MONOCLONAL-ANTIBODIES SPECIFIC FOR RAT RELAXIN .6. PASSIVE-IMMUNIZATION WITH MONOCLONAL-ANTIBODIES THROUGHOUT THE 2ND-HALF OF PREGNANCY DISRUPTS HISTOLOGICAL-CHANGES ASSOCIATED WITH CERVICAL SOFTENING AT PARTURITION IN RATS
Ab. Lee et al., MONOCLONAL-ANTIBODIES SPECIFIC FOR RAT RELAXIN .6. PASSIVE-IMMUNIZATION WITH MONOCLONAL-ANTIBODIES THROUGHOUT THE 2ND-HALF OF PREGNANCY DISRUPTS HISTOLOGICAL-CHANGES ASSOCIATED WITH CERVICAL SOFTENING AT PARTURITION IN RATS, Endocrinology, 130(4), 1992, pp. 2386-2391
Relaxin, which is secreted by the corpora lutea throughout the second
half of rat pregnancy, promotes the growth and softening of the cervix
. The mechanisms at both the cellular and molecular levels by which re
laxin brings about these effects remain to be determined. The present
study examined the influence of endogenous relaxin on the histological
changes associated with cervical softening. A monoclonal antibody for
rat relaxin, designated MCA1, was injected iv daily on days 12-22 of
gestation. Cervices were removed on day 22, fixed in 10% buffered form
alin, embedded in paraffin, and processed for histological staining. T
issue sections (5-mu-m thick) were stained with Gomori's trichrome sta
in (collagen), Orcein stain (elastin), or periodic acid-Schiff (polysa
ccharide). Qualitative and quantitative analyses identified several hi
stological parameters in MCA1-treated rats that differed markedly from
those in control rats. Cervices obtained from MCA1-treated rats conta
ined collagen fiber bundles with greater compactness; elastin fibers w
ith greater density, length and interdigitation; arteries with smaller
cross-sectional areas; and luminal involutions with smaller areas tha
n controls. The cervices of MCA1-treated rats appeared to contain fewe
r vacuolated epithelial cells, which secrete polysaccharide-rich mater
ial, than did cervices obtained from controls. It seems plausible that
most, if not all, of these relaxin-induced modifications of the histo
logical characteristics of the cervix facilitate birth.