Comparison of histoenzymological alterations in the contralateral ovary of nulliparous and parous females of the bat Taphozous melanopogon melanopogon Temmnick (Microchiroptera, Mammalia) displaying absolute dextral dominance of the genital tract

Taphozous melanopogon melanopogon is a unique emballonurid microchiropteran which exhibits a 100% dextral dominance of the female genital tract. Folliculogenesis occurs in the contralateral ovaries, but it is only in the right ovary that a single Graafian follicle attains maturity and ovulates. The product of fertilization is implanted in the dextral uterine cornu. Seven types of follicles were identified in the right ovary, as compared with five in the left, on the basis of shape, size and number of associated granulosa cells. In the parous bats, a single, nearly extroverted corpus luteum was discerned in the ovary which survived for 2-2 1/2 months. The left ovary was nearly a vestigial structure during pregnancy. The structural asymmetry of the internal genitalia was observed to be correlated with the histochemical site and pattern of distribution of acid phosphatase and alkaline phosphatase. Differential activities of phosphatases were discerned in the developing primary, secondary, preantral and antral follicles and the interstitial tissues of the contralateral ovary during the nulliparous state. A high enzyme reaction was displayed by follicles undergoing atretic and degenerative changes. In the parous bats, pronounced differences were noted in the histologic constituents of the contralateral ovary. This study shows a significant link between functional asymmetry of the genitalia and the structural and enzymological characteristics of the ovarian tissues.     

Ultrasonographic study of the effects of the corpus luteum on antral follicular development in unilaterally ovulating western white-faced ewes

The objective of this study was to examine the local effects of the corpus luteum (CL) on ovarian antral follicle development by looking at follicle populations and dynamics in ovaries with or without CL, in unilaterally ovulating ewes, using a retrospective analysis of daily ultrasonographic records. The present report summarises the data from the first luteal phase of the breeding season (August-October; n = 4), a luteal phase in the mid-breeding season (November-December; n = 5), the last luteal phase of the breeding season (January-March; n = 5), and the luteal phase after GnRH-induced ovulations in mid-anoestrus (May-June; n = 4) of western white-faced ewes. Mean daily numbers of 3mm follicles that did not grow any larger were significantly reduced in the CL-containing ovaries of ewes at all periods of study except for the transition to anoestrus. With all scanning periods combined, daily numbers of 3mm follicles not growing further increased (P<0.05) between day 6 and 15 after ovulation in the CL-containing ovaries. Based on mean data for the whole periods of observation, the non-CL-bearing ovaries of ewes in the transition to anoestrus had fewer (P<0.05) follicles growing from 3 to > or =5mm in size before regression compared with the mid-breeding season and mid-anoestrus. The lifespan of follicles reaching > or =5mm in diameter was shorter (P < 0.05) in the CL- compared with non-CL-containing ovaries of anoestrous ewes induced to ovulate with GnRH ((6.5+/- 1.3) and (9.0+/- 1.0) days, respectively). Circulating concentrations of progesterone were lower during both transitional periods (into and out of anoestrus) and mid-anoestrus than during the mid-breeding season (P < 0.001), and were less during anoestrus than during both transitional periods (P < 0.05). It was concluded that CL/luteal structures locally suppressed the growth of ovarian antral follicles to the 3mm size-range except during the transition to anoestrus, but that there was no inhibitory effect of the CL on the growth of ovarian follicles to larger diameters. The presence of CL/luteal structures did not affect the length of the lifespan of follicles reaching > or =5mm in diameter nor the number of ovulations per ovary in cyclic ewes, but shortened large follicle lifespan in anoestrous ewes. Variations in peripheral concentrations of progesterone across the breeding season and between the breeding season and anoestrus did not alter the lifespan of large antral follicles. In the transition to anoestrus and during mid-anoestrus, the presence of the CL in an ovary appeared to maintain follicle development to ovulatory sizes and to increase the rate of turnover of large antral follicles, respectively.     

