雌性恒河猴月经周期FSH、LH分泌水平的研究

本文采用改进的体外生物测定法分析恒河猴月经周期中促卵泡刺激素（ＦＳＨ）、促黄体生成素（ＬＨ）的变化情况。结果表明：雌猴的ＦＳＨ峰出现在月经周期的第１０２±１０天,峰值：５７２±４８ｎｇ／ｍｌ;ＬＨ峰出现在月经周期的第１２０±１６天,峰值：９６３±９７ｎｇ／ｍｌ,且为滤泡期、黄体期平均值的７～８倍。证实了在雌性恒河猴的月经周期中,其ＬＨ分泌高峰与ＦＳＨ分泌高峰不在同一时间出现的现象。     

恒河猴(Macaca mulatta)生殖周期内性类固醇激素分泌规律的研究

本文用放射免疫测定法对7只雌性恒河猴(Macaca mulatta)的20个月经周期进行了雌二醇、孕酮和睾酮的动态测定分析,其中15个月经周期的中期都有睾酮和雌二醇峰(其峰值分别为1010.7±411.3pg/ml和179.1±91.3pg/ml),孕酮在黄体期的峰值为2.54±0.65ng/ml。正常黄体期的血清孕酮水平不低于1ng/ml。20个月经周期的平均天数为28.6±5.4天,滤泡期和黄体期分别为11.9±2,6和19.2±6.3天。月经周期可用公式Y=18.92±0.03×X~2 (Y:月经周期,X:黄体期。R=0.9444)表示。实验结果表明,测定周期内三种性类固醇激素可以准确确定排卵。睾酮在生殖周期内的分泌调节机制还待进一步研究。     

恒河猴(Macaca mulatta)生殖周期内性类固醇激素分泌规律的研究

本文用放射免疫测定法对7只雌性恒河猴(Macaca mulatta)的20个月经周期进行了雌二醇,孕酮和睾酮的动态测定分析,其中15个月经周期的中期都有睾酮和雌二酮峰(其峰值分别为1010.7±0.65ng/ml. 正常黄体期的血清孕酮水平不低于1ng/ml. 20个月经周期的平均天数为28.6±5.4天, 滤泡期和黄体期分别为11.9±2.6和19.2±6.3天. 月经周期可用公式Y=18.92±0.03×X²(Y:月经周期,X: 黄体期. R=0.9444)表示.实验结果表明, 测定周期内三种性类固醇激素可以准确确定排卵.睾酮在生殖受气内的分泌调节机制还待进一步研究.     

芹菜素对雌性大鼠生殖轴的影响

目的：探讨芹菜素在10-9mol/L浓度时对雌性大鼠生殖功能的影响。方法：应用侧脑室注射方法观察芹菜素对雌性大鼠生殖轴激素含量的影响。在侧脑室注射后第3天取血浆,采用放免技术测定血浆中促性腺激素释放激素（GnRH）、卵泡刺激素（FSH）、黄体生成素（LH）、雌二醇（E2）、孕酮（P）的含量。结果：在给药后第3天血浆中促性腺激素释放激素（GnRH）、卵泡刺激素（FSH）、黄体生成素（LH）的含量增加而雌二醇（E2）、孕酮（P）的含量降低,差异有显著性。结论：芹菜素抑制雌二醇（E2）合成中芳香化酶的活性实现对雌二醇（E2）、孕酮（P）分泌的抑制。芹菜素通过影响雌激素受体而使下丘脑的促性腺激素释放激素（GnRH）和腺垂体的卵泡刺激素（FSH）、黄体生成素（LH）分泌增加。     

