Determination of reproductive maturity in the female nine-banded armadillo (Dasypus novemcinctus).

At 3-month intervals from birth to 27 months of age, 3 female armadillos were killed. The number and size of follicles greater than 202 micron were determined, plasma progesterone concentration was measured, and values were correlated with age. Blood samples were taken monthly by femoral vein puncture and plasma was analysed by radioimmunoassay for progesterone concentration. At necropsy, both ovaries were visually inspected for a corpus luteum, weighed and then processed for routine histology. The number of normal, antral follicles greater than 202 micron were counted. These follicles were arbitrarily categorized into 15 different size groups (every 77 micron). Total number of follicles greater than 202 micron varied from 15.5 +/- 1.3 at 15 months of age to 26.3 +/- 1.9 at 21 months. Follicles of a size (greater than 978 micron) most likely to ovulate were present only at greater than or equal to 9 months of age. Progesterone values remained below the adult concentration (5 ng/ml) until 15 months of age. A concentration of progesterone indicative of ovulation (approximately 10 ng/ml) occurred between 17 and 20 months of age. The findings of the present study demonstrate that the female armadillo is reproductively mature after 15 months of age.

Evaluation of simultaneous teaching of extremities in gross anatomy program.

A gross anatomy program was designed to expose medical students to all areas of the body but shortened the dissection time on the extremities by having half the class dissect either the upper or lower extremity and then study the opposite extremity already dissected by other classmates. The program has been used for six years and was evaluated via an analysis of covariance by comparing the intramural examination performance on both the dissected and undissected extremities. There was no statistical difference in the students' performances regardless of the extremity dissected. The program was also evaluated externally by student performance on Part I of the examinations of the National Board of Medical Examiners. Students (n = 191) performed at the national average (69 percent) on all gross anatomy questions and on those questions pertaining to either extremity (66 percent). The program has efficiently utilized laboratory time with no measurable change in performance by six medical classes.

Cross-sectional anatomy: preparation of teaching specimens.

Forty cross sections of a male cadaver were prepared for a Continuing Medical Education Seminar and have been used in teaching programs for the past 3 years. The sections are easy and inexpensive to construct and can be maintained with a minimal amount of effort.

Adrenalectomy has a differential effect on the ovarian response of two strains of rat.

Evidence indicates that the ovarian regulatory mechanism of different strains of rat may respond differently to adrenalectomy; this study examined that possibility. Adult female Sprague-Dawley and Holtzman rats were maintained under constant environmental. Adult female Sprague-Dawley and Holtzman rats were maintained under constant environmental conditions and each strain was divided into groups: intact; adrenalectomized; unilaterally ovariectomized; adrenalectomized and unilaterally ovariectomized for 30 days; adrenalectomized 30 days previously and then unilaterally ovariectomized followed by one oestrous cycle; adrenalectomized 30 days previously and then unilaterally ovariectomized followed by one oestrous cycle with progesterone treatment (2 mg); adrenalectomized 30 days previously and then unilaterally ovariectomized followed by one oestrous cycle with corticosterone treatment (2.5 mg/100 g). All operations and autopsies were performed at metoestrus. Chronically adrenalectomized rats shed fewer ova per ovary than intact animals. Rats that had been unilaterally ovariectomized or adrenalectomized and unilaterally ovariectomized for 30 days showed conpensatory ovulation as compared with intact rats and rats adrenalectomized for 30 days. Only the Sprague-Dawley rats that were adrenalectomized for 30 days and unilaterally ovariectomized for one oestrous cycle demonstrated compensatory ovulation. The remaining ovary in similarly treated Holtzman rats failed to compensate. Neither progesterone nor corticosterone influenced compensatory ovulation in the Sprague-Dawley rats, but both hormones caused an increase in the number of eggs ovulated in the Holtzman animals. In conclusion, the results of this study indicated that there is a strain-specific responsiveness of the ovary to adrenalectomy as assessed by compensatory ovulation.

Clomiphene-induced ovulation in the 9-banded armadillo (Dasypus novemcinctus).

8 armadillos each received 50 mg clomiphene citrate daily for 5 days. 7 of the animals showed an increase in plasma progesterone to a level indicative of ovulation (greater than 10 ng/ml) within 6 days of the last injection. In addition, the administration of clomiphene caused the urogenital smear pattern to change from dioestrous to oestrous.

