Kumazawa H
Department of Parasitology, Kochi Medical School, Japan.
J Parasitol. 1992 Jun;78(3):498-504.
To estimate the rate of shedding of the proglottids during normal development of Hymenolepis nana in mice, 2 parameters, i.e., egg production and fecal egg output, have been determined. Changes in the number of eggs/proglottid along the length of the worm showed that, not only in vitro but also in vivo, a considerable number of eggs is discharged in situ while the proglottids are still attached to the worm. The in situ egg discharge, however, accounts only for a small fraction of the eggs appearing in the feces, and it can be neglected in the estimation of the shedding of proglottids. In H. nana the larva rotates 90 degrees in the egg during its development. This seems to occur in a short period, quite in concert within each proglottid. The transition point (the proglottid where 50% of the eggs have begun rotating) can be a useful landmark to estimate the rate of proglottid shedding. Egg numbers at the transition points approximate the genuine egg production, because in situ egg discharge mostly occurs only after the proglottids have passed the transition point. The 3 processes, i.e., the rotation of the larva in the egg, the in situ egg discharge, and the shedding of proglottids, usually occur in an orderly way. However, on day 20 of infection, just before the worms are lost (or destrobilated), shedding of proglottids seems to be inhibited, whereas the other processes are apparently normal.(ABSTRACT TRUNCATED AT 250 WORDS)
为了估计微小膜壳绦虫在小鼠体内正常发育过程中节片的脱落率，已确定了两个参数，即产卵量和粪便中的虫卵排出量。沿虫体长度方向每个节片的虫卵数量变化表明，不仅在体外，而且在体内，相当数量的虫卵在节片仍附着于虫体时就原位排出。然而，原位排的卵仅占粪便中出现的虫卵的一小部分，在估计节片脱落时可以忽略不计。在微小膜壳绦虫中，幼虫在卵内发育期间会旋转90度。这似乎在短时间内发生，在每个节片内相当一致。过渡点（即50%的虫卵开始旋转的节片）可作为估计节片脱落率的有用标志。过渡点处的虫卵数量接近实际产卵量，因为原位排的卵大多在节片经过过渡点后才发生。幼虫在卵内的旋转、原位排的卵以及节片的脱落这三个过程通常有序发生。然而，在感染后第20天，就在虫体消失（或脱节）之前，节片的脱落似乎受到抑制，而其他过程显然正常。（摘要截短于250字）
