middle piece

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a part or portion.
end piece the terminal portion of the tail of the spermatozoon. See illustration at spermatozoon.
middle piece an anterior portion of the tail of the spermatozoon, between the neck and the anulus. See illustration at spermatozoon.
principal piece the main portion of the tail of a spermatozoon, beginning at the anulus and gradually tapering toward the end piece. See illustration at spermatozoon.

mid·dle piece

a part of the spermatozoon characterized by an axoneme and by a sheath of mitochondria arranged in a tight helix.
References in periodicals archive ?
Sperms with abnormally forked nuclei and degenerating mitochondria in the middle piece were also noticed in these specimens (fig.
The tail is composed of a middle piece, principal piece, and end piece.
16] That is, by properly selecting the appropriate middle piece, and adjusting the plug and tuning slide.
The middle piece of the letter is missing, but after a few fragmented sentences, the third part concludes, 'Even if I hurt you thoughtlessly, if you will begin mocking me, let God judge you, and my weakness'.
Start by enlarging our patterns on paper and tracing the outlines onto the wood--one silhoutte of the larger middle piece (outlined) and two of the side pieces (shaded).
Tenders are invited for Middle Piece For N-32 Tap-Changer As Per M/S.