Histology and ultrastructure of the uterus of African giant rat (Cricetomys Gambianus, Waterhouse) during oestrous cycle.

This study describes histology and ultrastructure of uterus in the African giant rat during oestrous cycle. Endometrial histology displayed glandular mucosa consisting of lamina epithelialis and lamina propria mucosae. Its epithelium varied between simple and pseudostratified columnar. The myometrium consisted of inner circular and outer longitudinal smooth muscles with medium sized arteries and veins in-between. The perimetrium contained simple squamous epithelium. Endometrial ultrastructures were variable during oestrous cycle. At mid oestrus, hemidesmosomes anchored undulating basement membrane of the mucosal epithelium. Preponderance spherical mitochondria, lipofuscin granules concentration, flocculent homogenous materials and indented nuclei were displayed. At mid metoestrus, late metoestrus/early dioestrus and mid dioestrus, the base of the mucosal columnar epithelium lain on relatively straight basement membrane and their cytoplasmic ultrastructure displayed variation to mid oestrus. Epithelial apex showed intermediate filament, microvilli and junctional complexes. The uterine glands occurred in variable numbers and sizes during oestrous cycle and shared similar ultrastructure. Mid dioestrus showed cell ultrastructure of uterine glands having apical accumulation of secretory vesicles. Some actively secreting uterine glands were lined by simple ciliated columnar epithelium mingled with pseudostratified epithelium. The findings of the study indicate that giant rat endometrial ultrastructure varies during oestrous cycle and glandular secretion is merocrine.