Margaret Ward Orsini

Effect of Varying Doses of Progesterone on Implantation in the Ovariectomized Hamster.

Summary No delay in implantation was obtained in hamsters castrated on the second day of pregnancy and given daily doses of progesterone (2-.25 mg). Percentage of implantation obtained decreases as the dose level is lowered to .125 mg daily. At .0625 mg nidation may occur, but, in the majority of cases it either fails or resorption subsequently occurs. Nidation does not take place when .0312 mg is given.

Nidation in Progesterone-Treated, Estrogen-Deficient Hamsters, Mesocricetus auratus (Waterhouse).

Summary 1. In the hamster, when ovarian hormones are lacking, due to ovariectomy, or hypophysectomy, implantation does not occur and blastocysts are not recovered. 2. Implantation does not occur in hypophysectomized hamsters with pituitary autografts. 3. Doses of progesterone, 2-4 mg daily, do not affect time of implantation in the intact hamster. 4. Implantation occurs with no apparent delay in hamsters made estrogen-deficient by ovariectomy, ovariectomy and adrenalectomy, or hypophysectomy and given daily injections of 2-4 mg progesterone. In experiments designed to eliminate estrogen in injection media and diet, implantation also occurred when progesterone was given to ovariectomized hamsters. This suggests that progesterone alone is required for maintenance of blastocyst and nidation in the hamster.

Estrogen synthesis and metabolism in the hamster blastocyst, uterus and liver near the time of implantation

The steroidogenic potential of hamster tissues, just prior to implantation of the blastocyst in the uterus, was characterized by incubating blastocysts (14) and pieces of endometrium with [1, 2-3H]-androstenedione for 24 h. [3H]-2-Methoxyestradiol was synthesized, but intermediate estrogens were not found. To obtain a more quantitative assessment and comparison of steroidogenic activity, especially aromatase activity, in these tissues as well as in the uterine myometrium and liver and to increase the possibility of recovering estradiol, microsomes were isolated from 244 blastocysts and portions of the other tissues. Microsomes were incubated with [1 alpha, 2 alpha-3H]-testosterone plus [1 beta,2 beta-3H]-testosterone for 6 h. During this time [3H]-metabolites were synthesized by all tissues as indicated by HPLC. [3H]-Androstenedione was noted and values were higher than control levels (medium alone or microsomes from uterine flush fluid) in all samples but liver. [3H]-Estradiol was detected at an elevated level only in the blastocyst sample; however, addition of unlabeled estradiol during the subsequent incubation of endometrial, myometrial and liver microsomes increased the recovery of [3H]-estradiol. Identities of [3H]-2-methoxyestradiol from the first experiment and [3H]-androstenedione and [3H]-estradiol from the second experiment were confirmed by recrystallization. The formation of 3H2O from [beta-3H]-testosterone was used as an index of aromatase activity. After subtracting control medium values, blastocysts were 24-fold more active (dpm/microgram protein) than the endometrium and myometrium in synthesizing 3H2O. While there was no difference in synthetic potential between endometrium and myometrium, aromatase activity in these tissues was greater than that of the liver. Microsomes from uterine flush fluid displayed no capacity for synthesizing 3H2O indicating that the elevated blastocyst levels were not caused by contaminating endometrial cells. These results indicate that all of the tissues examined have the capacity to metabolize C19-steroids to a variety of hormones, including estrogens, and further, that estrogen metabolism occurs rapidly in these tissues. This capacity may be important for providing a suitable hormonal milieu at the time of implantation.

Ontogenetic Aspects of Sexual Dimorphism and the Primary Immune Response to Sheep Erythrocytes in Hamsters from Prepuberty through Senescence

Ontogeny of the primary response to sheep erythrocytes of age-matched groups of male and female hamsters was studied at various chronological ages ranging from prepuberty to senescence. Selected organs were likewise weighed upon sacrifice to obtain developmental patterns. Adrenal weights were higher in the male, and pituitary weights were higher in the female; for both organs typical dimorphism was demonstrable by 36 days. Spleen weight and index favored the female by 46 days. Immunological sex dimorphism first appeared in groups injected at 53 days and autopsied at 58 days and persisted through senescence. Sexual dimorphism of antibody-mediated immunity, previously shown to favor the female in both the primary and secondary immune responses, thus follows the dimorphism of total amount of splenic lymphoid tissue and occurs shortly after realization of sexual maturity in the male. These findings support our previous suggestion of the suppressive effect of androgens on the antibody-mediated immune responsiveness of the male hamster.