Quantitative investigation of the annual pattern of follicular development in the nine-banded armadillo (Dasypus novemcinctus).

Mature, non-pregnant, female armadillos (Dasypus novemcinctus) were killed throughout the year (3-6/month, N = 54) and both ovaries were examined for follicular development. All normal and atretic follicles > 358 micrometers were counte. Total number of normal follicles remained constant from January to June but decreased by 50% in the remaining months except in October and November. Follicles > 978 micrometer (those likely to be ovulated) were found during each month but more (> 3/ovary) were present during April, May, June and October. Atretic follicles remained constant (4-6) except in July and August when the number (10-12) was doubled. A single CL was present in 2/4, 6/6, 1/6, 1/3 and 2/3 animals in July, August, October, November and December, respectively. These data confirm that armadillos ovulate in July and suggest that ovulation may also occur in some animals in late October or November.

Plasma progesterone level during delayed implantation, gestation and postpartum period in the armadillo.

Blood samples were obtained weekly from 21 pregnant armadillos during the months of June through May and analyzed by radioimmunoassay for progesterone concentration. Following ovulation and mating, the plasma concentration of progesterone remained elevated (greater than 13 ng/ml) during the 3.5 months of delayed implantation. As implantation occurred in October, the plasma concentration of progesterone increased and remained at approximately 20 ng/ml in all animals through March. Ten of the animals delivered during March and April in captivity. The date of the blood sample collection was calculated as the number of days before or after parturition. Progesterone concentration was not decreased prior to delivery and remained elevated for as long as 55 days following parturition.

The effect of amygdaloid and hippocampal lesions on compensatory ovulation and pro-oestrous gonadotropin levels in the rat.

The purpose of this study was to examine the effects of limbic forebrain lesions in conjunction with unilateral ovariectomy (ULO) on compensatory ovulation. At metoestrus, cyclic rats were ULO and bilateral brain lesions were placed in either the cerebral cortex (CTX), dorsal hippocampus (DHPC), amygdaloid nucleus (ACO) or stria terminalis (ST). In addition, two control groups consisted of intact and ULO only rats. Plasma samples were obtained at the subsequent pro-oestrus and analyzed by radioimmunoassay for FSH and LH. All animals were killed at the next metoestrus and the number of eggs shed were determined. After ULO alone, twice as many ova as normal were shed from the remaining ovary. Ovulation was inhibited in 30% of the ACO- and ST-ULO animals and damage to either the DHPC, ACO or ST caused a delay in time to the post-lesioned ovulation. However, all animals in the four brain lesioned-ULO groups that did ovulate doubled the number of eggs shed. Pro-oestrus plasma levels of FSH and LH did not differ between animals in the six groups. Thus, while amygdaloid lesions may alter certain parameters of pituitary ovarian function, the limbic forebrain is not involved in the mechanism of compensatory ovulation.

Failure of a synthetic, anti-inflammatory compound to alter the efficiency of the IUD.

Holtzman, female rats with a plastic or copper IUD were maintained on either a dexamethasone solution (9.4 or 28 micrograms/rat/day) in the drinking water or on water alone. Animals were caged with males of proven fertility and subsequently killed at day 14 of pregnancy and the number of implantation sites counted. Both types of IUDs were effective in preventing implantation. Implantation sites were not increased in dexamethasone-treated animals. In addition, proestrous gonadotropin levels and follicular development did not differ between treated and nontreated animals. Thus, the data demonstrate that the efficacy of the IUD is not decreased with the use of anti-inflammatory drugs.

Effect of spinal cord transection on the reproductive system in the female rat.

Cycling rats had their spinal cord transected (SCT) at the T5 vertebral level and/or were unilaterally ovariectomized (ULO) at metestrus, and allowed to cycle either for one estrous cycle or for 19 days. Estrous cycle lengths were increased following SCT in all animals. After one cycle, SCT rats showed no effect on other reproductive parameters studies. In contrast, after 19 days decreases in body and ovarian weights, and number of follicles greater than 448 micrometers and ova shed per ovary were observed. When ULO was performed in conjunction with SCT, compensatory ovarian responses occurred. The data demonstrate that an intact adrenergic system is necessary for normal ovarian function in the intact rat but not necessary for compensatory ovarian responses to occur following ULO.

