Right Oviduct Fertility Studies

Transcription

1 Right Oviduct Fertility Studies WALTER MORGAN, PH.D. DESPITE the early anatomical bilateral potential of the reproductive system in the chicken, most females ultimately have only one functional ovary (the left) and one functional oviduct (also the left) when adults. Since the discovery that double oviducts, or persistence of the right oviduct, may be inherited 6 and that double oviducts may be identified in the living hen, 7 many questions have arisen concerning the influence of the right oviduct upon reproduction. Are eggs laid from both oviducts? If all or part of the semen enters the right oviduct at the time of natural mating, is fertility as high as when semen enters only the left oviduct? Can the ova from the left ovary be engulfed with equal ease by either the left or the right infundibulum? Can ova be fertilized by semen introduced through either oviduct, or must the mating be consumated only through the left oviduct opening? The purpose of this report is to answer the last of these questions and to shed light on others. PROCEDURE Inasmuch as the double-oviduct hens have only a left ovary8 there can be no ovulation from a right ovary into the right infundibular area. Identification of fertile eggs, resulting from inseminations into the right oviduct only, would suggest one of the following possibilities: (1) occasional engulfing of ova from the left ovary by the right oviduct, or (2) a posteriad migration of the semen to the cloacal area-followed by an anteriad migration into the functional left oviduct. Viable sperm were introduced into the right oviducts of double-oviduct hens in an effort to determine whether fertility resulted. Breedings Tests Twenty-three hens, which were identified as double-oviduct by the technic described by Morgan and Adams, were placed in individual wire cages. The hens were moved to the cages from floor pens which were From the Division of Animal Science, South Dakota State University, Brookings, S. D. 268

2 VOL. 19, No.2, 1968 THE RIGHT OVIDUCT 269 without males. Thhteen laying hens were artificially inseminated on Nov. 18 and Nov. 23 with semen collected from White Leghorn males of proved fertility. Approximately 0.2 cc. of undiluted semen was drawn into a 1.0-cc. tuberculin syringe, the syringe was then placed in the right oviduct of each hen and the semen was discharged. A total of 26 inseminations were made into the right oviducts. Eggs were individually identified when collected. Two settings of eggs, 1 week apart, were incubated. All eggs which were saved were laid no sooner than the second day after the initial insemination. At the time of incubation, the oldest eggs were approximately 7 days old. In all, 71 eggs were incubated from hens which were inseminated in the right oviduct (Table 1). On Nov. 30 and during the first week of Dec., the same hens were inseminated with semen from the same males-but into the left oviducts. The previously described procedure for saving and setting eggs was used for this phase of the experiment. In all, 44 eggs were set from the doubleoviduct hens which were inseminated with White Leghorn semen in the left oviduct during Dec. (Table 1). At the same time, double-oviduct hens which had not been laying in Nov. were inseminated with semen from Rhode Island Reds. Fertility resulting from this mating occurred 66 times (Table 1). Concurrently, semen from the White Leghorn males was inseminated into normal, single-oviduct hens during Nov. and Dec. A total of 152 eggs were incubated from this group of tester hens. From the results in Table 1, it is evident that semen which was introduced into the right oviduct was unable to fertilize ova. A careful examination of possible physical barriers within the body cavity followed. Anatomical Studies For the purpose of anatomical studies, double-oviduct hens were killed and placed on their backs. Incisions between the body and thighs freed the legs so that they could be bent downward to give the body bilateral support. The skin was cut near the vent to permit removal of skin and feathers from the entire ventral surface. Lateral incisions were then made TABLE 1. Fertility Resulting From Artificial Insemination Right Oviduct Left Oviduct Sire Dam Eggs set Fertile % Eggs set Fertile % R DOR WL DOR WL SOT R indicates Rhode Island Red Roosters; DOR, phenotypically double-oviduct Red hens; WL, tester roosters; and SOT, Single oviduct-tester hens.

