Abstract

By the day before birth, the density of nerve fibers in the cervix has increased compared to earlier in pregnancy or in nonpregnant mice. Similar findings are reported in parturient women. To test the hypothesis that connections between the cervix and spinal cord are enhanced by term, the cervix of nonpregnant and time-dated pregnant mice (day 15 or 18 post-breeding) was injected with pseudorabies virus (PRV), a trans-synaptic retrograde neural tract tracer. Mice were euthanized and perfused 5 days later. The spinal cord and cervix were removed and postfixed overnight, immersed in sucrose, and cryostat sections through the thoracic to lumbar regions processed using immunohistochemistry. Cells and fibers that contained PRV were identified by brightfield microscopy. After photomicrographs were digitized, the total area of pixels with specific PRV label was assessed in sensory, autonomic, and motor subdivisions of the lower thoracic to upper lumbar spinal cord. In each subdivision, total area with PRV label was significantly decreased in pregnant mice compared to nonpregnant controls. However, sensory area with PRV label was similar on days 15 and 18 of pregnancy. In both day 15 and day 18 pregnant mice, area with PRV label in the sensory subdivision was >8-fold higher than in both day 15 and day 18 groups autonomic or motor subdivisions. These findings indicate that neural connections between the spinal cord and cervix are not increased with pregnancy or near term. The dramatic reduction in fibers that innervate the cervix from sensory portions of the thoracic to lumbar spinal cord, and to a lesser extent autonomic and motor subdivisions, suggest a paring of synaptic connections in pregnant versus nonpregnant mice. Reduced capability for nocioception at term may result from this decrease in sensory innervation. Rather than support the hypothesis, these findings raise the possibility that hypertrophy of innervation in the cervix by the day before birth may be mediated by local paracrine processes. Fiber pathways that remain at term may be of critical importance for the proposed neuroimmune mechanism that regulates ripening of the cervix in preparation for parturition.

School

Graduate Studies

First Advisor

Michael A. Kirby

Second Advisor

Steven M. Yellon

Third Advisor

P. Ben Nava

Fourth Advisor

Kenneth R. Wright

Degree Name

Master of Science (MS)

Degree Level

M.S.

Year Degree Awarded

2008

Date (Title Page)

6-2008

Language

English

Library of Congress/MESH Subject Headings

Cervical Ripening; Labor, Obstetric -- physiology; Parturition -- physiology; Pregnancy; Analysis of Variance; Neurons -- physiology; Spinal Cord -- physiology; Cervix Uteri -- physiology

Type

Thesis

Page Count

xi; 69

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

Download

Share

COinS