Immunocytochemical studies of relaxin in ovaries of pregnant and cycling mice

Immunocytochemical staining for relaxin in ovarian sections of pregnant mice from day 11 through day 18 of gestation revealed that only corpora lutea (CL) of pregnancy are stained. Evaluation of serial sections of ovaries from a day 16 pregnant mouse revealed that the only luteal structures present are CL of pregnancy. The number of CL present in each ovary equaled the number of implantation sites in each related horn (7 on the right side and 8 on the left side). These large CL varied in shape, being round in some profiles to very elongate in others. All CL were immunochemically stained for relaxin using the peroxidase-antiperoxidase method of L. Sternberger (Immunocytochemistry, 2nd ed. Wiley, New York, 1979). The intensity of the strain varied from cell to cell within each CL. Small luteal structures that were observed to be immunochemically stained for relaxin were demonstrated to represent the periphery of CL of pregnancy. No luteinized follicles were observed and interstitial cells and follicles were not immunochemically stained in any of the day 16 serial ovarian sections or in any of the ovarian sections from pregnant mice on the other days of gestation studied. CL of previous cycles were not observed to be present in the ovaries at days 15, 16, or 18 of gestation. However on day 14 and before, CL of previous cycles were observed and they did not exhibit any relaxin immunostaining. Immunocytochemical studies using the biotin-avidin system revealed that no relaxin immunostaining could be demonstrated in the ovaries of cycling mice at any stage of the estrous cycle. In conclusion, this study revealed that the only ovarian structures demonstrating relaxin immunocytochemical staining in the mouse were CL of pregnancy.     

Functional anatomy of the female genital organs of the wild black agouti (Dasyprocta fuliginosa) female in the Peruvian Amazon

This study examined anatomical and histological characteristics of genital organs of 38 black agouti females in the wild in different reproductive stages, collected by rural hunters in the North-eastern Peruvian Amazon. Females in the follicular phase of the estrous cycle had greater antral follicle sizes than other females, the largest antral follicle measuring 2.34mm. Antral follicles in pregnant females and females in luteal phase of the estrous cycle had an average maximum diameter smaller than 1mm. In black agouti females in follicular phase, some antral follicles are selected to continue to growth, reaching a pre-ovulatory diameter of 2mm. Mean ovulation rate was 2.5 follicles and litter size was 2.1 embryos or fetuses per pregnant female, resulting in a rate of ovum mortality of 20.8%. Many follicles from which ovulation did not occur of 1-mm maximum diameter luteinize forming accessory CL. The constituent active luteal tissues of the ovary are functional and accessory CL. Although all females had accessory CL, transformation of follicles into accessory CL occurred especially in pregnant females, resulting in a contribution from 9% to 23% of the total luteal volume as pregnancy advances. The persistence of functional CL throughout pregnancy might reflect the importance for the maintenance of gestation and may be essential for the continuous hormonal production. The duplex uterus of the agouti female is composed by two completely independent uterine horns with correspondent separate cervices opening into the vagina. In pregnant females, most remarkable observed uterine adaptations were induced by the progressive enlargement caused by the normal pregnancy evolution. The wild black agouti showed different vaginal epithelium features in accordance with the reproductive state of the female.     

Immunocytochemical localization of aromatase in immature rat ovaries treated with PMSG and hCG,and in pregnant rat ovaries