广州地区西藏小型猪的繁殖行为学表现

目的对广州地区西藏小型猪的繁殖性能和繁殖行为进行了观察研究。方法以广州地区雌雄西藏小型猪为研究对象,根据其繁殖卡的详细资料进行分类统计。结果雄性西藏小型猪阴茎首次伸出日龄为(39.50±2.63)d,此时体重为(3.26±0.87)kg;其射精日龄为(65.22±3.69)d,体重为(5.34±1.03)kg。雌性西藏小型猪初情日龄为(142±5.3)d,成年母猪发情周期为(20.35±0.72)d,发情持续期(4.2±0.31)d;其妊娠期约为114 d左右。初产雌性西藏小型猪产仔数为(2.30±0.82)头,2月龄断乳存活率为86.5%;而经产雌性西藏小型猪产仔数为(5.70±1.00)头,其2月龄断乳存活率为91.4%。哺乳期雌性西藏小型猪母性强,护仔行为强烈。结论广州地区西藏小型猪生长发育繁殖正常,产仔率和2月龄存活率等繁殖性能指标与原产地一致。     

北京地区食蟹猴的室内试验性繁殖初报

目的食蟹猴在北京地区的适应性驯养与繁殖。方法从2004年底开始,建立了一个20只雄猴,140只雌猴的食蟹猴室内生产繁殖种群。每个室内饲养单元内包括两只雄猴,14只雌猴,采取自由交配的方式进行繁殖。同时对室内饲养食蟹猴繁殖的季节性、妊娠期、月经周期、仔猴出生体重等进行了观察、记录和统计。结果从2005年4月到2008年3月的3年时间,母猴怀孕305例,流产59例,生产仔猴246只。平均妊娠率、产仔率分别为74.0%和59.7%。室内饲养食蟹猴的繁殖没有明显的季节性,平均月经周期为（28.5±3.3）d（n=30）,平均妊娠期为（167±12）d（n=30）,仔猴的平均出生体重为（350±120）g（n=30）。结论食蟹猴能够在温带地区的室内进行成功的驯养和繁殖。     

蓝狐发情期及妊娠期血清五种 生殖激素含量变化

为探究发情期及妊娠期雌性蓝狐(Alopex lagopus)生殖激素的变化规律,选取11只繁殖期雌性蓝狐,采用放射免疫法(RIA)测定血清中雌二醇(E2)、促黄体生成素(LH)、促卵泡素(FSH)、孕酮(P)以及催乳素(PRL)的含量。结果表明,促卵泡素和促黄体生成素在发情期及妊娠期血清中浓度一直处于较稳定水平,并呈波动式分泌,最大值分别为(2.18±0.69)U/L和(8.82±1.83)U/L,同种激素不同检测日期数据两两比较差异不显著(P> 0.05);雌二醇在发情期和妊娠期血清中浓度亦处于较稳定水平,最大值出现在发情第1天,为(27.73±23.19)ng/L,数据两两比较差异亦不显著(P> 0.05);孕酮在发情期维持较高水平,最大值在发情第3天,为(2.41±1.35)μg/L,之后在妊娠期持续下降,分娩当天达到最低点,为(0.13±0.14)μg/L,数据两两比较差异显著(P <0.05);催乳素在发情期先下降,最低值为(0.15±0.04)U/L,第3天开始升高,并在妊娠期保持较高水平,到分娩时维持最高(0.21±0.05)U/L,数据两两比较差异不显著(P> 0.05)。初步探索了5种激素含量在发情和妊娠期间的动态变化,为养殖蓝狐的生殖生理提供参考数据。     

