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The Balbiani body or mitochondrial cloud is a large distinctive organelle aggregate found in developing oocytes of many species, but its presence in the mouse has been controversial. Using confocal and electron microscopy, we report that a Balbiani body does arise in mouse neonatal germline cysts and oocytes of primordial follicles but disperses as follicles begin to grow. The mouse Balbiani body contains a core of Golgi elements surrounded by mitochondria and associated endoplasmic reticulum. Because of their stage specificity and perinuclear rather than spherical distribution, these clustered Balbiani body mitochondria may have been missed previously. The Balbiani body also contains Trailer hitch, a widely conserved member of a protein complex that associates with endoplasmic reticulum/Golgi-like vesicles and transports specific RNAs during Drosophila oogenesis. Our results provide evidence that mouse oocytes develop using molecular and developmental mechanisms widely conserved throughout the animal kingdom.

A two-dimensional plane stress model of the natural glenoid was developed with finite element analysis to observe the stress distributions under various loading conditions. Different glenoid prosthetic designs were evaluated with the use of the finite element model in an attempt to elucidate key features for an improved design. These included a keel model, a stair-stepped model, and a wedge model. In addition to the evaluation of these designs, different interfaces were introduced to simulate various environments of the prostheses, and different material combinations were studied. Based on the finite element analysis, the following design parameters were found to be important: (1) an all-polyethylene implant appears to provide a more physiologic stress distribution for nonaxial loads if no soft tissue is present; (2) the presence of a soft-tissue layer causes higher stresses; (3) the stair-stepped and wedge models produced a more natural stress distribution compared with the keel design; and (4) screw orientation was not a significant design parameter., (Copyright © 1992 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Mosby, Inc. All rights reserved.)