Summary Immunocytochemical localization of aromatase cytochrome P-450 was examined in immature rat ovaries treated with pregnant mare serum gonadotropin (PMSG) and human chorionic gonadotropin (hCG), and in pregnant rat ovaries. It is well known that PMSG and hCG treatments induce ovulation about 12 h after hCG injection.At 24 h after hCG injection, many antral follicles were recognized in immature rat ovaries and only the granulosa cells in the antral follicles were stained weakly with the anti-aromatase antibody. At 0 to 9 h after hCG injection, in addition to the antral follicles, some large Graafian follicles could be observed in the rat ovaries, and the granulosa cells of these follicles were positively stained for aromatase. Each follicle was surrounded by the basal lamina which shows lineally distinct positive reaction against anti-laminin antibody. At 12 h after hCG injection, some large Graafian follicles without oocyte were weakly positive to the anti-aromatase antisera, and the outline of their basal lamina stained with anti-laminin antibody became irregular in shape and fragmentous. At 15 to 18 h after hCG injection, the luteinized cysts could be seen, and the granulosa-lutein cells of these cysts were almost negative for aromatase. Fragmentous reaction to the anti-laminin antibody was observed around the luteinized cysts.In the ovaries of day 4 in pregnancy, only the granulosa cells of the large antral follicles were weakly stained, but corpora lutea negatively reacted to the anti-aromatase antibody. At 7 to 19 days in gestation, both the granulosa cells of antral follicles and pregnant luteal cells were positively stained against aromatase antisera. The luteal cells were increased in size during pregnancy. And weakly positive reaction was detected on day 7 of pregnancy, then the immunoreaction became stronger in the corpora lutea on day 15 and 19 of pregnancy.The localization of aromatase was immunocytochemically examined in immature rat ovaries treated with PMSG and hCG injection, and the reaction of the granulosa cells of the antral follicles against anti-aromatase antibody became strongly positive about 12 h before ovulation and the became very weak suddenly after ovulation. In rat-ovaries, the pregnant corpora lutea was positively stained for aromatase after day 7 of pregnancy.This study was supported by Grants from the Ministry of Education, Science and Culture, Japan, and from USPHS Research Grants HD04945, USA     

Ultrasonographic study of ovarian function during early pregnancy and after parturition in the ewe

Transrectal ultrasonography of ovaries was performed in 11 ewes from Days 10 to 26 and on Day 30 of pregnancy to record the number, size, and position of ovarian follicles > or = 3 mm in diameter and corpora lutea (CL). Transrectal and/or transabdominal ultrasonography of the uterus was performed on Days 10 to 26, 30, 35, 40, 45 and 50 of gestation to ascertain the number and position of the conceptuses. In a second experiment, ultrasonography was conducted in 15 ewes on Days 10, 25, 30, 45 and 50 of pregnancy and from Days 13 to 29 after parturition. Ovarian data were classified into ovaries without CL (Group 1), ovaries with the CL in 1 ovary (Group 2), and ovaries with the CL in both ovaries during pregnancy (Group 3). In early pregnant ewes, the total number of follicles and the diameter of all follicles > or = 3 mm were smaller (P < 0.05) in the CL-bearing ovaries (both Group 2, n = 7 and Group 3, n = 8) than in the non-CL-bearing ovaries (Group 1, n = 7), while the largest follicle diameter was significantly smaller in Group 3 than in Group 1 or 2 ovaries. The number of 3-mm follicles in Group 2 ovaries was lower (P < 0.05) than in Group 1 or 3 ovaries, but the mean number of follicles > or = 5 mm in diameter was significantly lower in Group 3 than in Group 1. The total luteal volume per ovary was higher (P < 0.001) in Group 2 than in Group 3 ovaries of early pregnant ewes. The total follicle diameter and the number of follicles growing from 3 to > or = 5 mm in diameter was lower (P < 0.05) for Group 2 ovaries of ewes that carried twins (n = 3) compared with Group 2 ovaries from ewes with singletons (n = 4). There were no differences in follicular dynamics between Group 3 ovaries and the ovaries of Group 2 in ewes that carried twins. No follicles > 3 mm were seen in the ovaries of postpartum ewes that contained CL during gestation, until Days 21 and 25 postpartum for Groups 2 (n = 10) and 3 (n = 8), respectively, and follicles reaching > or = 5 mm in diameter were detected in only 2 ovaries (Group 2), on Days 27 and 28 postpartum, respectively. We conclude that during early pregnancy in ewes there is a suppression of antral follicle growth which appears to be exerted primarily by the developing conceptus but remains confined to CL-bearing ovaries. Residual local inhibition of follicular development extends into the postpartum period.     

