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Morphology and glycoprotein synthesis of uterine glandular epithelium in human basal plate at termAn ultrastructural and autoradiographic study.

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THE ANATOMICAL RECORD 216:146-153 (1986)
Morphology and Glycoprotein Synthesis of Uterine
Glandular Epithelium in Human Basal Plate at
Term: An Ultrastructural and Autoradiographic
Departments of Obstetrics and Gynecology, Washington University School of Medicine,
St. Louis, MO 63110, D. M. N. , E.M.C.);Department of Obstetrics and Gynecology, School of
Medicine, The Ohio State University, Columbus, OH 43210 (J.0.-N.)
This study describes the morphologic features of uterine glandular
epithelium in human basal plate at term and identifies this epithelium as an active
site of glycoprotein synthesis. Wedge biopsies were obtained from the basal plate at
the time of repeat cesarean section from 11 normal pregnant patients at term. Biopsy
specimens were either processed immediately for microscopic examination or incubated in vitro with 25pCi/cc of 3H-galactose or 3H-leucine. Tissues incubated with
tritiated compounds (2-hour pulse f %hour chase in nonradioactive medium) were
either processed for light microscopic autoradiographic analysis or extracted for
determination of trichloroacetic-acid-precipitable
tritiated macromolecules in tissues
and medium, Profiles of cuboidal-columnarglandular epithelium were identified in
the decidual component of the basal plate region adjacent to spiral arterioles and
perpendicular to the inner layers of myometrial muscle. Autoradiographic and
biochemical studies identified the glandular epithelium, as well as large decidual
cells, to be major sites of incorporation of both 3H-galactose and 3H-leucine and to
be prime sources for secretion of tritiated macromolecules that appeared in the
medium during in vitro incubation of basal plate tissue. Ultrastructurally, the
glandular epithelium was noted to rest on a basal lamina, t o have lateral cell
membranes with numerous desmosomes, and to exhibit an apical surface with
microvilli projecting into a luminal space. Cytologic features of the cells included
abundant profiles of rough endoplasmic reticulum, multiple mitochondria with lamellar cristae, a well-developed perinuclear but nonpolarized Golgi apparatus, and
nuclei containing predominantly euchromatin. Lipid droplets and glycogen deposits
were present in some cells. This study indicates that uterine glands persist throughout human gestation in the basal plate and that these glands continue to be active
in glycoprotein synthesis and secretion.
The endometrium of the human uterus undergoes sequential histological changes in response to changes in
ovarian steriod production during the menstrual cycle
(Noyes et al., 1950). These changes involve both the
stroma and the endometrial glandular epithelium and
provide an endometrium primed appropriately to allow
establishment of implantation should a fertilized egg
appear in the endometrial cavity. During implantation,
trophoblast penetrates the uterine epithelium and aggressively invades the stroma and blood vessels in the
area in the process of establishing the site of what will
ultimately represent the basal plate attachment of the
chorionic placenta. Trophoblast has been described to be
involved in phagocytosis of cells composing the glands
during the course of its invasion into the endometrium
(Boyd and Hamilton, 1970). The secretory products of
the glandular epithelum may provide a source of nutrition for the blastocyst prior to the establishment of a
0 1986 ALAN R.LISS. INC.
maternal blood supply during the implantation process.
Other roles for the secretions of the uterine glandular
epithelium during early pregnancy have been suggested
by recent studies (Pijnenborg et al., 1980;Dobashi et al.,
1984; Bulmer et al., 1984) but the presence and role of
uterine glands in later stages of pregnancy are unclear.
During the course of a study of blood vessels in wedge
biopsy specimens of human basal plate of normal and
diabetic patients, we identified the presence of multiple
profiles of glandular epithelium. The current study describes the histological and ultrastructural appearance
Received July 15, 1985; accepted April 16, 1986.
Address reprinted requests to Dr. Michael Nelson, M.D., Ph.D.,
Department of Obstetrics & Gynecology, Washington University
School of Medicine, The Jewish Hospital of St. Louis, 216 S.Kingshighway, St. Louis, MO 63110.
