Scanning electrons and light microscopy of the equine seminiferous tubule.

This research investigates the changes that take place in horse seminiferous tubules during the cycle of the seminiferous epithelium using light and scanning electron microscopy (SEM). The study revealed different morphological features in the cytoplasm of germ/Sertoli cells and flagella extensions into the tubular lumina at different stages of the seminiferous cycle.

Methodology

• The study used advanced microscopic techniques, including light microscopy and SEM, to study the equine seminiferous tubule.
• After observing the tubules with SEM, they were then sectioned and staged using light microscopy.

Findings in Early Stages

• The research uncovered certain characteristics in the early stages (I and II) of the seminiferous cycle. Here, the germ cells or Sertoli cells’ cytoplasm showed a weblike, spongy structure that expanded over the entire height of the germinal epithelium.

Findings in Later Stages

• In stages III-VIII, the cytoplasm in the basal portion of the germinal epithelium was found to be similar to that in stages I and II.
• A distinct trait was noted in the cytoplasm filling the luminal third of the epithelium in stages III-VII – it appeared smooth.
• By stage VIII, the smooth-surfaced, periluminal cytoplasm was observed to be diminishing.

Flagella and Sperm Formation

• The study also scrutinized the flagella extensions into the tubular lumina during different stages of the seminiferous cycle.
• Principal pieces of flagella from spermatids were found to extend into the tubular lumina at all stages, but the middle pieces only did so in stage VIII.
• In the later part of stage VIII, the middle pieces, engulfed with cytoplasm, linked to the germinal epithelium through stalks and ultimately played a significant role in sperm formation. The middle pieces’ diameter was similar to that of ejaculated spermatozoa after spermiation.
• Therefore, the study infers that the cytoplasm within these thickened middle pieces contributes to the formation of cytoplasmic droplets, which are vital in sperm production.