A review of the anatomy of the reproductive organs of the female African giant rat (<i>Cricetomys gambianus, Waterhouse</i>)

Abstract

This review discusses the state of knowledge of the anatomy of the female African giant rat (Cricetomys gambianus, Waterhouse) reproductive organs with the aim of highlighting various anatomical characterizations and discoveries that have accumulated in the past five decades. Four vaginal mid-smear stages and three intermediate smear stages: late diestrus/early pro-oestrus, late pro-oestrus/early oestrus and late metestrus/early diestrus were reported. The nodular ovaries lie close to irregular coils of the oviducts which lack a distinct border between the ampulla and isthmus. The uterus has two horns and two partially fused cervices, separated by a mid-sagittal septum. Two pairs each, of inguinal and thoracic mammary glands are described. Unique features of the histology include follicles at late proestrus/early diestrus and mid oestrus stages with variably shaped mitochondria, profiles of Golgi complexes and dense concentrations of ribosomes. The theca interna shared similar ultrastructure with the granulosa cells containing in addition, lipid droplets and smooth endoplasmic reticulum. The vaginal basal lamina is highly convoluted during proestrus and oestrus while the epithelium displayed short microvilli at mid proestrus, cornification at late proestrus/early estrus, and desquamation at mid oestrus. Cervical epithelium varied between stratified cuboidal and stratified columnar without glands. Intraepithelial lymphocytes were observed along the vaginal epithelium. The evaluated cyclic patterns of the serum concentrations of FSH, LH, prolactin, estrogen and progesterone showed that the varying histological and ultrastructural features of the ovary at different stages of the oestrous cycle were dependent on these sex hormones. It is therefore recommended that, further investigations should be conducted to formulate colony breeding strategies.