Corpus luteum function following single and double ovulation during estrous cycle in Sanjabi ewes

This study compared the effect of double and single ovulation on serum progesterone concentrations and luteal characteristics in Sanjabi ewes at different days of the estrous cycle. The estrous cycles of 197 Sanjabi ewes were synchronized by a 12-day treatment with intravaginal sponges (Chronogest^®). Estrus was detected in 144 ewes 27–39 h after sponge removal. Daily blood samples were taken every morning and analyzed for serum progesterone (P4). Ewes were then transported to a local abattoir, where nine ewes were slaughtered on each experimental day (days 1–16 after estrus) for ovary collection. The ovarian follicles were measured and categorized by size (very small <2 mm; small 2–3.5 mm; medium 3.5–5 mm; large >5 mm). On each slaughter day, the number of corpora lutea per ewe was classified as single and double ovulation. The results show that the effect of dominant follicles was less during the mid-luteal phase. Ovulation rate of right, left and both ovaries were (54.9%), (23.6%) and (21.5%), respectively. The incidence of double ovulations was 40.2%. In the case of ewes exhibiting double ovulation, 46.6% occurred unilateral (ewes exhibited both ovulations on the right ovary); whereas 53.4% occurred bilateral (ewes exhibited ovulations on the right and left ovaries). Unilateral double ovulation was not observed in the left ovary. The right ovary appeared to play a significantly greater role in ewes showing single and double ovulations than the left ovary (P < 0.05). Serum progesterone concentration showed minimum and maximum levels of 0.29 ± 0.15 and 5.51 ± 0.75 ng/ml on days 16 and 11 post-estrous, respectively (P < 0.001). The mean volume of individual corpus lutea in ewes with single ovulations was significantly higher than in ewes with double ovulations (P < 0.01). However, the total volume of corpus lutea in ewes with single ovulation was significantly lower than in ewes with double ovulations in some days of estrous cycle (P < 0.01). The serum progesterone concentration was significantly higher in double than single ovulating animals on days 1–16 of the estrous cycle (P < 0.001). These results indicated a relatively high incidence of double ovulation in ewes associated with increasing total luteal volume and high circulating concentrations of progesterone.     

Histochemical study of superoxide dismutase in the ovary of the rat during the oestrous cycle

Superoxide dismutase, an enzyme which causes the dismutation of superoxide free radical anions to generate hydrogen peroxide, has been localized in the rat ovary. The negative-staining method was used to provide photo-induced reduction of nitro-blue tetrazolium in cryostat sections of rat ovaries for histochemical localization of superoxide dismutase. Superoxide dismutase was found in growing follicles, the membrane granulosa of Graafian follicles, ovulated follicles and blood vessels. It is suggested that superoxide dismutase may play a role in regulating follicular development, ovulation and luteal functions.     

Effect on oestrus and ovulation of exposing creole goats to the male at three times of the year

The characteristics of the oestrous and ovarian cycles of local goats were studied over 2 years, on 96 females in March, 60 in July and 100 in November. After 3 weeks of separation between sexes, the females with inactive ovaries were identified and harnessed males were introduced. Detection of oestrus was undertaken daily and the date and rate of ovulation were checked at laparoscopies. The proportion of females with non-cyclic ovaries before the mating period varied according to the season and whether the females were nulliparous or suckling. Among the females with inactive ovaries before the mating period, 97% ovulated 2 . 8 days after the introduction of males; 68% of these initial ovulations were accompanied by oestrus and 76% resulted in short luteal phases (5 . 3 days) followed by a second ovulation accompanied by oestrus 89% of the time. The proportions of initial ovulations with oestrus and of initial ovulations followed by a short luteal phase were in linear relationship with the proportion of females with non-cyclic ovaries before the mating period. For the females with cyclic ovaries before the mating period, the distribution of first oestrus during the 8 days after the introduction of males was significantly different from the expected uniform distribution. A possible luteolytic action of teasing was suspected. The fertility of females in all groups was high (greater than 79%). Litter size was not different for non-cyclic and for cyclic females.     

