An acellular human amnionic membrane model for in vitro culture of type ii pneumocytes: The role of the basement membrane in cell morphology and function

To determine whether a preformed basement membrane contributes to the maintenance of morphology and function of type II pneumocytes, we cultured isolated adult rat type II pneumocytes on the basement membrane and stromal surfaces of an acellular human amnionic membrane and on plastic. The presence of lamellar bodies on transmission electron microscopy and epithelial morphology in culture and a characteristic phospholipid profile after incubation with ³H-acetate identified the cells as type II. When type II cells were cultured on a preexisting basement membrane, they formed a well-organized monolayer with polarity, centrally located surface microvilli, and more basally located nuclei. Individual cells maintained a cuboidal morphology for 8–10 days. Intracellularly, there were numerous mitochondria, endoplasmic reticulum (ER), and lamellar bodies. The cells secreted a new basal lamina of their own. When cultured on the stromal side of the amnion, the cells became flattened within 48–60 hours, formed small lamellar bodies, and had scanty surface microvilli; they formed clumps and appeared less ordered. These cells did not secrete a visible basement membrane, and the majority detached from the stromal surface after 7–8 days in culture. In addition, culture on the basement membrane aspect of the amnion prevented the rapid decline in the percentage of ³H-acetate label incorporated in phosphatidylcholine after 72 hours of culture. We conclude that a preformed basement membrane influences the function and morphology of type II pneumocytes, organizes them into a monolayer in culture, and influences deposition of a visible basal lamina. Thus, the acellular human amnion provides an excellent model for the systematic study of basement membrane influence on the biology and pathology of these cells.     

New species of Tephrosia (Fabaceae) from Somalia and Yemen

The new species Tephrosia flava , from limestone areas in north-eastern Somalia, and T. mahrana , from wadis in the deserts of south-eastern Yemen, are described and illustrated.     

Two new species of Crotalaria (Leguminosae) from Somalia

The new, closely related species Crotalaria mudugensis and C. camptosepala , with vicarious distributions in central Somalia, are described and illustrated. The two species are regarded as members of C. sect. Crotalaria along with the related C. verdcourtii and C. deflersu that have previously been placed in sect. Hedriocarpae.     

A new heterostylous species of Streptopetalum (lurneraceae) from Somalia

Streptopetalum arenarium sp. nov., a heterostylous species apparently closely related to the homostylous 5. hildebrandtü in Kenya and north Tanzania, is described from deciduous bushland on sand in central and southern Somalia.     

Four new species of Commicarpus (Nyctaginaceae) from NE tropical Africa

The new species Commicarpus hiranensis from the inland of central Somalia, C. mistus from Somalia, SE Ethiopia, NE Kenya and S Arabia, C. parviflorus from the coastal and subcoastal parts of central Somalia, and C. ramosissimus from NE Somalia are described and illustrated.     

Two new species of Abrus (Leguminosae-Papilionoideae) from Somalia

The new species Abrus baladensis , from fixed sand dunes near Mogadishu in south-central Somalia, and A. gawenensis , from limestone or sand over limestone in central Somalia, are described.     

A new species of Mollugo (Molluginaceae) from Somalia

Mollugo angustifolia sp. nov., from sandy plains of the Bay Region in southern Somalia, is described and illustrated.     

Synopsis of Anthericum and Chlorophytum (Anthericaceae) in the Horn of Africa, including the description of nine new species

Three species of Anthericum and 32 species of Chlorophytum are recognized in Ethiopia and Somalia. Nine new species of Chlorophytum are described, illustrated and mapped: C. applanatum, C. filifolium, C. hiranense, C. littorale, C. nervosum, C. pendulum, C. petraeurn, C. pterocarpum , and C. ramosissimum . Several names are reduced to synonymy and lectotypifications are made in a number of cases. A key to the taxa is presented. One of the species of Anthericum and 16 of the species of Chlorophyturn are confined to the Somalia-Masai Region and endemic or near-endemic in the study area, while one Anthericum and two Chlorophytums are Afromontane endemics or near-endemics in Ethiopia. Most of the other species are more or less widespread mainly Sudano-Zambezian elements.     

A new species of Nesaea (Lythraceae) from Somalia

Nesaea petrensis sp. nov., from seepage areas on granitic outcrops in the Bay Region of southern Somalia, is described and illustrated.