TheAnatomicalRecord ORIGINALLY FOUNDED BY THE WISTAR INSTITUTE Aaron J. Ladman, Editor Department of Anatomy Mail Stop 408 Hahnemann University Broad & Vine Philadelphia, Penns)Tlvania 19102-1192 EDITORIAL BOARD Peter S. Amenta Hobert Wood Johnson Medical School John V. Basmajian Chedoke Rehabilitation Center McMaster University Dale E. Bockman Medicdl College of Georgia Robert M. B r e n n e r Oregon Regional Primate Research Center Robert S. Bressler New York College of Podiatric Medicine Margaret R. Byers University of Washington Edward C. Carlson University of North Dakota John Clancy, Jr. Loyola University School of Medicine Ben R. Clower University of Mississippi Jackson Richard E. CoggeshaU The University of Texas Medical Branch at Galveston Gerald R. C u n h a University of California San Francisco William G. Dail, Jr. The llniversity of New Mexico Dennis M. D e Pace Hahnemann University Richard D. Dey West Virginia University Donald J. Donaldson University of Tennessee Memphis M a r t i n Dym Georgetown University Stanley 1. Erlandsen University of Minnesota Medical School Richard A. Ellis Brown University John F. Fallon Barry F. King University of California Davis University of Wisconsin Madison Charles J. Flickinger University of Virginia Daniel S. Friend University of California San Francisco Geraldine F. Gauthier The University of Massachusetts Michael D. Gershon Columbia University Jefkey T. Laitman William J. Gonyea The University of Texas Health Science Center at Dallas Jack L. Haar Medical College of Virginia James 1. Matthews D u a n e E. Haines University of Mississippi Jackson Damon C. Herbert The University of Texas at San Antonio Louis H e r m o McGill University John C. Herr University of Virginia Sam G. McClugage Robert Hikida Ohio University David E. Hinton University of California Davis Webster S.S. Jee University of Utah Gordon 1. Kaye Albany Medical College Robert 0. Kelley The University of New Mexico Eric R. lacy Medical University of South Carolina Mount Sinai School of Medicine New York Thomas A. Marino Temple University School of Medicine Roger R. Markwald Medical College of Wisconsin Milwaukee George F. Martin Ohio State University Baylor College of Dentistry Dallas Joseph T. McCabe Uniformed Services University Bethesda Louisiana State llniversity New Orleans R. Peter Meyer Hahnemann University Bryce 1. Munger University of Tasmania Charles C.C. O M o r c h o e University of Illinois College of Medicine UrbanaChampaign David P. P e n n e y University of Rochester Elio Raviola Harvard Medical School Thomas S. Reese National Institutes of Health L v n n 1. Romrell Ukiveisity of Florida Gainesville Manuscripts and illustrations intended for publication in The Anatomical Record should be sent to Dr. Aaron J. Ladman, Department of Anatomy, Mail Stop 408, Hahnemann University, Broad & Vine, Philadelphid, Pennsylvania 19102-1192. Please read notice to contributors on inside back cover page for preparation instructions. Officers of the American Association of Anatomists for 1992-93: Alan Peters, president; William P. Jollie, president emeritus; Donald A. Fischman, president-elect; Charles E. Slonecker, first vicepresident; Gary C. Schoenwolf, second vice-president; Marilyn Zimny, program secretary; Robert D. Yates, secretary-treasurer. 0 1992 Wiley-Liss, Inc. All rights reserved. No part of this publication may be reproduced in any form or by any means, except as permitted under section 107 or 108 of the 1976 United States Copyright Act, without either the prior written permission of the publisher, or authorization through the Copyright Clearance Center, 27 Congress Street, Salem, MA 01970, (508) 744-3350, fax (508) 745-9379. Requests to the publisher for permission should be addressed to the Permissions Department, John Wiley & Sons, Inc. THE ANATOMICAL RECORD (ISSN 0003-276>0, an official publication of the American Association of Anatomists, is published monthly by Wiley-Liss, Inc., a division of John Wiley & Sons, Inc., 605 Third Avenue, New York, NY 10158-0012. Send subscription inquiries to: John Wiley &Sons, Inc.,Subscription Department, 9th floor, 605 Third Avenue, New York, NY 10158; Phone: (212) 850-6543. For 1992, Jack Rosenbluth New York University Ray Runyan University of Iowa Linda Wand The University of New Mexico Gary Schoenwolf University of Utah Arlen R. Severson University of Minnesota Duluth Peter J. Sheridan The University of Texas at San Antonio Akhouri A. Sinha Veterans Affairs Research Service University of Minnesota Mike1 H. Snow University of Southern California Sergei P. Sorokin Boston University A.K. Szakal Medical College of Virginia Bernard Tandler Case Western Reserve University Robert J. Tomanek University of Iowa Jerry S. Trier Brigham and Women's Hospital Boston John A. Trotter The University of New Mexico A. Wayne Vogl University of British Columbia Hershey Warshawsky McGill University Robert E. Waterman The University of New Mexico Frederick Wezeman Loyola University of Chicago Chicago Lawrence C. Zoller Boston University Volumes 232-234, twelve issues, $1,280.00 in US; $1,430.00 o u t side US. For 1993, Volumes 235-237, twelve issues plus Supplement 1, $1590.00 in US; $1720.00 in Canada and Mexico; $1768.75outside North America. All subscriptions outside iJS will be sent by air. Payments must be made in US dollars drawn on a [IS bank. Change of address: Please forward to the Subscriptions address listed above six weeks prior to move; enclose present mailing label with change of address. Claims for missing issues: Claims for undelivered copies will be accepted only after the following issue has been received. Please enclose a copy of the mailing label or cite your subscriber reference number in order t o expedite handling. Missing copies will be supplied when losses have been sustained in transit and where reserve stock permits. Send claims to John Wiley & Sons, Inc., Customer Service,605 Third Avenue, New York, NY 10158. If claims are not resolved satisfactorily, please write to Susan Malawski, Director, Subscription Fulfillment and Distribution,John Wiley & Sons, Inc., 605 Third Avenue, New York, NY 10158. Cancellations: Subscription cancellations will not be accepted after the first issue has been mailed. Volumes published prior to 1980 are available from Swets and Zeitlinger B.W P.O. Box 810, 2160 SZ Lisse, The Netherlands. Second class postage paid at N.Y., N.Y., and at additional mailing offices. Printed in U.S.A. Copyright 0 1992 Wiley-Liss, Inc. POSTMASTER Send change of address to The Anatomical Record, Susan Dorato, Subscription Fulfillment and Distribution, John Wiley & Sons, Inc., 605 Third Avenue, New York, NY 10158. Indexed by: BIOSIS Data Base, Chemical Abstracts, Current ContenWLife Sciences, Science Citation Index, Scisearch, Excerpta Medica, Index Medicus, Reference Update, Biological & Agricultural Index, and Institute of Scientific Information-Soviet Union. This journal is printed on acid-free paper.