Staging of the estrous cycle and induction of estrus in experimental rodents: an update

Abstract

Background: Determination of the phases of the estrous cycle and induction of estrus (heat) in experimental animals remains useful, especially in reproductive function research. Main body of the abstract: This review provides a detailed description and discusses extensively the variations observed in different phases of the estrous cycle in laboratory animals using rats and mice as examples. It also illustrates how these phases can be determined and how to induce estrus 'heat' when required. The phases of the estrous cycle can be determined using various methods such as visual assessment, vaginal smear/cytology, histology of female reproductive organs (vagina, uterus and ovaries), vaginal wall impedance assessment and determination of urine biochemical parameters. Female animals can be artificially brought to estrus phase 'heat' to make them receptive to male counterparts. Conclusion: Determination of the length and phases of the estrous cycle and induction of estrus are useful in teaching and research and evaluating the effects of drugs/chemicals on the reproductive functions.

Early Adolescence Prefrontal Cortex Alterations in Female Rats Lacking Dopamine Transporter

“…Although most psychiatric disorders cited across our study present higher prevalence in women, we acknowledge that our study focused only on female rats, and further studies are needed to expand our results also in male rats. Additionally, we studied female rats at PND35, the time point during development when hormones have been described to be almost ready to start the first proestrus cycle [ 80 ]. We acknowledge the need for future studies considering the role of hormones modulating glutamatergic synaptic response.…”

HAART and anti‐Koch’s impair sexual competence, sperm quality and offspring quality when used singly and in combination in male Wistar rats

“…Only sexually receptive female rats were used. Sexual receptivity was characterised by gapped vagina which was pinkish and moist with prominent striations on visual assessment and the presence of about 75% cornified epithelial cells and 25% nucleated epithelial cells on vagina smear (Ajayi & Akhigbe, 2020d). In addition, receptive female rats showed characteristic lordosis and male acceptance (Hamid & Zakaria, 2013).…”

Spatiotemporal transcriptional dynamics of the cycling mouse oviduct

“…The absence of significant remodeling of MCCs across the estrous cycle in the mouse oviduct presents a marked contrast to other mammals (Brenner, 1969; Shirley and Reeder, 1996; Verhage et al, 1973). We hypothesize that this discrepancy may relate to the very short (4 to 5 day) mouse estrous cycle (Ajayi and Akhigbe, 2020) and time required to eliminate and re-establish ciliated cells.…”

“…Mice were housed in individually ventilated cages in a pathogen-free facility with continuous food and water, with a controlled light cycle (light from 7am-7pm). 7-9-week-old females were estrous cycle staged using standard vaginal cytology (Ajayi and Akhigbe, 2020). Mice were humanely euthanized with extended CO 2 exposure followed by cervical dislocation, and female reproductive tracts were dissected.…”