Zhongrong Luo

Abstract

Pineal "synaptic" ribbons are a heterogeneous population of organelles. In addition to "synaptic" ribbons (SR) sensu stricto, which are electron-dense rods, "synaptic" spherules (SS) and intermediate forms (IMF) are present. The SS are electron-dense spherical structures, the diameter of which is two to three times the width of the SR. The IMF appear as irregularly formed structures. The SR, SS and IMF are surrounded by electron-lucent vesicles. Their function and origin are unknown and also a knowledge of their prenatal development is lacking. In order to gain an insight into the development of the "synaptic structures, the pineal glands of pre- and neo-natal, and adult guinea pigs were prepared for electron microscopy. The "synaptic" structures were studied morphologically and quantitatively. The three types of "synaptic" structures reported in adult pineal glands were also present in prenatal pineal glands. Their distribution, grouping and composition patterns are similar to those in adult pineal glands. "Synaptic" structures were first detected in the pinealocytes on day 42 postcoitus (PC). They increased in number with age. At day 63 postcoitus a peak was reached, followed by a steep decline. In the pineal glands of 63-day PC guinea pigs several ribbon synapses were seen between the pinealocyte cell processes or between the pinealocyte cell process and the pinealocyte cell body. These ribbon synapses "were formed by a presynaptic membrane with synaptic ribbons attached, a thickened postsynaptic membrane with dense material, and a slightly widened synaptic space with or without a herringbone-like septum. Since the ribbon synapses have not been found in adult mammalian pinealocytes, their synaptic nature could have been lost during development. By day 69 PC, the "synaptic" structures were increased in numbers again. They showed a drastic increase after birth and reached the highest peak during adulthood. The "synaptic" ribbons first observed were comparable with those in adults. No precursors for the "synaptic" structures were found. The endoplasmic reticulum cisternae may be the origin for the ribbon vesicles because of the close association with the "synaptic" structures. Recognizable sympathetic nerve fibers were found in the pineal glands by day 46 PC.

LLU Discipline

Anatomy

Department

Anatomy

School

Graduate School

First Advisor

Robert L. Schultz

Second Advisor

Paul C. Engen

Third Advisor

John W. Patrickson

Fourth Advisor

Robert A. Chilson

Fifth Advisor

Steven M. Yellon

Degree Name

Doctor of Philosophy (PhD)

Degree Level

Ph.D.

Year Degree Awarded

1988

Date (Title Page)

12-1988

Language

English

Library of Congress/MESH Subject Headings

Pineal Body; Synapses -- physiology

Type

Dissertation

Page Count

vii; 104

Digital Format

PDF

Digital Publisher

Loma Linda University Libraries

Usage Rights

This title appears here courtesy of the author, who has granted Loma Linda University a limited, non-exclusive right to make this publication available to the public. The author retains all other copyrights.

Collection

Loma Linda University Electronic Theses and Dissertations

Collection Website

http://scholarsrepository.llu.edu/etd/

Repository

Loma Linda University. Del E. Webb Memorial Library. University Archives

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