CYCLIC HISTOLOGICAL-CHANGES OF THE OVIDUCTAL-CLOACAL JUNCTION IN THE VIVIPAROUS SNAKE TOLUCA-LINEATA

The structure and seasonal changes of the oviductal-cloacal junction r emain poorly understood in most squamates. This study was undertaken t o describe the histology of the oviductal-cloaca junction of a female viviparous snake Toluca lineata, during gestation, previtellogenesis, and vitellogenesis. The oviductal-cloacal junction exhibits a wider lu men and thicker layers of connective tissue, smooth muscle layers, and total wall width compared to the posterior vagina. The lining is char acterized by thick, short longitudinal mucosal folds. The luminal epit helia differ morphologically from anterior to posterior portions of th e oviductal-cloacal junction. The anterior portion is lined with a sim ple columnar epithelium composed of nonciliated cells. The middle port ion is lined with stratified epithelium that contains an apical column ar cell layer that undergoes morphological changes coincident with the reproductive cycle. The posterior portion is lined with a stratified squamous epithelium. The connective tissue underlying the epithelium c ontains numerous ovoid cells having abundant acidophilic cytoplasmic g ranules-eosinophils. Copulation occurs during the previtellogenic stag e, as evidenced by the presence of abundant spermatozoa in the lumen o f the anterior portion and of a copulatory plug in the middle and post erior portion of the oviductal-cloacal junction. J. Morphol. 237:91-10 0, 1998. (C) 1998 Wiley-Liss, Inc.