Effect of oral contraceptive used by technician on sensitivity of progesterone radioimmunoassay.

Gonadotropin and steroid radioimmunoassays (RIAs) have been run in our laboratory for the past 6 years. Recently, the progesterone RIA was unpredictable when performed by one technician. After checking the mechanics and reagents, it was discovered that the technician had changed from Ortho Novum 1 + 50 to Ovral about the time the RIA became erratic. Standard curves of progesterone RIAs performed while the technician was taking either Ortho Novum 1 + 50 or Ovral, or on no contraceptive are reported. The data suggest that a probably exhaled metabolic product of norgestrel, the synthetic progestin in Ovral, interferes with the progesterone RIA and indicate an additional variable investigators must eliminate in performing RIAs.

Potencies of oral contraceptives.

PIP: This letter is a response to the discussion by Edgren and Sturtevant (125:1029, 1976) on potencies of oral contraceptives (OCs). It is agreed that the results of studies in animal models on OC potencies may not necessarily reflect true potencies in human subjects, however, these animal models do allow the evaluation of the biological effects and interactions of the components of OCs. Data obtained in animal studies are acknowledged to be valuable aids in the study of human diseases. Likewise, mouse uterine response to contraceptive steroids is 1 criterion to be used in evaluating steroid potency. As previously reported, the importance of the mouse uterine response is that the contribution of the progestin component to the total estrogenic potency of the OC is demonstrated.^ieng

Intracellular collagen in the nonpregnant and IUD-containing rat uterus.

An experiment designed to study the effects of the copper IUD on the virgin rat uterus has revealed the presence of intracellular collagen fibrils in control uteri and in uteri that have contained a copper IUD for three months. The cells containing the collagen are found in the stroma in close proximity to the uterine epithelium. The collagen is found within membrane-bound cytoplasmic vacuoles that vary in morphology. In some cases the fibrils are tightly packed and linear, with no other material evident in the vacuole. In other examples, the fibrils are randomly arranged and the vacuoles contain a punctuate material which is characteristic of phagolysosomes. Finally, cytoplasmic vacuoles are seen which contain ill-defined debris and poorly-visualized structures that exhibit a periodicity, suggesting a terminal phase of fibril breakdown. All animals were sacrificed in metestrus, and the results indicate that intracellular collagen is present in the nulliparous rat uterus at this stage of the cycle. In addition, this phenomenon does not appear to be influenced by the presence of a copper IUD over a period of three months.

Autonomic innervation and plasma estradiol-17beta and progesterone levels in rats with subcutaneous ovarian autografts.

Ovaries were removed from female rats and immediately autografted into a subcutaneous pouch in the flank in order to quantitate the relationship of graft re-innervation, steroid secretion and vaginal smear pattern. Animals were killed at thre time periods: three days after grafting, on the first day a cornified vaginal smear appeared and at the first metestrus. In addition, control animals were killed at metestrus. Plasma samples were obtained from all rats and analyzed for estradiol-17beta and progesterone concentration by radioimmunoassay. At the first day of vaginal cornification after grafting, plasma estradiol-17beta (45.8+/-4.0 pg/ml) was elevated in comparison to controls at metestrus (24.0+/-2.6 pg/ml), but plasma progesterone (21.5+/-4.0 ng/ml) was not different (30.6+/-1.7 ng/ml). Subsequently, at the first metestrus following grafting, plasma estradiol-17beta (23.0+/-3.5 pg/ml) was comparable to control values. In contrast, progesterone was decreased (17.5+/-1.9 ng/ml). A definite correlation was detected between the vaginal smear and plasma levels of steroid hormones in the castrated female rat with subcutaneous ovarian autographs Histochemical techniques were used to study the adrenergic and cholinergic innervations of grafts three days after grafting, at the first day of vaginal cornification, and at the first metestrus. No correlation was shown between density of adrenergic or cholinergic innervation and plasma levels of estradiol-17beta and progesterone or onset of a cycling vaginal smear.