典型草原三种蝗虫成虫期的食物消耗量及其利用的初步研究

为了进一步明确蝗虫类群在草原生态系统内的功能作用,在内蒙古锡林河流域典型草原益和乌拉山地区,依蝗虫发生季节的次序,先后研究了3种优势蝗虫(毛足棒角蝗、宽须蚁蝗、亚州小车蝗)成虫群体在自然变温条件下取食羊草的食物消耗量和利用能力问题。 本文首先提出了群体饲育时,蝗虫个体平均寿命的计算式: (?)=sum from n=i-1 to (?) i·N_i/N_t 式中,i=个体寿命的天数;N_i=寿命为i的个体数,N_t=蝗虫实验种群的个体总数。 据上式计算得出3种蝗虫个体平均寿命,毛足棒角蝗:雄性为38.2±2.8天、雌性为31.4±2.2天;宽须蚁蝗:雄性为40.9±2.3天、雌性为30.2±1.6天、亚洲小车蝗:雄性为52.6±0.7天、雌性为40.6±2.3天。 3种蝗虫在其成虫历期内,平均个体累积食量玩 (干重,克)为:毛足棒角蝗的雄性为0.607±0.059、雌性为0.643±0.084;宽须蚁蝗的雄性为0.303±0.022、雌性为0.340±0.037;亚洲小车蝗的雄性为1.414±0.180、雌性为2.933±0.186。在不同蝗种间,其平均个体累积食量的差异显著(P<0.01)。 3种蝗虫的雌性个体的近似消化力（A.D.）均显著高于同种的雌性个体（p<0.01）;季节发生早的蝗种之近似消化力相对高于较晚期发生的种类（毛足棒角蝗>宽须蚁蚁蝗>亚洲小车蝗）。对摄入食物的转换效率（E.C.I.,E.C.D.）,则同种内的雌性个体均显著高于雄性（p<0.01）;不同蝗种间,以个体最小、在中期发生的宽须蚁蝗对摄入食物的转换效率为最高。     

高原鼠兔种群敏殖生态的研究

1985-1988年,在青海湖黑马河地区以耳标法对高原鼠兔的繁殖生态进行了研究。在繁殖群体中主要是来自上年出生的第1、2胎的鼠兔（82.85%）,第3胎和老体占少数。成年雌鼠兔100%参加繁殖,通常年产3胎,有的年份可产4胎或5胎。产仔数1-8只（平均为4.52±0.12）,1只雌鼠兔终生可产2-29只。妊娠期为22.2±0.13天。洞内哺乳期为11.65±0.01天。有的年份当年出生的少数雌鼠兔到36.8±3.05日龄可达到性成熟并参加繁殖,生1-2胎,雄鼠兔性成熟较晚。     

内蒙古扎鲁特旗栗斑腹鹀的繁殖生态及子代性比

2012年和2013年两年的4至7月,在内蒙古通辽市扎鲁特旗对栗斑腹鹀（Emberiza jankowskii）的繁殖生态及子代性比进行了研究,发现栗斑腹鹀产首枚卵的时间为5月13日至6月12日,窝卵数平均为（5.1 ± 0.6）枚（4 ~ 6枚,n = 51）,孵卵期平均为（11.5 ± 0.7）d（10 ~ 12 d,n = 19）。其中,2012年总计30巢,成功出飞13巢,繁殖成功率为43.3%;2013年总计30巢,成功出飞15巢,繁殖成功率为50.0%。栗斑腹鹀子代总体性比（雄性︰雌性）为（1.38 ± 1.03）︰1（0.25︰1 ~ 4.00︰1,n = 12）,2012年和2013年的子代性比分别为（1.20 ± 1.08）︰1（1.50︰1 ~ 4.00︰1,n = 5）和（0.86 ± 0.65）︰1（0.25︰1 ~ 2.00︰1,n = 7）,年际间栗斑腹鹀子代性比差异均不显著,P值分别为0.62（2012年）、0.44（2013年）与0.72（2012和2013年）。本研究对该地区栗斑腹鹀子代性比及提高栗斑腹鹀繁殖成功率和稳定其性比的措施进行了初步讨论。     

Serum levels of gonadotropins and gonadal steroids,including testosterone,during the menstrual cycle of the chimpanzee (Pan troglodytes)

