| Abstract: | Reproductive tracts from fetal (d 55 to 150) and neonatal (d 9 to 3 mo) lambs were examined by light microscopy in order to describe ovine uterine histogenesis. Morphologically, d-55 and -60 fetal uteri were bipartite, though characteristic external cornual morphology was not apparent until d 100 to 110. Histologically, lumina of d-55 and -60 fetal uteri were tubular and smooth with no indication of caruncular or glandular areas. In d-90 to -100 fetal uteri, luminal clefts were visible along the mucosal surface and a band of eosinophilic, elongated, smooth muscle-like cells was distinguishable. By d 100 to 110, nodular and internodular areas were clearly defined as luminal clefts deepened. Expansion of deep internodular areas, parallel to the luminal nodular surface, progressed in fetal uteri from d 118 to 150. Slight invaginations along deep internodular areas were visible in d-135 fetal uteri and were regular features of d-150 fetal uteri. In contrast, shallow, slightly coiled simple tubular glands were visible in the endometrium of internodular (intercaruncular) areas in a d-9 neonatal uterus. Older neonatal uteri (d 26 to 3 mo) contained coiled tubular glands which extended to the myometrium. Data indicate a systematic pattern of ovine uterine histogenesis involving dynamic morphogenetic alterations, especially between d 80 to 130 of fetal life. The observation that uterine glands were absent in fetal uteri but present in neonatal uteri suggests that glandular induction must occur during the periparturiet/neonatal period. |