Sexual Dimorphism in the Primary Immune Response of the Syrian Hamster

The primary immune response patterns of young adult male and female hamsters injected with SRBC cells were studied and compared. The females were shown to produce higher numbers of PFC per spleen than

Changes in Tissue Histamine During the Estrous Cycle, Pregnancy and Pseudopregnancy in the Golden Hamster

Abstract The histamine content of reproductive tissues and skeletal muscle was determined in the golden hamster during the estrous cycle, pregnancy, and pseudopregnancy. Histidine decarboxylase activity was measured in uterine implantation sites and intersites from Day 4 to Day 10 of pregnancy. Histidine decarboxylase was also measured in mesometria and placentas on selected days of gestation. During the estrous cycle, uterine and skeletal muscle histamine levels were highest on Day 2 and lowest on Day 4 of the cycle. The ovarian histamine content did not change significantly among the different stages of the cycle. While the histamine content of uterine implantation sites of attachment was high on Days 4 and measurable on Days 5 and 6 of pregnancy, the levels were below the limits of detection by Day 7. On the other hand, the highest levels of histamine were in the uterine interimplantation sites on Days 8 and 9. The ovarian levels of histamine were highest on Day 13 of pregnancy. Histamine in skeletal muscle did not change significantly during pregnancy. The histidine decarboxylase activity in the implantation sites began rising on Day 9 and increased dramatically on Day 10. Placental histidine decarboxylase activity was very high on Days 13 and 15. Overall, we observed changes in uterine and skeletal muscle histamine during the estrous cycle that may be explainable in light of previously reported changes in mast cell numbers and circulating estrogens. During pregnancy, histamine levels of implantation sites and implantation intersites varied, as did the histamine content of ovarian tissue. Histidine decarboxylase activity rises in the uterus and placental tissue after the formation of the placenta.

Comparative ultrastructure of the decidua in pregnancy and pseudopregnancy

Abstract The ultrastructural development of decidua in pregnant hamsters and in deciduomas of equivalent age are compared during the period of 3 days beginning 5 days and 19 hours after ovulation. At first, the decidua produced in response to the blastocyst resembles in detail that of the deciduoma caused by injection of air into the pseudopregnant uterine horn. Although the decidua in true pregnancy maintains its characteristic ultrastructural features, the first signs of degeneration within the deciduoma are detectable as early as 6 days and 19 hours after ovulation. This tissue may show mitoses and regressive changes simultaneously. By 7½ days after ovulation, degeneration of the deciduoma is advanced. Beyond that period, ultrastructural details are obliterated. Thus, by the time that a typical pericellular deposit has formed around the decidua in true pregnancy, the deciduoma has begun to deteriorate. The role of the trophoblast in inducing deposition of this capsular material therefore could not be evaluated in these experiments. The two triggering mechanisms, blastocyst and injection of air, induce a common pathway of decidualization in the progesterone-stimulated uterus.

Localization of glycogen in the opacity characterizing decidualization in the cleared hamster uterus.

Uteri of pregnant hamsters, and of pseudo-pregnant hamsters in which decidualization has been induced, reveal areas of opacity when viewed by oblique light after clearing by the benzyl-benzoate process. These opacities have been shown to be associated with decidua(1–3), and the presence of glycogen in them has been suggested(2). During gestation, the first of these areas which appear opaque after clearing develop coincidentally with decidua and mark implantation or decidualization regions prior to visible external swelling. They increase in mass, distending the uterus as localized swellings, late on the sixth day of gestation. They reach a peak in terms of mass per conceptual swelling on the seventh day of development, and begin to regress from the antimesometrial area on the eighth day, i.e., at 7 days and 12 hours. This paper reports results of chemical analyses of these tissues in comparison to the remainder of the uterus. Materials and methods. At the relative peak of development of the areas in question (sixth and seventh days), it is possible to make a transverse slit in the uterus at the swollen gestational sites and, with fine forceps, peal from the endometrium the denser mass of the embryo and its surrounding decidua. Examination of material separated by the above technique and then cleared, showed that the peeled out region comprised almost all the opaque material (Fig. 1 and 2). Such “peeled out regions”subsequently are referred to as “opacities,”whether or not they have been subjected to the clearing process and thus actually appear opaque. Samples of the remaining portions of the uterus, from which all mesometrium was removed, were analyzed for comparison. One series of determinations was carried out on material which had been cleared prior to the separation of the opaque regions.