| 摘要 |
An injection apparatus for injecting and/or removing substances from subjects, such as avian eggs, includes an injection needle having a body portion and a tapered portion that terminates at a tip. A tube is attached to and extends around the injection needle in substantially concentric relationship therewith. The tube has an end portion positioned a predetermined distance from the needle tip. The tube end portion acts as a stop to limit the distance the needle tip can be inserted into a subject, such as an egg, through a membrane of the subject. A detector may be utilized to measure force exerted on a membrane of an egg by a stop attached to a needle. Force exerted on a membrane by a needle and/or by a needle and a stop attached to the needle may also be measured.
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