Search

Paleal notochaetae belonging to a number of Chrysopetalum species (Chrysopetalidae) were examined by scanning and transmission electron microscopy. Paleae are composed of broad medullary channels stacked with a regular series of horizontal fibrous diaphragms. The medullary part of the palea is surrounded by irregular rows of narrow tubular channels within the chaetal cortex. The origin and function of camerate chaetae is discussed.

Erwinia chrysanthemi (biovars 5 and 6) was isolated from unusual symptoms on witloof chicory, both in the field and in hydroponic culture, in Brittany in 1989 and 1990. Symptoms included a greyish-brown soft rot on the lower part of the root and the destruction of the cortical tissues. The cribrovascular and the medullary part of the bottom of the root sometimes became slimy. A few cases of vascular transmission were observed, which resulted in a red coloration of the infected vessels and a soft rot of the leaves (...)

A clinical and pathologic analysis of 30 lipid cell tumors of the ovary shows that both adrenocortical-like and hilus-like cells are present in most instances and that attempts to separate them objectively into adrenal-like tumors, hilus cell tumors or stromal luteomas is often impossible. Inasmuch as there is no histogenetic basis for employing this terminology, such a separation is considered artificial and of no value in predicting either functional manifestations or clinical behavior. Therefore, lipid cell tumors are regarded as a specific entity and not a collection of different lesions. Lipid cell tumors are most often virilizing (77% of patients) and may be associated with Cushing's syndrome (10% of patients) or with evidence of estrogenic activity (23% of patients). Although these tumors usually are considered benign, six patients in this series died of recurrent or metastatic tumor. The clinically malignant lipid cell tumors tended to be larger than the benign ones, had involved contiguous pelvic structures at the time of operation in half of the cases, and occasionally exhibited sufficient cellular pleomorphism and mitotic activity to permit objective interpretation as malignant. On the basis of the authors' findings and the evidence available in the literature, the most likely origin of lipid cell tumors is from the specialized ovarian stromal cells within the medullary part of the ovaries.