Gene Oliphant

Removal of Sperm-Bound Seminal Plasma Components as a Prerequisite to Induction of the Rabbit Acrosome Reaction*

When rabbit sperm were pretreated with media of high ionic strength (380 mOsM), which had previously been shown to facilitate removal of sperm-bound seminal plasma components, and subsequently treated with follicular fluid the acrosome reaction was completed rapidly. Treatment of the sperm with follicular fluid alone yielded a greatly decreased rate of acrosome reaction completion, and treatment with the high-ionic strength medium alone caused no visible alteration to the sperm. These results suggest that removal of the sperm-bound seminal plasma components destabilizes the acrosome and prepares it to undergo the acrosome reaction. This destabilization is virtually completed after a 5-minute preincubation of the sperm in high-ionic strength media. Direct comparison of epididymal and ejaculated sperm indicated that epididymal sperm acrosomes were apparently in the same stabilized condition as ejaculated sperm. The effect of the pretreatment by high-ionic strength media could be partially mimicked by pretreatment of sperm with alpha- or beta-amylase or neuraminidase but not by beta-glucuronidase, lipase, pronase, or trypsin. Comparison of the ability of bovine follicular fluid, rabbit follicular fluid, and rabbit serum to induce the rabbit acrosome reaction showed that bovine follicular fluid was 3 to 4 times more effective than rabbit follicular fluid and that rabbit serum was totally ineffective in producing the acrosome reaction. The data support a physiologic role for follicular fluids in the process of fertilization and indicate that removal of sperm-bound seminal plasma components is a prerequisite to efficient induction of the acrosome reaction.

Collection of Gametes in Laboratory Animals and Preparation of Sperm for In Vitro Fertilization

Ova to be used for in vitro fertilization are routinely collected after superovulation. In small animals and depending on the species, 5–150 IU of pregnant mare serum gonadotropin (PMSG) is administered 2–4 days prior to an ovulating dose (5–125 IU) of human chorionic gonadotropin (hCG) (Yanagimachi, 1969; Iwamatsu and Chang, 1969; Barros et al., 1973; Brackett and Oliphant, 1975). Superovulation procedures, for example in rabbit, can produce as many as 60 ova per rabbit but will more commonly result in 20 ± 3.0 ova recovered from the oviduct. There is some evidence that superovulation may cause chromosomal abnormalities (Fugimoto et al., 1974; Maudlin and Fraser, 1977).

Development and evaluation of digitally processed Z-contrast imaging: a technological advance in medical imaging

For the first time in the field of medical imaging, harmonious use of Z-contrast imaging and digital image processing was developed as an analytical imaging tool and demonstrated in studying human and rabbit spermatozoa. The biological information generated is unique to the science of medical imaging. The versatility of its applications is wide as this advance in imaging technology can be applied to any area of medicine involving tissue analysis. Tissue analysis plays a vital role in both medical research and diagnostic patient care. Imaging in the Z-contrast mode of the scanning-transmission electron microscope affords biologists the capability to image tissue in its natural state such that heavy metal fixatives and stains are not used. The digitally processed Z-contrast image is not only devoid of artifacts caused by fluctuating mass-density, topography variations, and the addition of heavy metal contrast agents but also offers a biological blueprint of the atomic weight distribution in the tissue. The varying gray level intensities assigned to each pixel in the resulting image are specific to the average atomic weight differences inherent in the tissue. The advent of complementary Z-contrast imaging and digital image processing and their concomitant research possibilities offers areas of medical care and medical research an invaluable imaging tool.