Charles E. Hamner

Biochemistry and Physiology of Oviductal Secretions

The tubal environment holds a strategic location with respect to the reproductive processes. Histological visualization and biochemical analysis have shown that both oviductal tissue activity and fluid constituents are influenced by the hormonal state of the female. Also, tubal epithelial synthetic activity appears to be affected by the proximal embryo. The functional importance of differential oviductal secretions is presently unclear. However, the techniques of in vitro fertilization, embryo transfer, and culture aid in defining minimal developmental requirements and effects of cyclic secretions on embryologic events.

Capacitation of Rabbit Spermatozoa Species Specificity and Organ Specificity.

Summary It has been found that washed rabbit sperm may be capacitated in the uterus of an estrous rabbit, rat, and dog, indicating that the capacitation mechanism is similar in these species. It was shown that washed rabbit sperm are capacitated only in the uterus and oviduct of the estrous rabbit and not in the bladder, colon and knee joint, indicating that the factors necessary for capacitation are limited to the female reproductive tract.

In vitro fertilization of rabbit eggs in oviduct secretions from different days before and after ovulation.

In vitro fertilization of rabbit eggs in oviduct secretions has been studied through different days of the psudopregnant cycle. The appearance of the pronuclei and cleavage into two cells, which were the criteria of fertilization, occurred significantly less frequently when in vitro fertilization was attempted in the oviduct secretions obtained during the estrous (preovulatory) period of the cycle than it was in the secretions obtained during pseudopregnancy or in Bracketts medium plus 20% heated rabbit blood serum. Whether fertilization was attempted in ampulla secretions or in whole oviduct secretions had no effect on the success rate. The effects of oviduct secretions from the estrous period of the cycle is probably due mainly to an effect on the egg, involving the very first development processes during and after fertilization.

A Demonstration of Cat Seminal Plasma Antifertility Activity

Summary CSP has a reversible, partially heat-labile, antifertility effect on rabbit spermatozoa. In an in vivo fertilization assay for capacitation, CSP-treated sperm fertilize significantly fewer ova than do control sperm (P < 0.005). Heating the CSP to 60° for 10 min destroys some of the activity, while heating it to 100° for 10 min further attenuates it. In both cases, CSP-treated sperm still fertilize fewer ova than do control sperm (P = 0.005). CSP also contains partially heat-labile trypsin inhibitor activity which may be partially responsible for the antifertility activity. This work supported in part by Grant HD06573 and Career Development Award 12,760 to one of us (C. E. H.) from the USPHS.

Capacitation in the Rabbit: Stimulation, Inhibition, and Recovery from Inhibition

Summary The capacitating ability of the oviduct and uterus in the ovariectomized rabbit with and without estrogen treatment was compared. There was a significant decrease in the ability of the uterus and oviduct to capacitate sperm within 3 days after ovariectomy. Both the uterus and oviduct showed a biphasic response to estrogen. Optimum capacitation occurred when ovariectomized rabbits were given 0.5-1.0 μg ECP/kg/day. The ability of the uterus to recover after inhibition by progesterone was studied. The uterus requires about 10 days to return to its nontreated ovariectomized capacitating state after progesterone treatment is stopped. If estrogen is given when progesterone is stopped, the uterine capacitating ability is restored to the nontreated ovariectomized state in 24 hr. However, only after 10 days of estrogen treatment is optimum capacitating ability regained by the uterus.