Figure 1.Hemostasis was achieved at the biopsy site by
use of a single 2-0 chromic suture ligature. The specimen was labeled with india ink to identify the area
closest to the myometrium in situ, and then the specimen was cut with a razor blade into 1-2-mm cubes in
anticipation of subsequent fixation or incubation.
- Chorioollanloic
Spiral Artery
- Rodiol
-Arcuate Artery
Arcuate Vein
Fig. 1. Diagrammatic representation of the area where the basal
plate biopsy specimens were obtained at the time of cesarean section.
After creating a cleavage plane, the chorioallantoic placenta was removed and a wedge biopsy of the uterine wall was obtained near the
center of the placenta’s previous attachment site.
Tissue pieces from six patients’ biopsies were distributed to 2cc conical plastic tubes containing 0.5 cc of
medium 199, with or without leucine, with Earle’s salts
equilibrated with an atmosphere of 95% air-5% COZ,
and containing either 25pCVcc of 3H-galactose or 3Hleucine. The alcohol used as a solvent for the stock 3Hgalactose was evaporated with a stream of nitrogen prior
to adding the medium to the 25pCi of 3H-galactose. The
0.01 N HCL was used as a solvent for the stock 3Hleucine was neutralized with an equivalent volume of
0.01 N NaOH prior to the preparation of the 3H-leucine
incubation medium. After 2 hours’ incubation at room
temperature, media containing radioactive tracers were
removed, tissue pieces were rinsed with three changes
of fresh medium 199, and tissues were either frozen or
placed in fixative or incubated an additional 3 hours in
0.5 cc of gassed medium 199 prior to collection of media
and fixation or freezing of tissues. Duplicate incubations
were used for each tritiated compound for each of the
“pulse” and “pulse-chase” incubation.
of uterine glandular epithelium present in the basal
plate attachment site of the chorioallantoic placenta of
normal patients undergoing repeat cesarean section a t
term. Autoradiographic and biochemical analyses of the
incorporation of 3H-leucine and 3H-galactose by basal
plate tissue incubated in vitro were undertaken to determine if the glandular epithelium continued to function
Fixation, Embedding, and Microscopic Examination
in glycoprotein synthesis and secretion. These studies
identify the ‘persistence of uterine glands even at term
Tissue blocks were fixed in 3% glutaraldehyde in 0.1
in the basal plate and show that they continue to be M pH 7.4 cacodylate buffer for 1-2 hours at room temactive in glycoprotein synthesis.
perature, rinsed twice in the same buffer at 4”C, postfixed in 2% osmium tetroxide in 0.1 M pH 7.4 buffer for
1 hour at 4”C, dehydrated in a graded series of cold
ethanols, and embedded in Spurr’s resin. Sections 1Glutaraldehyde, osmium, lead citrate, uranyl acetate, 2pm in thickness were cut with an MT-2 Sorvall Ultraand Spurr’s resin were purchased from Electron Micros- microtome, stained with toluidine blue, and examined
copy Sciences, Fort Washington, PA. Medium 199 with and photographed with an Olympus BHT brightfield
Earle’s salts and medium 199 with Earle’s salts without microscope. Thin sections with silver-gold interference
leucine were purchased from Grand Island Biological colors were stained 7-10 minutes in a saturated solution
Go., Grand Island, NY. Protosol tissue di estant, Aqua- of uranyl acetate in 50% ethanol, rinsed with 50%
sol scintillation cocktail, leucine, L-[4,5,8H(N)] with a ethanol, and stained an additional 7-10 minutes with
specific activity of 59.2 Cilmmole, and galactose, D-[1- lead citrate prior to examination in a Philips 201 elec3H(N)] with a specific activity of 11.5 Cdmmole, were tron microscope.
purchased from New England Nuclear, Boston, MA.