The inter-ovarian distribution of dominant follicles is influenced by the location of the corpus luteum of pregnancy.

The objective was to characterise the distribution of dominant ovarian follicles in the early post-partum period in relation to the side of the preceding pregnancy and its relationship with the left and right ovaries. Primiparous cows were enrolled over a 2-year period (n = 33 in Year 1 and n = 28 in Year 2). Ovarian follicles were observed daily by trans-rectal ultrasonography commencing within 9 days of calving. Dominant follicles (DF) were described as occurring on the ovary ipsilateral to the CL of preceding pregnancy (ipsilateral ovary of pregnancy, IOP) or contralateral to the CL of the preceding pregnancy (contralateral ovary of pregnancy, COP), and as occurring on the left or right ovary. Results in Year 1 were analysed for the effect of breed (Friesian n = 15; Jersey n = 18). There was a bias towards the COP for the first DF post-partum in both breeds (DF1; 70%; p<0.05). A breed interaction was observed with the second DF post-partum with a bias towards the COP in the Friesian (93%; p<0.05); but not the Jersey animals (50%). In Year 2, all cows were Friesians, and there was again a biased distribution of the DF1 towards the COP (89%; p<0.05) and for the combined distribution of the first three DF post-partum (76%; p<0.05) as well as the first ovulatory follicle (71%; p<0.05). A comparison of the pooled data for the location of the DF1 from both years showed that only one DF1 was observed on a left ovary in the 29 cases where the preceding pregnancy was also on the left side. This study demonstrated a bias in the distribution of DL in the early post-partum period towards the ovary on the side opposite that of the preceding pregnancy as well as towards the right side.     

Morphological changes of the ovary and hormonal changes through the ovarian cycle of the common marmoset (Callithrix jacchus)

Laparoscopic observations of morphological changes of the ovary during the ovarian cycle in conjunction with radioimmunoassay of serum progesterone and estradiol-17β was investigated as a method of monitoring the ovarian cycle in the common marmoset. In the common marmoset, plural follicles first appeared in each ovary five days prior to ovulation. At three to four days prior to ovulation one or two follicles developed into translucent blisters on the surface of the ovary. As the follicles filled with follicular fluid, they became larger and clearer until one to two days prior to ovulation, at which time they formed well defined, transparent bubbles protruding from the surface of the ovary. After ovulation, the ovulation point could be detected at the center of the follicle, sometimes surrounded by a corpus of engorged blood vessels. Ovulations of the plural follicles were not simultaneous, and due to the time lag ovulations took at least 12 to 20 hrs in four out of seven animals examined. After two to five days of ovulation the corpus hemorragicum, a bright red protrusion made of tissue and blood disrupted by ovulation, was found. Subsequently, the color of the formatted corpus luteum changed from dark-red to yellow then to yellow white. While the corpus luteum remained reddish in color serum progesterone was maintained at as high levels as in the luteal phase. There was no mature follicle or corpus luteum in subordinate female ovaries.     

Complex interrelationships among CL,preovulatory follicle,number of follicular waves,and right or left ovaries in heifers

The diameter of the dominant follicle (DF) of wave 1 was studied on Days 9 to 17 (Day 0 = ovulation) in a survey of the ipsilateral and contralateral relationships between the location of the DF and CL, and number of follicular waves per interovulatory interval (IOI). For contralateral relationships, regardless of number of waves the diameter of the DF of wave 1 decreased (P < 0.03) between Days 11 and 13 when referenced to the follicle–CL relationship of wave 1 and decreased (P < 0.008) between Days 9 and 11 when referenced to the preovulatory follicle (PF)–CL relationship. For wave 2 in two-wave IOIs, the CL ovary of ipsilateral relationships had more (P < 0.05) follicles that reached at least 6 mm than the non-CL ovary. In three-wave IOIs, frequency of IOIs with the DF in the CL ovary was greater (P < 0.02) for wave 2 than for wave 3. In wave 3, the preovulatory and the largest subordinate follicles were located more frequently (P < 0.005) in the contralateral ovary. Ovulation in two-wave IOIs occurred more frequently (P < 0.0009) from the right ovary. In three-wave IOIs with a contralateral relationship ovulation occurred more frequently (P < 0.003) from the left ovary; a negative intraovarian effect of the CL on location of the PF may account for more ovulations from the left ovary and a reported greater frequency of the contralateral relationship. The hypothesis was supported that the ipsilateral versus contralateral relationship between the PF and CL is affected by the DF–CL relationship during the previous follicular waves and by the number and identity of waves per IOI.     

