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Query: UMLS:C0277787 (stigma)
 13,352 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Ultrastructural observations on stigmas in rat ovarian follicles have been performed by scanning electron microscopy. Stigmas were classified into two types under a dissecting microscope; extensively bulging vesicles (bleb-type stigmas) and small, flat avascular areas (flat-type stigmas). The bleb-type stigma had lost its surface epithelial cells extensively, and the flattened and densely arranged fibroblasts without fibrous structures were exposed. These fibroblasts had short, serrate, cytoplasmic projections where multivesicular structure-like granules were seen. By contrast, on the flat-type stigma a small region of exposed stroma was covered with fibrous structures. Removal of the fibrous structures by the HCl-collagenase method revealed that the exposed stroma consisted of stellate fibroblasts surrounding a small opening through which a few granulosa cells were about to discharge. When the cumulus mass was protruding, it was surrounded by the fibrous structures. These findings indicate that both the stellate fibroblast formation and the presence of fibrous structures are needed for the release of ova through the stigma.
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PMID:Scanning electron microscopic studies on stigmas in rat ovaries. 712 59

A newly recovered twig with attached leaves and flowers from the Eocene Green River Formation of Utah provides the basis for recognizing a new, extinct genus of Salicaceae sensu lato (s.l.). Pseudosalix handleyi gen. et sp. nov. has alternate lanceolate leaves with pinnate, semicraspedodromous venation and a serrate margin with glandular teeth. The inflorescence is terminal on the twig and is unisexual, composed of flowers organized in a paniculoid cyme, with lateral paraclades of pedicellate flowers. The attached pistillate flowers have four prominent sepals that are valvate in bud, spreading but basally fused at anthesis; the single pistil of each flower is ovoid with three or four longitudinal sutures, indicating development to a capsular fruit. Three or four recurved styles radiate from the apex of the pistil, each with a distal globose stigma. The infructescence, verified by attachment to twigs with the same kind of leaves, bore capsular fruits of three and four valves. Associated but unattached, staminate flowers also have four well-developed, basally connate sepals. They are pedicellate and bear several stamens, each with a short filament and globose anther. The available morphological characters place the fossil species within the Salicaceae s.l. as an immediate sister to the clade containing Populus and Salix. Although the likely outgroup genera (including Itoa, Poliothyrsis, Carrierea, and Idesia) to tribe Saliceae all occur in Asia today and not North America, the occurrence of both Pseudosalix and Populus in the Eocene of Utah raises the possibility of a North American origin for the Saliceae.
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PMID:An extinct genus of Salicaceae based on twigs with attached flowers, fruits, and foliage from the Eocene Green River Formation of Utah and Colorado, USA. 2165 38