Morphological adaptations for histotrophic nutrition in the placenta of West African Dwarf goats.

Gravid uteri harvested from 11 pregnant West African Dwarf goats were used to study morphological adaptations for secretion and absorption of histotroph in interplacentomal areas of the goat placenta. The results showed numerous glandular acini in the richly vascularized sub-epithelial connective tissue of the endometrium. Secretory cells of the glandular acini exhibited cytoplasmic organelles for synthesis and packaging of secretory products, as well as many membrane-bound secretory vesicles. At the foeto-maternal interface, microvillar interdigitations occurred between uterine epithelial cells and foetal trophoblasts. In addition, areolae were observed near the openings of uterine glands onto the endometrial surface. Trophoblast papillae, which are evaginations of the foetal chorioallantoic membrane, extended into the areolar cavity and lumina of uterine gland openings. The areolae are specialized sites for storage and absorption of uterine gland secretions, while trophoblast papillae may correspond to areas for substantial absorption of uterine gland secretions by foetal trophoblasts. Areolae and trophoblast papillae persisted up to day 90 of gestation in the West African Dwarf goat. This suggests that uterine gland secretions are required by the conceptus even after implantation and establishment of haemotrophic nutrition in the goat. Thus, this study has provided morphological evidence for substantial production and transfer of uterine gland secretions from the dam to the foetus in interplacentomal areas of the placenta of West African Dwarf goats.