NTB-2 emulsion, D-19 developer, and Ektaflo fixer were
purchased from Eastman Kodak Co., Rochester, NY. All
Four to six sections approximately 1 pm thick were
other chemicals were of reagent grade and were pur- taken from at least three tissue blocks previously exchased from standard suppliers.
posed to a tritiated precursor of glycoprotein synthesis
for one of the designated incubation times. These secBasal Plate Specimens
tions were heat-annealed to clean glass slides and coated
After informed consent was obtained, wedge biopsies with Kodak NTB-2 emulsion as previously described
of the uterine lining at the basal plate were obtained (Nelson et al., 1978).Emulsion was previously tested for
from 11patient volunteers undergoing elective cesarean background and sensitivity prior to its use for coating
section at 38-41 weeks’ gestation. These patients were slides. Coated slides were allowed to dry slowly in a
normotensive throughout pregnancy, were not smokers, high-humidity box prior to storage at 4°C in sealed
delivered infants with birth weights that were average Bakelite slide boxes containing dessicant. After 4-28
for gestational age, and had no known medical diseases days, slides were developed for 2 minutes at 16°C in Dcomplicating their pregnancies. After infant delivery 19 developer, rinsed 1minute in distilled water, fixed 6
and manual removal of the placenta, an elliptical wedge minutes in 25% Ektaflo, and rinsed in two changes of
of tissue approximately 2 cm in diameter and 1 cm in distilled water, 10 minutes each. The gelatin containing
depth was obtained from an area of the basal plate near developed silver grains was then stabilized by exposure
the center of the previous attachment site of the cho- to a 5% aqueous solution of glutaraldehyde which then
rioallantoic placenta as diagrammatically illustrated in allowed staining of tissue sections with warm toluidine
Fig. 2.Photomicrograph of a profile of uterine glandular epithelium
Fig. 3.Photomicrograph of glandular epithelium directly adjacent t o
at the decidual-myometrial interface of the basal plate. The glandular a spiral arteriole which shows the physiologic changes of pregnancy
epithelium consists of a single layer of cuboidal-columnar cells ar- described by Brosens et al. (1967). x 1300.
ranged as a tubular structure perpendicular to the underlying rnyometrial muscle. x 1300.
blue without emulsion damage. Nonspecific blue staining of the gelatin that occurred with this process was
cleared by rinsing slides with a 1%solution of acetic
acid. Developed and stained autoradiograms were examined and photographed by using a n Olympus BHT
brightfield microscope. Under oil immersion a t 1,OOOX
magnification, autoradiograms were used to count grains
overlying grandular epithelial cells and decidual cells
in each of three slides prepared from three different
blocks from each of the six specimens incubated with
either 3H-galactose or 3H-leucine. For uniformity of
grain analysis between pulse and pulse-chase specimens, only cells readily identified as decidual cells and
only glandular epithelial cells cut in cross section perpendicular to their basement membrane were included
in the analysis. Cells tangentially sectioned or whose
origin was unclear by light microscopic examination
were specifically excluded from the grain analysis.
Grains per cell for the glandular epithelial cells and
decidual cells in the pulse specimens were compared
with the labeling of corresponding cells in the chase
specimens by the paired t test.
Tissue and Media Analyses
Frozen tissue samples previously incubated with tritiated galactose or leucine were lyophilized, weighed, and
homogenized in Ten Broeck homogenizers containing 2
cc of ice-cold 20% trichloroacetic acid (TCA). Cold 10%
TCA was then used (5 cc) and TCA-precipitable components were quantitatively transferred from the homogenizer tubes to 25-mm Millipore MF filter discs
(Millipore Corporation, Bedford, MA) placed over the
Fig. 4. Low-magnification photomicrograph of a basal plate biopsy
specimen. Lumina of coiled arteries are indicated by asterisks. A
profile of glandular epithelium lies adjacent to the vessels. Nearby is
an arteriole which has maintained its elastic lamina and circumferential coat of smooth muscle cells (arrow). x 320.