Ovarian folliculogenesis in collared peccary, Pecari tajacu (Artiodactyla: Tayassuidae)

The sustainability and production of collared peccary (Pecari tajacu) has been studied in the last few years; however, further information on its reproduction is necessary for breeding systems success. Understanding folliculogenesis aspects will contribute to effective reproductive biotechniques, which are useful in the preservation and production of wildlife. The aim of this study was-to evaluate the ovarian folliculogenesis in collared peccary. Ovaries from six adult females of collared peccary were obtained through ovariectomy and analyzed. These were fixed in aqueous Bouin's solution and sectioned into 7 microm slices, stained with hematoxilin-eosin and analyzed by light microscopy. The number of pre-antral and antral follicles per ovary was estimated using the Fractionator Method. The follicles, oocytes and oocyte nuclei were measured using an ocular micrometer. Results showed that the length, width, thickness, weight, and the gross anatomy of the right and left ovaries were not significantly different. However, the mean number of corpora lutea was different between the phases of the estrous cycle (p<0.05), with the highest mean in the luteal phase. Primordial follicles were found in the cortex; the oocytes were enveloped by a single layer of flattened follicular cells. In the primary follicles, proliferation of the follicular cells gave rise to cuboidal cells (granulosa cells). The secondary follicle was characterized by two or more concentric layers of cuboidal cells (granulosa), beginning of antrum formation, and the presence of pellucid zone and theca cells. Antral follicles were characterized by a central cavity (antrum), the presence of cumulus oophorus and theca layers (interna and externa). In the right ovary, the values of the primordial and primary follicles were similar, but significantly different from the secondary ones (p<0.05). In the left ovary, significant differences were observed between all follicles in the follicular phase (p<0.05); the mean number of primordial and primary follicles was similar in the luteal phase. The mean number of pre-antral follicles and antral follicles in the follicular phase was higher in the left ovary (p<0.05). The mean number of antral follicles in the luteal phase was similar in both ovaries. We also found significant differences in mean diameter of preantral follicles, oocyte, granulosa layer and oocyte nucleus during the estrous cycle. In the antral follicles a significant difference was observed only in follicular diameter (p<0.05). The predominance of active primordial and primary follicles was found in both phases; otherwise the secondary follicles and antral follicles showed a high degree of degeneration. The results obtained in the present work will strengthen the development of biotechnology programs to improve the productive potential and conservation of the collared peccary.     

Immunocytochemical localization of aromatase in immature rat ovaries treated with PMSG and hCG, and in pregnant rat ovaries

Immunocytochemical localization of aromatase cytochrome P-450 was examined in immature rat ovaries treated with pregnant mare serum gonadotropin (PMSG) and human chorionic gonadotropin (hCG), and in pregnant rat ovaries. It is well known that PMSG and hCG treatments induce ovulation about 12 h after hCG injection. At 24 h after hCG injection, many antral follicles were recognized in immature rat ovaries and only the granulosa cells in the antral follicles were stained weakly with the anti-aromatase antibody. At 0 to 9 h after hCG injection, in addition to the antral follicles, some large Graafian follicles could be observed in the rat ovaries, and the granulosa cells of these follicles were positively stained for aromatase. Each follicle was surrounded by the basal lamina which shows lineally distinct positive reaction against anti-laminin antibody. At 12 h after hCG injection, some large Graafian follicles without oocyte were weakly positive to the anti-aromatase antisera, and the outline of their basal lamina stained with anti-laminin antibody became irregular in shape and fragmentous. At 15 to 18 h after hCG injection, the luteinized cysts could be seen, and the granulosa-lutein cells of these cysts were almost negative for aromatase. Fragmentous reaction to the anti-laminin antibody was observed around the luteinized cysts. In the ovaries of day 4 in pregnancy, only the granulosa cells of the large antral follicles were weakly stained, but corpora lutea negatively reacted to the anti-aromatase antibody. At 7 to 19 days in gestation, both the granulosa cells of antral follicles and pregnant luteal cells were positively stained against aromatase antisera.(ABSTRACT TRUNCATED AT 250 WORDS)     