The objective of this study was to expand the data on menstrual cycle serum hormone patterns in female common chimpanzees, both in terms of the number of cycles analyzed and by the addition of data on testosterone levels. Samples were obtained from 11 unanesthetized animals trained for conscious blood withdrawal. LH, FSH, 17β-estradiol (E₂), progesterone (P), and testosterone (T) were measured by radioimmunoassay, genital swelling was recorded, and menstrual blood was noted. Concurrent midcycle elevations in LH and FSH and luteal phase elevations in progesterone suggested that the cycles were ovulatory. Detumescence of genital swelling occurred about 3 days after the midcycle LH peak, 1 day after the luteal phase nadir in E₂, and 1 day after P levels exceeded 5 ng/ml. These relationships provide further support for the use of genital swelling in monitoring progress of the menstrual cycle. The hormone patterns in the chimpanzees closely resembled those of the human females, but E₂ and T levels were higher. The levels of E₂ and T were higher and the midcycle elevation in T was broader in the chimpanzee than in gorillas and orangutans. This is of interest because E₂ and T are implicated in the regulation of mating, and chimpanzees mate over a greater portion of the cycle than the other apes. These data indicate the need for further study of hormonal contributions to the different patterns of mating in the great apes. They also support the use of the female common chimpanzee as a model for the human female in endocrine studies of the menstrual cycle.     

Growth and reproductive parameters of bonnet monkey (Macaca radiata)

The present paper summarizes some of the important biological and physiological data recorded over a 30-year period on the biology of bonnet monkeys in captivity. Data on sexual maturity, menstrual cyclicity, general behaviour, endocrine profile, reproductive physiology, gestation, parturition, postpartum amenorrhoea in the female, and sexual maturity, hormone profile, and seasonal variation in sperm count of the male monkeys are presented. In addition to the biological values, weights of selected organs, vertebral and dental pattern are also presented. Menarche occurred at an age of 36±4 months and the first conception in the colony occurred at an age of 54±4 months. The average menstrual cycle length was 28±4.3 days. Majority of monkeys did not cycle regularly during March–June during which the temperature reached a peak. The pregnancy index of the colony was 80% with controlled breeding. The gestation period was 166±5 days with 6–7 months postpartum amenorrhoea. Males attained sexual maturity by the age of 6–7 years and exhibited the characteristic nocturnal surge of serum testosterone at this age and sperm concentration ranged from 116–799 millions/ejaculate.     

The effects of aging on hormone and reproductive cycles in female chimpanzees (Pan troglodytes)

In contrast to those for human females, observational cycle data available for chimpanzees suggest that menstrual cycling, and thus reproductive potential, continues until near death. This study documents age-related changes in estrous cycling and hormone profiles in 14 female chimpanzees (Pan troglodytes) ranging in age from 31 to 50 y. Estrous data were analyzed from daily cycle charts, averaging 13.3 y of cycle data per subject, after omission of gestational and postpartum amenorrhea. Concentrations of total luteinizing hormone (LH), follicle-stimulating hormone (FSH), estradiol (E2), and other hormones were assayed in serum samples taken biannually. Sample collection times were chosen to avoid the ovulatory LH and FSH peaks of the female's cycle and yielded a mean of 19.6 serum samples over an average of 14.4 y per subject. Analysis of cycle charts revealed a negative relationship between age and the percentage of cycle days at maximal tumescence. There also were positive relationships between age and the length of the estrous cycle and age and the percentage of cycle days at complete detumescence. Analysis of hormonal data revealed curvilinear relationships between age and both LH and FSH. These cycle and hormonal changes mirror those in perimenopausal and menopausal women. Our data provide evidence of perimenopause (at 30 to 35 y) and menopause (at 35 to 40 y) in the chimpanzee.     