ports of a Millipore sampling manifold (Millipore Corporation, Bedford, MA). After applying negative pressure to the filtration apparatus to adsorb the TCAprecipitable components to the filter discs, two additional 5-cc washes with 10% TCA and one 5-cc wash
with 95% ethanol were placed sequentially over the
filter discs and aspirated by application of negative pressure to the filtration apparatus. The filter discs were
then transferred to glass scintillation vials containing 1
cc Protosol. After overnight Protosol digestions (at 60°C)
of the precipitates from the filter discs, 15-cc of Aquasol
scintillation cocktail was added to each vial and samples
were counted for 10 minutes each in a Nuclear Chicago
scintillation counter. After subtracting background
counts and taking into account the efficiency of counting, results were expressed as c p d m g dry weight tissue.
This value then allowed calculation of the micromoles
of tritiated compound incorporated per milligram dry
weight tissue, thus taking into account the differences
in specific activity of the two tritiated precursors used
in the study.
Frozen medium samples were brought to room temperature, and a 100-p1 aliquot of medium was adsorbed to
a filter disc placed on the Millipore filtration apparatus.
Each disc was then washed twice with cold 20% TCA,
once with cold 95%ethanol, digested with Protosol, and
counted as above. To control for nonspecific adsorption
of 3H-galactose or 3H-leucine with this analysis for TCAprecipitable macromolecules in medium, media not previously incubated with tissue were handled in a manner
similar to that described above. This nonspecific adsorption control had less than 150 cpm per disc for each of
the two tritiated labels, and this amount was subtracted
TABLE 1. Quantitative grain analysis of glandular and
decidual cells
Cell type
Figs. 5-7. Photomicrographs of glandular epithelial cells (Figs. 5 , 6)
and decidual cells (arrow; Fig. 7) in autoradiographs of basal plate
tissue incubated for a 2-hour pulse in medium containing either 3Hleucine (3H-Leu P; Fig. 5 ) or 3H-galactose ?H-Gal P; Figs 6, 7). Qualitatively, autoradiographs prepared by using either tritiated compound
showed labeling of the same cell types as described in the Results
section; 2-week exposure. x 3200.
Figs. 8,9.Photomicrograph of glandular epithelium (Fig. 8 ) and
decidual cells (Fig. 9)from autoradiographs of tissue incubated for a 2hour pulse in 'H-galactosecontaining medium and an additional 3hour chase in nonradioactive medium (3H-Gal C). Silver grains overlying the glandular epithelium in such specimens were present in
fewer numbers than in specimens incubated for the 2-hour pulse only.
In contrast, decidual cells showed no difference in their labeling pattern, with some cells showing no grains or a few grains (Fig. 9, large
arrow) while others had multiple grains (Fig. 9, small arrow); 2-week
exposure. x 3,200.
'Grains per cell is reported as mean k standard deviation with n
indicating number of cells fulfilling the criteria for analysis, as
described in Materials and Methods.
2By paired t test, gland cells from chase specimens had significantly
fewer (P = .001) grains per cell than pulse specimens for each tritiated
3By paired t test, grains per cell for decidual stromal cells from chase
specimens were not significantly different from pulse specimens for
either tritiated compound (P = .35 for 3H-leucine; P = .15 for 3Hgalactose).
8.6 k 4.0
4.3 f 2.7
15.4 f 8.7
5.2 f 3.7
12.9 f 5.7
14.7 f 13.7
13.9 f 12.1
15.1 f 10.3
TABLE 2. Trichloroacetic-acid-DreciDitabletritiated macromolecules
Tissue after pulse3
Tissue after chase3
Medium after chase3
25,316 f 15,918
11,223 f 5,790
8,057 f 5,576
2.98 & 1.87
1.32 & 0.68
0.95 -t 0.66
36,523 t 22,278
24,221 f 10,904
15,927 k 12,332
0.84 t 0.51
0.55 f 0.25
0.36 0.28
'Expressed as counts per minute per milligram dry weight (tissue) or 0.5 cc (medium).
'Expressed as micromoles of tritiated compound in trichloracetic-acid-precipitablemacromolecules per milligram
dry weight (tissue) or 0.5 cc (medium).
