Work

Spatial differences in the ovine cervical microenvironment at the follicular and luteal phases of the oestrous cycle; Implications for sperm transport

Year: 2026

Type: article

Abstract: The complex anatomy of the ovine cervix presents a significant barrier to transcervical artificial insemination, necessitating sperm deposition at the external cervical osmium. This study aimed to evaluate the cervical microarchitecture to elucidate the mechanisms orchestrating sperm transport across the cervix. Cervices from crossbred ewes (n = 13) were harvested during the follicular (n = 6) and luteal (n = 7) phase, sectioned into 10 transverse segments from external to internal osmium (1 = External cervical osmium; 10 = Internal cervical osmium), and analysed for epithelial morphology and microgroove architecture. Columnar epithelium predominated throughout the cervix, with a squamocolumnar junction localised at the external osmium. Columnar cell height was significantly greater during the follicular phase (33.3 ± 1.31 μm) than the luteal phase (26.7 ± 1.21 μm; p < 0.001). Cervical microgroove surface area increased during the follicular phase (p < 0.05). Microgroove surface area, depth, and tortuosity (deviation from a straight line) increased progressively toward the internal Os and were enhanced during the follicular phase (p < 0.05). Sialic acid expression was elevated in secondary and tertiary microgrooves during the follicular phase (p < 0.001), with mucin-bound sialic acids showing spatial variation along the canal. Segment 4 exhibited the lowest sialic acid expression (p < 0.01). Reproductive phase by cervical segment interactions affected both the secondary, tertiary microgroove epithelium, and surrounding luminal region adjacent to the tertiary microgrooves (p < 0.001). In conclusion, this study provides a detailed characterisation of the microarchitecture of the ovine cervical canal which is critical to understand the mechanisms orchestrating sperm transport. • Squamous epithelium found within the sheep cervix • Cervix cellular height increased during the follicular phase • Cervix microgroove tortuosity increases towards the uterine end of the cervix • Lectin binding maps mucus-rich regions within the sheep cervix epithelium • Mucus composition changes with reproductive phase, aiding sperm passage

Source: Theriogenology

DOI: 10.1016/j.theriogenology.2026.117828

Authors: N. Johnston, E. Bini, E. Fitzpatrick, C. Reid, S. Fair

Institutions: University of Limerick, University College Dublin

Language: English

Topic: Reproductive Physiology in Livestock

Subfield: Agronomy and Crop Science

Field: Agricultural and Biological Sciences

Domain: Life Sciences

Open Access status: hybrid

Estimated APC paid: $4,360

Funder: Department of Agriculture, Food and the Marine, Ireland