Chimpanzee genital swelling and its role in the pattern of sociosexual behavior

Behavioral observations were made on thirteen female and seven male adult group-living chimpanzees (Pan troglodytes). The behavioral data were analyzed as a function of the day of the females' menstrual cycles to explore the possible interrelationship between genital swelling and sociosexual behavior of female chimpanzees. Copulatory behavior was confined almost entirely to the period of genital swelling and the occurrence of male-to-female genital inspection (both female- and male-initiated) was negatively correlated with the days from swelling onset, i.e., as the presumed day of ovulation approached, genital inspection decreased, while copulatory behavior increased. In addition, more females groomed their male cagemates during the luteal phase than in the follicular phase of their cycles, whereas male-to-female grooming was positively correlated with the progress of the cycle, with peaks during the time of swelling onset and menstruation. The profile of sociosexual behavior observed throughout the menstrual cycle suggested that, although chimpanzees exhibit an extended period of sexual receptivity and genital swelling, the presumed fertile period is not concealed. The role of genital swelling in chimpanzees is discussed in relation to the possible hormonal effect on female sexuality and the evolution of chimpanzee mating strategies. © 1992 Wiley-Liss, Inc.     

Disturbance of the Duration in the Menstrual Cycle under the Influence of Tight Clothing

We investigated the influence of skin pressure by clothing on the duration of menstrual cycle with 33 young adult women. The average age was 19.9 ± 2.1 years (mean ± SD), stature 159.5 ± 5.6cm and body mass 50.9 ± 5.5kg. Thirty-three women participated as subjects. They wore their usual clothing including foundation garments, panty stocking, pants or skirt and T-shirt or blouse and cardigan for the first 4 months from December to March (‘Tight 1’). For the second 4 months from April to July, the women wore loose clothes, i.e., they did not wear foundation garments at home. Skirt and jeans were worn loosely (‘Loose’). For the last 4 months, from August to November, they wore their clothes as tightly as possible, compared to ‘Tight 1’ (‘Tight 2’). Each participant marked the first day of the occurrence of menses in the pocket diary throughout the year. The main results were summarized as follows: 1) The average duration of the menstrual cycle was 44.2 ± 14.9 days (mean ±) in ‘Tight 1’, 30.4 ± 3.0 days in ‘Loose’ and 47.4 ± 22.7 days in ‘Tight 2’. 2) The number of months when the menses did not occur was 38 for ‘Tight 1’, 6 for ‘Loose’ and 40 for ‘Tight 2’. 3). The number of participants who had a duration of the menstrual cycles for more than 40 days, was 25 participants for ‘Tight’, 10 for ‘Loose’ and 29 for ‘Tight’. It can be concluded that skin pressure by clothing could disturb the duration in the menstrual cycle.     

Temporal and endocrine sequelae of aspirating follicular contents in rhesus monkeys

Aspiration of ovarian follicular contents in humans is a well-established procedure used to obtain oocytes for fertilization in vitro (IVF). However, the effects of aspiration on the menstrual cycle and resulting luteal function have been incompletely characterized. The present study was designed to investigate alterations in the temporal and endocrine characteristics of menstrual cycles following aspiration of contents of the dominant preovulatory follicle (DF) on day 10 of the cycle in normal rhesus monkeys. When aspiration was performed prior to the preovulatory surge of luteinizing hormone (LH), cycle length was extended to 38.6 ± 8.6 [15] (x days ± SD, [n]), as compared to 29.5 ± 5.7 [8] days when the surge occurred before the time of aspiration. Mean and maximal amounts of progesterone (P) in the luteal phase and the number of days in which P-values were > 1 ng/ml were significantly greater when aspiration was performed prior to the surge of LH than for aspiration after this event. Laparoscopic observations made in the midluteal phase in animals of the former group demonstrated that the corpus luteum (CL was derived from a follicle other than the original DF which had been aspirated on day 10 of the menstrual cycle; observations in the latter group of animals indicated that the CL was derived from the DF.     