3Results expressed as mean k standard deviation.
from the incubation medium cpms prior to calculating
the cpms in the total 0.5-cc sample of medium used for
the chase incubation. The total micromoles of tritiated
compound present as TCA-precipitable macromolecules
in the medium at the end of the incubation was calculated by using the specific activities of 3H-leucine and
Light Microscopic Morphology
Profiles of glandular epithelium were located in the
decidua of the biopsy specimens; often they were observed to be adjacent to myometrial muscle cells (Fig.
2). The epithelium outlined a tubular gland structure
composed of a single layer of cuboidal-to-columnarcells
surrounding a luminal space. Most of the cells had a
basophilic cytoplasm. A single euchromatic nucleus was
centrally located. The profiles of glands were often adjacent to lumina of vessels exhibiting a thin endothelial
lining with stromal cells embedded in a noncellular
meshwork that composed the vessel wall (Fig. 3). Other
adjacent vessels were observed to retain their internal
elastic lamina and circumferential coat of smooth muscle cells (Fig. 4). Lumina of both glands and vessels were
usually free of contents following the fixation and
embedding procedures.
Tritiated Leucine and Galactose Incorporation
for the 2-hour pulse period only, with the appearance of
TCA-precipitable tritiated macromolecules in the medium (Table 2).
Ultrastructural Morphology
The cytologic features of the epithelial cells composing
the glandular profiles are illustrated in Figures 10 and
11. All epithelial cells rested on a basal lamina. Their
luminal surface was composed of multiple microvilli.
Few pinocytotic vesicles were apparent in the apical
cytoplasm. Numerous profiles of rough endoplasmic reticulum without dilated cisternae and mitochondria with
lamellar cristae were distributed throughout the cytoplasm. The ground plasm was less electron dense in
some cells (Fig. 10) than others (Fig. 111,which is possibly related to fixation of ground plasm components. A
well-developed Golgi apparatus was present in the perinuclear region of the cell but no polarity was noted in
its distribution relative to the cells microvillous and
basal surfaces. Glycogen deposits and multivesicular
bodies were present in the cytoplasm of some cells. Lipid
droplets were identified in the basal cytoplasm of numerous cells but secretory granules were not a characteristic feature of the cells. The euchromatic nucleus
was centrally located within the cell.
Close approximation of the apical areas of adjacent
cells was typical of the epithelium with desmosomes
frequently identifiable in this region (Fig. 12) as well as
in other regions of the cells' lateral surface membranes
(Fig. 11). The most apically located surface membranes
of adjacent cells were noted to come into very close
approximation (Fig. 12). However, fusion of these membranes to form the ultrastructrural appearance identifiable as a zonulae occludens was not observed.
Autoradiographic analysis of tissue blocks previously
incubated for 2 hours with either 3H-leucine (Fig. 5) or
3H-galactose (Fig. 6) revealed silver grains associated
glandular epithelial cells (Figs. 5, 6; Table 11, some but
not all decidual cells (Fig. 7, Table l),and a few trophoblast cells. Labeline of the latter two comDonents showed
great variability from cell to cell in a given specimen.
Grains overlying lumina of glands were occasionally
observed (Fig. 6) but no specific labeling of the connective tissue surrounding and enmeshing the decidual cells The basal Plate is the area where the most intimate
interaction of maternal and fetal tissues occurs during
was observed.
