Neonatal Porcine Endometrial Development Involves Coordinated Changes in DNA Synthesis, Glycosaminoglycan Distribution, and 3H-Glucosamine Labeling1

Abstract

To determine whether neonatal porcine endometrial development involved alterations in endometrial DNA synthesis, glycosaminoglycan (GAG) distribution, and/or 3H-glucosamine labeling, gilts were assigned randomly at birth (Day 0) to be hysterectomized on either Day 0, 7, 14, 28, 42, or 56. Uteri were processed for histology and Alcian blue-8GX (AB) histochemistry or cultured as explants in the presence of [methyl-3H]thymidine (3H-Thd) or D-[6-3H]glucosamine (3H-GlcN) and processed for subsequent autoradiography. For 3H-Thd-labeled tissues, labeling index (LI; % of nuclei labeled) was determined for two endometrial tissues (epithelium and stroma); two epithelial areas (luminal and glandular); and, for glandular epithelium, in three endometrial zones (zone 1 = shallow, zone 2 = intermediate, zone 3 = deep). For 3H-GlcN-labeled tissues, LI (grains/100 microns2) was determined for two stromal zones (shallow and deep). Endometrial glands were absent on Day 0, present in shallow stroma on Days 7 and 14, and extended to the myometrium in tissues from Day 28 through Day 56. Appearance of endometrial glands was associated with a dramatic increase in glandular epithelial 3H-Thd LI, which was maximal on Days 7 and 14 and declined thereafter. When glands were present in all three endometrial zones (Days 28-56), glandular epithelial 3H-Thd LI was consistently greatest in zone 2. Stromal 3H-Thd LI decreased after Day 0. In tissues obtained after Day 0, a distinct zone of alcianophilia was observed in shallow stroma adjacent to luminal epithelium and surrounding the necks of newly developed endometrial glands. This staining pattern was marked in tissues from Days 7, 14, and 28. Generally, stromal 3H-GlcN LI was greater in shallow than in deep stromal zones; it decreased after Day 0 to minimum values on Days 28 and 42 in both zones, and increased slightly in shallow stroma on Day 56. Data indicate that development of the neonatal porcine endometrium between birth and Day 56 involves coordinated alterations in patterns of DNA synthesis, GAG distribution, and glycoconjugate biosynthesis. The morphogenetic processes characterized here are likely to be regulated locally via changes in tissue microenvironment.

Nursing for 48 Hours from Birth Supports Porcine Uterine Gland Development and Endometrial Cell Compartment-Specific Gene Expression1

“…Consistent with earlier observations [35,37,44,45], differentiation of GE from LE, apparent on PND 2, as well as proliferation and development of nascent uterine glands was marked by intense, tissue site-specific PCNA and ESR1 immunostaining in GE that became more pronounced by PND 14. Patterns of cell proliferation reflected by PCNA immunostaining observed here were similar to those described for nascent uterine GE in the neonatal pig [35,45], sheep [46], and mouse [47,48].…”

Uterotrophic effects of relaxin related to age and estrogen receptor activation in neonatal pigs

“…Transient ERa activation in neonatal gilts, induced by administration of estrogen for 14 days from birth, altered endometrial function and compromised uterine capacity for conceptus support in adults (Tarleton et al 2003). Uterine responses to estrogen in neonatal gilts were exposure period-specific and related directly to endometrial ER architecture characteristic of the period during which exposure occurred (Spencer et al 1993, Tarleton et al 2001. Collectively, data indicate that ER-dependent developmental events characteristic of the period from birth through PND 14 are critical determinants of porcine uterine capacity.…”

Ovarian and Adrenal Contributions to Postnatal Growth and Differentiation of the Rat Uterus

“…Alternatively, EGF and IGF might act as estrogen-dependent mediators of estrogen action in the presence of the ovary and adrenal but independently of estrogen in their absence (i.e., a compensatory mechanism). Spencer et al showed that in the pig, postnatal uterine gland differentiation is accompanied by an increased glandular epithelial cell DNA labeling index and a specific pattern of glycosaminoglycan distribution [2]. Those outcomes, observed during the ovary-independent period of uterine differentiation, led the investigators to conclude that morphogenesis is regulated within the immediate environment of the epithelial cells.…”