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

To determine whether neonatal porcine endometrial development involved alterations in endometrial DNA synthesis, gly-cosaminoglycan (GAG) distribution, and/or 5H-glucosamine labeling, gilts were assigned randomly at birth (Day 0) to be hys-terectomized 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 (H-Thd) or D-[6-5H]glucosamine (H-GlcN) and processed for subsequent autoradiography. For 3H-Thd-labeled tissues, labeling index (LI; % of nuclei labeled) was determined for two en-dometrial 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 pm2) 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 H-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 5 H-Thd LI was consistently greatest in zone 2. Stromal H-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-GIcN LI was greater in shallow tha