By grain analysis, both glandular epithelial cells and gestation. Early in Placental development, troPhoblast
decidual cells showed incorporation of both 3H-gala&,ose invades into the endometrium and subsequently conand 3 ~ - l(Table
~ ~
1). Quantitatively,
~ i ~ ~ analysis of the tributes to alterations Of coiled arteries that Will provide
tissue for incorporated tritiated precursor showed 3H- nutrition to the fetus throughout gestation. Marked alleucine incorporation was less than 3H-galactose incor- terations of the spiral arteriole morphology are required
poration when the different specific activities of the two to accommodate the increased blood flow necessary to
compounds were taken into account (Table 2).
provide adequate perfusion of the chorioallantoic plaAutoradiographic analysis of tissue previously incu- cents- These changes have been the major focus Of a
bated 2 hours in 3H-leucine or 3H-galactosefollowed by number of previous studies of the histology and CfiOlOgy
a 3 how incubation in medium without tritiated corn- of human basal plate, as recently reviewed (Pijnenborg
pounds showed the number of silver grains overlying et ale, 1981)-The C I J I T ~ ~study
describing the Presence
glandular epithelial cells to be much less for both tri- and moQholoD Of glandular epithelium in term basal
tated precursors of glycoprotein synthesis (Fig. 8, Table
1). Labeling of decidual cells after the longer incubation
showed the same variability from cell to cell and the
Same average number of grains Per cell as observed to
Figs. I O , I I . Electron micrographs illustrating typical cytologic feabe present in cells in the tissue incubated for only 2 tures of the glandular epithelial cells as described in the Results
hours. Grains were not concentrated over the lumina of section. Glycogen deposits were absent from many cells fe.g., Fig. 10)
but were present in others (e.g., Fig. 11).The large arrows in Figure 11
the glandular
In addition, there was no de- indicate
desmosomes, which were a characteristic feature ofthe cells'
monstrable labeling Of the extracellular matrix, includ- lateral surface membranes. RER, rough endoplasmic reticulum; W B ,
ing fibrinoid deposits, adjacent to glandular epithelium multivesicular body. Figure 10 x 9700; Figure 11 x 20,200.
or labeled decidual cells (Fig. 9).
Fig. 12. Electron micrograph of the most apical portion of two adja.
Of tissue and medium
from the branes
cent glandular cells' lateral surface membranes. The surface mempulse-chase incubations &owed a drop in the ~adioactivof adjacent cells come into close approximation, as indicated by
ity present in this tissue compared to tissue incubated the arrow, and a desmosome connects the two cells. x 77,800.
plate specimens developed as a separate project during
the course of a similarly focused study of spiral arteriole
morphology, which compared normal and diabetic patients. Wedge biopsy specimens from term basal plate
were frequently noted to contain profiles of epitheliallined spaces, with a well-developed apical microvillous
surface and not encased with a wall of fibrinoid such as
vessels show when they have undergone “physiologic
changes” in pregnancy (Brosens et al., 1967).This observation raised the question as to the fate of uterine glands
at the placental attachment site during gestation and
the realization that little was known about their fate in
human gestation. A systematic study of glandular profile morphology and glycoprotein synthetic activity was
thus undertaken.
Boyd and Hamilton (1970)described the uterine glands
at the site of trophoblast invasion to be ingested or
digested during the early weeks of placental development. From their extensive series of uterine specimens
from various stages of pregnancy, they identified glandular activity to persist through the third month of
gestation but no description of glandular presence beyond this point in gestation was provided. Pijnenborg et
al. (1980) described only isolated fragments of glands
present in specimens obtained at 15-18 weeks’ gestation, and these were predominantly in the marginal
areas of the placental attachment site. They noted that
areas where glandular tissue was lost had trophoblast
cells present throughout the whole thickness of the decidua, but where glands were present, trophoblastic invasion was limited to the compact and spongy layers of
the decidua overlying these glands. An inference from
their study might be that glandular activity contributes
to limiting trophoblast invasion into the basal plate.
