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UTERINE DEVELOPMENT IN THE BABOON (Papio cynocephalus): ASPECTS OF ENDOMETRIAL ORGANIZATION IN THE FETUS AND NEONATE.
McLean, Sarah1, Wiley, Anne1, Li, Cun2, Nathanielsz, Peter2, Bartol, Frank1, 1 2
ABSTRACT- The uterus of the adult baboon (Papio cynocephalus) is a simplex organ that supports decidual, hemomonochorial placentation. Little is known about uterine histogenesis in the baboon. However, the importance of defining events associated with this process is reinforced by the fact that exposure of other mammals to endocrine-active agents that disrupt the normal uterine organizational program during critical fetal or neonatal periods can alter adult uterine function and compromise reproductive health. Here, objectives were to describe histochemical relationships characteristic of fetal and neonatal endometrium in the baboon. Uterine tissues were obtained from four fetal (gestational day 135) and four neonatal (week 4, n=3; week 6, n=1) baboons, fixed (4% paraformaldehyde, w/v), and processed together for histological evaluations. Sections from each uterus were stained for proliferating cell nuclear antigen (PCNA; antibody PC10, Zymed Laboratories, Inc., CA), estrogen receptor-
(ER; antibody Ab11,1D5, NeoMarkers, CA) and progesterone receptor (PR; antibody Ab5, hPRa5, NeoMarkers, CA). Fetal and neonatal endometria contained simple columnar luminal epithelium (LE) overlying loosely organized stroma (functionalis), which was penetrated regularly by simple epithelial tubes that extended into deeper stroma (basalis). Compared to fetal tissues, neonatal LE was more regularly corrugated. Occasional coiling of the distal tips of epithelial tubes observed in neonates suggested emergence of glandular epithelium (GE). Staining for PCNA, observed in all cell types, was more intense in the deeper lateral aspects and distal tips of epithelial tubes in fetal and neonatal tissues, and in epithelium lining shallow corrugations of LE in neonates. Intensity of nuclear staining for PR and ER, observed in all tissues, was greater in neonatal uteri. Patterns of ER staining paralleled those observed for PCNA. Results indicate that hyperplastic uterine growth is significant, and that baboon uterine tissues are potential targets for cognate ER and PR ligands in both fetal and neonatal periods. The positive spatial correlation observed for epithelial PCNA and ER staining suggests a functional relationship between ER expression and GE proliferation similar to that reported for ungulate species.
KEY WORDS: uterine development, baboon, fetus, neonate