Dynamics of circulating concentrations of gonadotropins and ovarian hormones throughout the menstrual cycle in the bonnet monkey: role of inhibin A in the regulation of follicle‐stimulating hormone secretion

In higher primates, increased circulating follicle‐stimulating hormone (FSH) levels seen during late menstrual cycle and during menstruation has been suggested to be necessary for initiation of follicular growth, recruitment of follicles and eventually culminating in ovulation of a single follicle. With a view to establish the dynamics of circulating FSH secretion with that of inhibin A (INH A) and progesterone (P₄) secretions during the menstrual cycle, blood was collected daily from bonnet monkeys beginning day 1 of the menstrual cycle up to 35 days. Serum INH A levels were low during early follicular phase, increased significantly coinciding with the mid cycle luteinizing hormone (LH) surge to reach maximal levels during the mid luteal phase before declining at the late luteal phase, essentially paralleling the pattern of P₄ secretion seen throughout the luteal phase. Circulating FSH levels were low during early and mid luteal phases, but progressively increased during the late luteal phase and remained high for few days after the onset of menses. In another experiment, lutectomy performed during the mid luteal phase resulted in significant decrease in INH A concentration within 2 hr (58.3±2 vs. 27.3±3 pg/mL), and a 2‐ to 3‐fold rise in circulating FSH levels by 24 hr (0.20±0.02 vs. 0.53±0.14 ng/mL) that remained high until 48 hr postlutectomy. Systemic administration of Cetrorelix (150 µg/kg body weight), a gonadotropin releasing hormone receptor antagonist, at mid luteal phase in monkeys led to suppression of serum INH A and P₄ concentrations 24 hr post treatment, but circulating FSH levels did not change. Administration of exogenous LH, but not FSH, significantly increased INH A concentration. The results taken together suggest a tight coupling between LH and INH A secretion and that INH A is largely responsible for maintenance of low FSH concentration seen during the luteal phase. Am. J. Primatol. 71:817–824, 2009. © 2009 Wiley‐Liss, Inc.     

In. vitro evaluation of corpus luteum function of cycling and pregnant rhesus monkeys: Progesterone production by dispersed luteal cells

Corpus luteum function in the cycling and the pregnant rhesus monkey (Macaca mulatta) was evaluated through short term $\text{in vitro}$ studies of progesterone production by suspensions of collagenase-dispersed luteal cells in the presence and absence of exogenous gonadotropin (human chortonic gonadotropin, HCG). Cells from mid-luteal phase of the menstrual cycle secreted progesterone, as measured by accumulation of this hormone in the incubation medium, and responded to the addition of 100 ng HCG/ml with a marked increase in progesterone secretion above basal level ($\text{63.7 ± 13.1}\text{versus}\text{24.7 ± 5.5}\text{ng progesterone}\text{/}\text{ml}\text{/5 × 10}{}^4\text{cells}\text{/ 3}\text{hr}\text{,}\text{X}\text{± S.E.,}\text{n}\text{= 6;}\text{p}\text{< 0.05}$). However, luteal cells from early pregnancy (23–26 days after fertilization) secreted significantly less progesterone than cells of the non-fertile menstrual cycle (3.6 ± 2.4 versus 24.7 ± 5.5 ng/ml/5 × 10⁴ cells/3 hr, n = 3; p < 0.05) and did not respond to HCG with enhanced secretion. By mid-pregnancy (108–118 days gestation) luteal cells exhibited partially renewed function, and near the time of parturition (163–166 days gestation) basal and HCG-stimulated progesterone secretion (30.2 ± 5.6 and 63.0 ± 13.0 ng/ml/5 × 10⁴ cells/3 hr, respectively; n = 3) was equivalent to that of cells from the luteal phase of the non-fertile menstrual cycle. The data suggest that following a period around the fourth week of gestation, when steroidogenic activity is markedly diminished, the corpus luteum of pregnancy progressively reacquires its functional capacity and at term exhibits gonadotropin-sensitive steroidogenesis similar to that of the corpus luteum of the menstrual cycle.     