Infertility in a line of mice with the high growth mutation is due to luteal insufficiency resulting from disruption at the hypothalamic-pituitary axis.

Animals with extreme body growth frequently experience poor reproductive performance, but the cause for this association has not been clearly established. A line of mice homozygous for the high growth (hg) mutation, a mutation that has a major effect on post-weaning growth, exhibits several reproductive deficits including an abnormally high incidence of luteal failure. The objective of the present study was to investigate luteal failure in high-growth (HG) mice during pregnancy and to determine whether the cause of the apparent luteal failure resides in the ovary or the hypothalamic-pituitary unit. In HG females with a demonstrated history of infertility, progesterone injections (1 mg s.c. daily) beginning on Day 1 postcoitum (p.c.) increased the proportion of animals pregnant at Day 17 of gestation. Twice-daily injections of 100 microgram of ovine prolactin (PRL) in alkaline saline given to another group of females beginning on Day 1 p.c. increased the proportion of HG females that were pregnant on Day 6 of gestation compared with saline-injected HG females, although PRL did not increase the pregnancy rate in HG females when compared with a group of noninjected control females. When ovaries from HG females were transplanted into ovariectomized congenic C57 hosts, the C57 graft hosts displayed normal estrous cycles, and upon mating the majority of graft hosts became pregnant. In contrast, when ovaries from C57 females were transplanted into ovariectomized HG hosts, the HG graft hosts displayed normal estrous cycles, but upon mating most were unable to maintain pregnancy. These results suggest that the hypothalamic-pituitary unit of the HG female provides an inadequate signal to the ovaries to maintain pregnancy. Luteal failure in HG females may be due to insufficient PRL as required for establishment and early maintenance of the CL during pregnancy in mice.     

Post-partum oestrus in the little free-tailed bat, Tadarida (Chaerephon) pumila (Microchiroptera: Molossidae) at 24°S

Tadarida pumila exhibits post-partum oestrus in the sub-tropical latitudes of Southern Africa. Females nursing their first young of the season were either pregnant or had large Graafian follicles in their right ovaries. Further evidence that ovulation occurs soon after parturition was found in the ovaries, where follicles were developing alongside the corpora lutea of pregnancy. The latter indicates that oestrus occurs following parturition. Furthermore, as opposed to the first pregnancy of the season, the development of the endometrium was found to be less complete in the two subsequent pregnancies of that particular season. This is interpreted as being related to the very short interval between parturition and the following conception.     

Immunolocalization of cytochrome P450 17alpha-hydroxylase/c17-20 lyase in the ovary of pregnant pigs and fetal gonads

The study was designed to localize P450 17alpha-hydroxylase/c17-20 lyase (P450c17) in the ovaries of pregnant pigs and fetal gonads. Immunoexpression of P450c17 was investigated in the porcine ovaries (follicles and corpora lutea; CL) collected on days 10, 18, 32, 50, 70 and 90 post coitum (p.c.), and fetal gonads (testes and ovaries) on days 50, 70 and 90 p.c. The presence of P450c17 in ovarian follicles was demonstrated on all examined days of pregnancy but was restricted to theca interna cells. In CL, P450c17 was detected on all examined days of pregnancy but only in small luteal cells. In the female porcine fetuses, P450c17 immunostaining was found in oocyte nests and granulosa cells of primary ovarian follicles, while in the male fetuses in fetal Leydig cells. In conclusion, the immunolocalization of P450c17, detected in the ovaries of pregnant pigs and fetal porcine gonads, indicates the potential sites of androgen synthesis. We suggest that androgens may play a role in the maintenance of pregnancy and in the development of prenatal gonads in pigs.     

