Abstract
Ultrastructural features of the secretory cells of the goat's oviduct were studied at the early follicular phase, the follicular phase, the early luteal phase, the mid-luteal phase, and the late luteal phase. The secretory cells began to regenerate at the early follicular phase. At the follicular phase, numerous secretory granules of various size and electron density were seen in the secretory cells. At the early luteal phase, maximum secretory activity by exocytosis was apparent especially in the ampulla. At the mid-luteal and the late luteal phase, many ampullar secretory cells had large cytoplasmic protrusions which often contained nuclei. The pinching-off of protrusion was observed at these phases. Apoptosis-like fragments were seen in the ampullar epithelium at the late luteal phase, when the secretory cells were atrophied.
