Development of Hysteroscopic Insemination of the Uterine Tube in the Mare

was found to be less than 2 French. The average volume required to fill a uterine tube was 0.3 ml. Complete tracts (n 5 86) were classified as estrus, diestrus, transitional, or anestrus based on ovarian structures. The external appearance of the ostium (opening) was imaged by using an Olympus stereomicroscope a connected to a data-acquisition‐dataanalysis imaging program. b The mean diameter and area of the ostium were determined. A variability in the external morphology but not in the diameter (analysis of variance; p 5 0.25) or area ( p 5 0.39) of the uterine tube was observed, but it was unrelated to physiologic status (chi square; p 5 0.56). There were five main morphologic categories: papilla (36%), complex (32%), diffuse (17%), double ridge (11%), and other (4%). There was a withinmare variability in morphologic type. In the second experiment, 12 mixed-breed light horse mares were selected for a breeding trial based on the following: age (,8 years of age), good endometrial biopsy scores (I or IIA), healthy reproductive tracts, and no history of reproductive problems. The mares were teased