Reference to uterine glands in the basal plate in later
gestation is limited. Uterine glands at the placental
attachment site of a single specimen from a 32-week
gestation, described by Harris and Ramsey (19661, were
noted to be compressed. A passing reference to uterine
glands was made by Wells et al. (1984) in noting the
factor VIII and TA1 antigen negativity of residual glands
in their biopsy specimens from term basal plate studied
with immuno fluorescent techniques. The current study
has identified the persistence of glandular profiles in
the decidua of the basal plate at term in the area directly adjacent to the inner layers of myometrial muscle
fibers. The cytology of the cells composing the gland
suggested they continued to have the capacity for active
glycoprotein synthesis, with a well-developed Golgi complex and abundant rough endoplasmic reticulum. Autoradiographic and biochemical analyses of incorportaion
of tritiated precursors for glycoprotein synthesis demonstrated that these cells were active in glycoprotein
synthesis and were a prime source for the tritiated macromolecules that appeared in the medium during the
course of in vitro incubation of basal plate tissue. The
large decidual cells were also active in incorporating
both tritiated compounds, but we found no evidence to
suggest they were actively secreting tritiated macromolecules. However, little is known about the functions of
these large decidual cells, which clearly expressed synthetic activity, and future studies to characterize their
function are contemplated.
The specific functions of the glands and their glycoprotein synthetic products are left to speculation at this
time since the 3H-galactose and ‘H-leucine tracers used
in this study are nonspecific precursors for glycoproteins. However, immunocytochemical studies of uterine
glands from basal plate specimens obtained in early
pregnancy have demonstrated a progestagen-associated
protein (Mazurkiewicz et al., 1981) and Pregnancy-associated Plasma Protein-A (PAPP-A)(Dobashi et al., 1984)
in the cytoplasm of endometrial gland cells. In addition,
Bulmer et al. (1984) have described first-trimester endometrial glands that stain with two monoclonal antibodies that react exclusively with fetal trophoblastic
tissues of the human placenta and extra-embryonic
membranes. They suggested that these antibodies recognize substances similar to pregnancy-associated proteins which could either be produced by glandular tissue
and actively taken up by trophoblast or be produced by
trophoblast and absorbed by glandular epithelium. The
former possibility was dismissed by the authors as unlikely on the assumption that no glands were present in
the placental bed at term, yet trophoblast from term
placenta continued to show reactivity to the monoclonal
antibodies (Johnson et al., 1981; Johnson and Molloy,
1983).The current study’s identification of glands active
in glycoprotein synthesis at term again raises the possibility that they could have a role in secreting the antigen recognized by the two monoclonal antibodies.
The use of 3H-galactoseas one of the tracers for glycoprotein synthesis leaves open the possibility that conversion to glucose through epimerization and incorporation
into glycogen could contribute to a part of the observed
cellular incorporation. However, this route is unlikely
to have contributed significantly to the observed incorporation of 3H-galactose since all cells of the glands
showed incorporation of the compound while glycogen
deposits were not present in all cells. In addition, the
concentration of glucose in the incubation medium was
greater than a million times the concentration of 3Hgalactose; thus making any 3H-glucoseformed through
epimerization occurred at a very low concentration compared to the nonradioactive glucose present.
A final suggested role for the glandular epithelium in
the basal plate is that of providing a source of epithelium to proliferate after delivery of the placenta, allowing reestablishment of a uterine epithelial lining in the
denuded surface at the previous attachment site of the
chorionic placenta. Uterine glandular epithelial proliferation has been described as contributing in a similar
manner to the reestablishment of the uterine lining
following menstruation (Ferenczy, 1976a;b).
In summary, uterine glandular epithelium persists in
the basal plate throughout human gestation and continues to be active in glycoprotein synthesis. Though the
specific secretory products are yet to be determined,
several potential products are suggested from immunocytochemical studies of uterine glands in early pregnancy. Other potential roles for the uterine glands, such
as one in limiting trophoblast invasiveness in pregnancy
or in contributing to the process of reepithelialization of
the uterine cavity after delivery, are interesting possibilities though clearly speculative at this time.
This investigation was supported in part by Department of Health, Education, and Welfare biomedical research support grant t2S07RR05389-22 given to the
Washington University School of Medicine (D.M.N.). We
wish to express our sincere thanks to Dr. Elizabeth M.
Ramsey for her helpful discussions and review of material during the course of this study.
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morphology, human, plato, ultrastructure, synthesis, epithelium, terman, stud, glycoprotein, glandular, autoradiographic, uterine, basal
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