3 ~10 MORGAN FERTILITY & STERILITY approximately 15 mm. on each side of the breast and continued through the ribs, permitting a lifting of the sternum and attached portions. Compact visceral contents occupied most of the body cavity. A ventromedial mesentery extended from the viscera to the medial sternal area. Hyman regarded the ventral mesentery as being composed of the ventral and falciform ligaments. Removal of the breast ruptured the mesentery. Dorsal to the medial sternal area were the liver lobes. Next posteriad in the body cavity, and protected ventrally by the posterior portion of the sternum and the breast, was the gizzard. The proventriculus extended anteriorly from the gizzard and dorsal to the left liver lobes. Intestinal loops around the lateroposterior perimeter of the gizzard were attached by fat and mesentery. Additional mesentery enclosed and supported the intestines. Dorsal to the intestinal mass was a medial mesentery which appended along a dorsal line between the right and left kidneys. McCleod referred to this as the "great mesentery." Ventrally, the dorsal mesentery was attached to the colon and extended from the cloaca and adjacent small intestine anteriorly to the spleen and liver. Thus the mesentery divided the two sides of the body cavity in the area of the gonads. An additional barrier was formed by the bilateral air sacs, each with two walls. In each hen, therefore, there was an effective barrier separating the right and left sides of the body cavity. Dorsally, the great mesentery extended to the viscera and intestines which, with their attached mesenteries, were joined ventrally by the ventromedial mesentery, which extended to the sternum. DISCUSSION Double-oviduct hens in the Rhode Island Red strain used for this study had right oviducts which were comparable tq the functional left oviducts. At autopsy, the right oviducts of laying hens were shown to be nearly the same length as those on the left side. The infundibular areas were not occluded but were structurally similar to those of the left oviducts, and would presumably be receptive to nearby ova. It was obvious that a sufficient physical barrier, particularly of the great mesentery and of the intestinal mesenteries, prevented migration of ova from the left ovary to the right side of the body. That answered two of the previously posed questions: (1) completed eggs were not formed in the normal-appearing right oviducts and (2) ova could not be fertilized in the right oviducts. Investigations concerning the ability of the right oviduct to effectively add the albumin layers, the shell membranes and the shell could be undertaken by making an incision in the right side of the body and inserting a yolk-like

4 VOL. 19, No.2, 1968 THE RIGHT OVIDUCT 271 object into, or near to, the infundibulum. An alternative would be to surgically sever the great mesentery and occlude the anterior end of the left oviduct so that the ova produced by the left ovary would be engulfed by the right infundibulum. The classical description of sperm movement is that the sperm move anteriad in the oviduct and unite, in the infundibular area, with the newly ovulated ova. The ova become fertilized prior to the addition of albumin to the forming egg. Recently the California groupl.9 has studied sperm movement and sperm concentration in the left oviduct of the hen. It is not surprising that the sperm (as indicated by negative fertility results reported in Table 1) which were inseminated into the right oviduct did not return posteriad to the cloacal region for movement and subsequent fertility in the left oviduct. Examination of tissues showed no sperm in the left oviducts of hens which were inseminated on the right side. Structural features of the chicken permit fertility only on the left side and the sperm do not migrate from one oviduct to the other. These findings are unrelated to the peculiar unilateral implantation observed in Sylvicapra grimmia by Child and Mossman. Infertility results from insemination into the right oviduct (Table 1) and it is conceivable that at copulation, in natural Hoor matings, the semen might enter the right, rather than the left oviduct of double-oviduct hens.. The result would obviously be infertility. When two oviduct openings are observed by a person practicing artificial insemination, the syringe should always be inserted into the left opening to insure maximum fertility. Artificial insemination is used widely in turkey production. 4 With the serious present-day fertility and parthenogenetic problems in turkeys, it is particularly important for the inseminator to introduce the semen only into the left oviduct opening for best results. From the practical standpoint, we could not expect double-oviduct hens to lay more eggs than single-oviduct hens unless an additional mutation for providing a right ovary could be incorporated into the breeding stock. Approximately 24 hr. are normally required for the egg to he completed after the initial ovulation. The present study indicates that mere selection for an increased ovulation rate would not result in more than one egg per day in the double-oviduct stock because the ova cannot cross the body cavity and be engulfed by the right infundibulum. SUMMARY Rhode Island Red laying hens which had two oviducts were artificially inseminated with semen from potent roosters. When the semen was in-

5 272 MORGAN FERTILITY & STERILITY troduced into the left oviduct, fertility was 82%; when introduced into the right oviduct, there was no fertility. It is concluded that the physical barriers present in the body cavity of the hen (the dorsal mesentery, the viscera, and the ventral mesentery) effectively prevent passage of ova from the left to the right side and that sperm do not migrate posteriad in the right oviduct to subsequently enter and fertilize ova in the left oviduct. South Dakota State University Poultry Science Department Brookings, S. D REFERENCES l. BOBR, L., LORENZ, F. W., and OGASAWARA, F. X. Distribution of spermatozoa in the oviduct and fertility in domestic birds. J Reprod FertiI8:39, CmLD, G., and MOSSMAN, A. Right horn implantation in the common duiker. Science 149: 1265, HYMAN, L. Comparative Vertebrate Anatomy. University of Chicago Press, Chicago, JOHNSON, A. S. ArtiRcial insemination of turkeys. Canadian Deparbnent of Agriculture, Pub. 897, Ottawa, McLEOD, W. M., TROTTER, D. M., and LUMB, J. W. Avian Anatomy. Burgess, Minneapolis, MORGAN, W., and KOHLMEYER, W. Bilateral oviducts in hens. Nature 180:98, MORGAN, W., and ADAMS, A. Identification of two oviducts in live hens. Poultry Sci 38:861, MORGAN, W., and GREB, R. Genetic and evolutionary aspects of double oviducts in Gallus. Poultry Sci 38: 1454, VAN KRAY, H. P., OGASAWARA, F. X, and LORENZ, F. W. Distribution of spermatozoa in the oviduct and fertility in domestic birds: IV. J Reprod Fertil 11:257, 1964.