rates of self-administration exhibited by laboratory animals or cigarette smoking by humans, and that future investigations on the neurophysiological effects of nicotine that underlie smoking behavior must take into account the environmental context within which the behavior occurs.     

Sampling error in the standard evaluation of endoscopic colonic biopsies

It is assumed that the diagnostic information in small gastrointestinal mucosal biopsies is obtained regardless of which side of the biopsy is sectioned. Based on this assumption, mucosal biopsies of the colon are embedded randomly with respect to the side of the biopsy that faces the microtome blade. Our hypothesis is that reorienting ("flipping") the biopsy specimen 180 degrees and sectioning the opposite side might provide new diagnostic information in cases with no specific histopathologic diagnosis. Sixty-one consecutive cases with a clinical impression of a polyp and no histologic abnormality on three hematoxylin and eosin-stained slides (6-15 levels) were selected. Formalin-fixed, paraffin-embedded tissue was reoriented, and three additional hematoxylin and eosin-stained slides (6-15 levels) were evaluated. The side of the specimen initially sectioned was arbitrarily designated "A," and the side of the specimen sectioned after reembedding was designated "B." The slides were sequentially numbered 1-3, and the first slide on which the new diagnosis was evident was recorded. New diagnoses were made for 19 of 61 (31.1%) specimens from a total of 51 patients and included tubular adenomas (12 of 61; 19.7%) and hyperplastic polyps (7 of 61; 11.5%). In 17 of 19 specimens (89.5%), the new diagnosis was evident on the first slide. Reembedding endoscopic colonic biopsies facilitates rendering a definitive diagnosis in cases of discordance between the clinical impression and the histologic impression. Routine examination of at least two sides of randomly oriented biopsy material could provide additional diagnostic, and sometimes critical, information.