The structure of the spiny mouse (Acomys cahirinus) ovary during development

The study presents the structure of the ovaries of the spiny mouse (Acomys cahirinus) during the first months of life. The ovaries in neonate females exhibit a large number of primordial and primary follicles, sometimes clustered in nests. The growing follicles were also observed within the ovary at that period. The first, early antral follicles appeared in the ovary during the second week of life. In the group of 60-day old females, the structure of the ovaries was characterized by a significant increase in the connective tissue elements. Moreover, ovarian follicles at various stages of development were observed, except for the antral ones with cumulus oophorus. The first mature follicles were identified in 3-month old females. In the ovarian follicles, apoptosis occurs at all stages of follicle development, especially in the early antral follicles. In the atretic follicles, apoptotic cells were identified in the layer of granulosa cells.     

Prolonged lactational infertility in adolescent rhesus monkeys

The present study examined the effects of first pregnancy and nursing behavior on postpartum infertility in seasonally breeding rhesus monkeys to assess whether prolonged lactational infertility observed in adolescent mothers is due to a particular pattern of nursing or to decrements in body growth rates. After a successful first pregnancy, a significant percentage of the lactating adolescent mothers (57.1%; n = 8) failed to exhibit an ovulation with normal luteal phase during the subsequent breeding season. In contrast, the remaining lactating adolescents (42.9%, n = 6) and all of the adult mothers (100%, n = 6) exhibited ovulations with a normal luteal phase. Age alone was not the critical variable, since all nonlactating adolescents exhibited ovulations with normal luteal phase parameters in the subsequent breeding season. The luteal phase abnormalities exhibited by the subset of lactating adolescent females were characterized by an inadequate luteal phase (ILP) and by significantly lower serum levels of progesterone, estradiol, and bioactive luteinizing hormone. The occurrence of these ILP ovulations was associated with more frequent nursing bouts prior to ovulation and during the subsequent luteal phase. In contrast, nursing patterns for adult females who had ovulations with normal luteal phases were more similar to those of the infertile lactating adolescents exhibiting significantly longer and more frequent nursing bouts, suggesting that fully adult females may be less sensitive to the inhibitory aspects of a suckling stimulus. Differences in luteal phase function among lactating adolescents were not related to differential rates of ponderal or skeletal growth. A still-developing neuroendocrine system may thus render a significant proportion of adolescent females more sensitive to suckling-induced suppression of gonadotropin secretion.     

Development of infantile rat ovaries autotransplanted after cryopreservation by vitrification

We cryopreserved infantile rat ovaries by vitrification and assessed their viability by autotransplantation. Hemilateral ovarian transplantation was performed on rats on postnatal Days 10 to 12. The left ovary of each rat was dissected out, cryopreserved by vitrification using a modified vitrification solution (VS1), and then autotransplanted under the capsule of the right kidney. The right ovary of each rat was removed. For the control, the left ovary was dissected out from each rat and was immediately transplanted by the same procedure, without cryopreservation. Rats were nursed until weaning, and then the day of vaginal opening, estrous cyclicity from the day of vaginal opening until postnatal Day 84, and histology of ovarian grafts at postnatal Day 84 were examined. The time course of development of endocrine function of cryopreserved grafts was similar to that of fresh grafts. In ovarian transplants recovered on postnatal Day 84, antral follicles and corpora lutea (CL) were observed in addition to small follicles, although the number of antral follicles in cryopreserved grafts was smaller than in the fresh grafts. These results indicate that cryopreservation of ovarian tissue by vitrification can be used for the preservation of fertility and endocrine function of ovaries.