Effect of Anesthesia on Artificial Production of Pseudopregnancy in the Rat. ∗

Abstract

The condition of pseudopregnancy in the rat was first described by Long and Evans. 1 These authors demonstrated that pseudopregnancy could be produced artificially by the introduction of a small glass rod into the cervical canals at the time when the animal was in stages 1, 2 or 3 of the oestrous cycle, as specified by them. Wang 2 corroborated the findings of Long and Evans and recently Slonaker 3 has made additional contributions to the subject.

Long and Evans showed that there was no direct nervous connection between cervix and ovary. Slonaker suggests that a substance, most likely to be found in the vaginal or uterine mucosa, is responsible for the continued action of the corpora lutea in pseudopregnancy and possibly in pregnancy. He further suggests that this substance could act either directly on the corpora lutea or through some intermediary agency, possibly the anterior part of the pituitary gland. It has been shown by Smith, 4 Smith and Engle, 5 Evans and Simpson 6 and others that there are one or more substances secreted by the anterior portion of the pituitary body which influence the growth of follicles and the formation of corpora lutea of the ovary.

We wish to report results obtained when rats in the first 2 stages of the oestrous cycle are anesthetized for a short time with ether, nitrous oxide, or ethylene, and the cervical canals then stimulated by a small glass rod, as compared with controls which were not anesthetized. The rats used in this study were all healthy and sexually mature. A number of the animals were selected from the stock cages at the time when they were in oestrum, without first determining the regularity of their cycles.