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Article
Ultrastructural Analysis of Folliculogenesis in the Ovary of the Yellow Spotted Stingray, Urolophus jamaicensis
Annals of Anatomy - Anatomischer Anzeiger
  • William C. Hamlett, Indiana University School of Medicine
  • M. Jezior, Uniformed Services University of the Health Services
  • Richard E. Spieler, Nova Southeastern University
Document Type
Article
Publication Date
3-1-1999
Keywords
  • Ovary,
  • Follicle,
  • Ultrastructure,
  • Elasmo-branch,
  • Transosome
Abstract

The ovary of the yellow spotted ray, Urolophus jamaicensis, is embedded in the epigonal gland, a lymphomyeloid organ. The covering of the ovary is composed of a germinal epithelium that is cuboidal and dome-shaped with microvilli. Adjacent cells have elaborate intercellular folds that create dilated intercellular spaces. In previtellogenic follicles, the follicle cells are simple cuboidal and contain modest amounts of synthetic or transport organelles. As vitellogenesis proceeds, the epithelium becomes multilaminar. Follicle cells are columnar as yolk precursors are transported from the maternal circulation, through the follicle cell cytoplasm, to the oocyte. Large, round cells occur in the follicle wall that contain lipid-like substances. These cells decrease in size and number as folliculogenesis proceeds and eventually disappear prior to ovulation. Columnar follicular cells and the oocyte have cellular extensions that impinge upon the zona pellucida. Transosomes are follicle cell extensions that indent the oocyte membrane. Tips of transosomes become enclosed by a layer of oocyte plasmalemma. The tips of transosomes pinch off and become resident in the ooplasm. Dense staining material occurs on the inner surface of the transosome membrane derived from the follicle cell. In other animals, this material has been described as ribosome-like. This study is the first to document the presence of transosomes in a group other than Aves or reptiles. Follicle cells are supported by an extremely thick basal lamina. Subjacent to the lamina is the vascularized theca with fibroblasts embedded in a collage-nous network. There is no differentiation into definitive theca interna and externa. In vitellogenic eggs, extensive inward foldings of the follicular epithelium occur thereby generating more surface area for the transport of yolk precursors to the oocyte. Atretic follicles are common.

DOI
10.1016/S0940-9602(99)80003-X
Comments

©1999 Urban & Fischer Verlag. Published by Elsevier GmbH All rights reserved.

Citation Information
William C. Hamlett, M. Jezior and Richard E. Spieler. "Ultrastructural Analysis of Folliculogenesis in the Ovary of the Yellow Spotted Stingray, Urolophus jamaicensis" Annals of Anatomy - Anatomischer Anzeiger Vol. 181 Iss. 2 (1999) p. 159 - 172 ISSN: 0940-9602
Available at: http://works.bepress.com/richard-spieler/3/