Transcervical endometrial biopsy in the baboon: Effects on the menstrual cycle and relations to protein and dry matter content and histology

The baboon has been used increasingly for reproductive studies. While hormonal regulation of the menstrual cycle and ovulation as well as the endocrinology of gestation have been reported, little information is available describing endometrial parameters. It is the purpose of this paper to describe the ease with which repeated transcervical biopsies can be performed, to describe baseline endometrial protein and dry weight data and to demonstrate that the biopsy procedure itself does not significantly affect the baboons' ability to continue normal menstrual cycle function. Endometrial biopsy samples were taken throughout the menstrual cycle under light ketamine anesthesia. Protein and dry weight contents were determined. Endometrial biopsies Protein and dry weight contents were determined. Endometrial biopsies averaged 25 mg (wet weight) and contained 7.54% protein and 16.3% dry matter. The formulas (Y = a + bx) which expressed the linear relationships between wet weight (mg), protein (μg) and dry matter (μg) content and the correlation coefficients (r) were as follows: between wet weight and protein content – wet weight = 5.58 + 10.0 (protein), Sxy = 4.83, r = 0.883; between wet weight and dry weight – wet weight = 1.99 + 7.94 (dry weight), Sxy = 4.52, r = 0.904; between protein and dry weight – protein = 0.446 + 0.446 (dry weight), Sxy = 4.82, r = 0.870. All three linear regression coefficients were statistically significant (P < 0.001). No significant cyclical patterns in either protein or dry matter content were demonstrable throughout the menstrual cycles. The average length of all nonbiopsy cycles was 32.4 ± 2.7 days and 32.8 ± 3.6 days for those in which biopsies were taken. Similarly, follicular and luteal phase lengths for nonbiopsy and biopsy cycles were 15.4 ± 2.3 and 15.5 ± 2.8 days and 16.9 ± 2.2 and 17.2 ± 3.2 days, respectively. The time required for sex-skin swelling to decrease from maximum to minimum during the luteal phase was shorter, but the quiescent stage was equally lengthened. It was concluded that the endometrium of the baboon was easily accessible for study without causing serious alterations in menstrual cycle function. These studies further demonstrate the potential of the baboon as a model o reproductive studies. In fact, the baboon may well the only practical primate model available for endometrial studies.     

Menstrual cycles in rhesus monkeys (Macaca mulatta) are unaffected by a single dose of the anesthetics ketamine and xylazine administered during the midfollicular phase at laparoscopy

To identify an anesthetic regimen that produces more complete relaxation and analgesia than ketamine hydrochloride (Ketaset®) alone, a combination of ketamine (15 mg/kg body weight) and the hypnotic xylazine (Rompun®, 0.33 mg/kg) was evaluated. Since the desired experimental application required that the anesthetic not interfere with normal hormonal events during the menstrual cycle, this combination administered on day 6 of the cycle was tested to determine whether hormonal surges, incidence of ovulation, or cycle length would be altered relative to the use of ketamine alone. In five of six animals, ketamine plus xylazine had no effect on the occurrence of timely surges of estrogen, luteinizing hormone (LH), or follicle-stimulating hormone (FSH), or on ovulation as determined by the presence of a corpus luteum at laparoscopy and normal serum concentrations of progesterone. There were no significant differences between the cycle during treatment and previous cycles in the same animal for length of the menstrual cycle (26.0 ± 2.3 [5] days; X? ± S.D. [n] or luteal phase (13.4 ± 2.4 [5] days). Likewise, these values did not differ from those of ten control monkeys treated with ketumine only on day 5 or 6 of the cycle (incidence of ovulation, 10/10; cycle length, 27.9 ± 1.8 [10]; luteal phase length, 15.1 ± 1.4 [10], P > 0.05). Patterns of circulating progesterone were not altered by the addition of xylazine anesthesia. These findings indicate that xylazine, given in the midfollicular phase, did not alter ovulatory events or menstrual cycle characteristics in rhesus monkeys. Ketamine plus xylazine apparently provides anesthesia appropriate for laparoscopy.