Ova In Oviducts Research Articles

Effect of ethanol extract of Portulaca oleracea L on ovulation and estrous cycle in female albino rats

BackgroundThe population control is major problem as it affects the socio-economic growth of the country. So in order to control population, family planning has been promoted through several methods of synthetic contraception, but synthetic drugs have more side effects hence there is need to search safe natural contraceptive drug from medicinal plants. The Portulaca oleracea L is traditional medicinal plants used for various pharmacological activities. MethodsThe present study was to know the effect of ethanol extract of P. oleracea L (Portulacea) on ovulation, estrous cycle, and uterine weight and biochemical changes in adult rats. Female rats weighing 100 g were divided into three experimental groups. Group I was administered with 0.2 ml of 1% Tween 80, served as negative control. Group II received 0.2 ml of 250 mg/kg of body weight of ethanol extract (low dose) and group III received 500 mg/kg of body weight of ethanol extract (high dose). All the above treatment was given for 15 days daily morning between 10 and 11 am to cover 3 cycles and vaginal smear was taken daily from all the group to monitor estrous cycle and ovulation. ResultsThe uterine muscle weight was recorded; ovulation was inhibited resulting in reduced number of ova in oviduct of the high dose treated rats (2.5 + 0.2) and moderate (5.7 + 1.1) in low dose when compared with control group (8.1 + 3.2). There is an increase (761.66 + 1.5275) of uterine weight of high dose treated rats compared to control group (222.66 + 2.5166). The ethanol extract at high dose (500 mg/kg of b. w) was found to possess estrogenic activity when tested in immature ovariectomized female albino rats. ConclusionThese findings proved the pharmacological basis for the traditional use of this plant for contraceptive purpose in India.

A synthetic peptide corresponding to amino acid residues 34 to 37 of human follicle-stimulating hormone beta-subunit accelerates the onset of puberty in male and female mice.

We have previously reported that a synthetic peptide amide corresponding to residues 34-37 (TRDL, threonine, arginine-aspartic acid-leucine) of the beta-subunit of human FSH induced prolonged vaginal estrus in normally cycling female mice (see Ref. 15). These results represented the first demonstration of an in vivo effect of a gonadotropin-related synthetic peptide on reproductive processes. We have extended these studies to examine possible effects of TRDL on the onset of puberty in female mice. In two replicated experiments, vehicle-injected control mice attained first vaginal estrus by day 39. An ip injection of 200 ug TRDL/g BW to 28-day-old prepubertal female mice, however, accelerated the onset of first vaginal estrus by 7 days in 11 of 12 (11/12) (Exp 1) and 7/9 (Exp 2) mice. Serum estradiol levels were significantly (P = 0.017) elevated in TRDL-treated mice, whereas progesterone was unchanged. Uteri of TRDL-treated mice were significantly (P = 0.003) heavier than uteri of vehicle-injected control animals of the same age and body weight. Intraluminal fluid accumulation (ballooning) at proestrus was absent in 20/21 TRDL-treated females, as were oviductal ova and ovarian corpora lutea. These phenomena are characteristic of the first estrous cycles of female mice isolated from males. To obtain further evidence for in vivo effects of TRDL, we assessed the ability of TRDL to accelerate the onset of puberty in male mice. When given as five consecutive daily ip injections of 200 ug/g BW to 28-day-old prepubertal male mice, TRDL significantly increased testis weight, when compared with vehicle-injected control mice of the same age and BW (171.3 +/- 3.8 mg vs. 151.6 +/- 4.3 mg, P = 0.001) and induced a 6.5-fold increase in serum testosterone levels. These studies confirm the previously reported in vivo activity of a synthetic peptide corresponding to human FSH-beta subunit 34-37 (TRDL) in adult female mice and extend its effects to the acceleration of the onset of puberty in immature male and female mice.

A Synthetic Peptide Corresponding to Amino Acid Residues 34 to 37 of Human Follicle-Stimulating Hormone -Subunit Accelerates the Onset of Puberty in Male and Female Mice

We have previously reported that a synthetic peptide amide corresponding to residues 34–37 (TRDL, threonine, arginine-aspartic acid-leucine) of the β-subunit of human FSH induced prolonged vaginal estrus in normally cycling female mice (see Ref. 15). These results represented the first demonstration of an in vivo effect of a gonadotropin-related synthetic peptide on reproductive processes. We have extended these studies to examine possible effects of TRDL on the onset of puberty in female mice. In two replicated experiments, vehicle-injected control mice attained first vaginal estrus by day 39. An ip injection of 200 ug TRDL/g BW to 28-day-old prepubertal female mice, however, accelerated the onset of first vaginal estrus by 7 days in 11 of 12 (11/12) (Exp 1) and 7/9 (Exp 2) mice. Serum estradiol levels were significantly (P = 0.017) elevated in TRDL-treated mice, whereas progesterone was unchanged. Uteri of TRDL-treated mice were significantly (P = 0.003) heavier than uteri of vehicle-injected control animals of the same age and body weight. Intraluminal fluid accumulation (ballooning) at proestrus was absent in 20/21 TRDL-treated females, as were oviductal ova and ovarian corpora lutea. These phenomena are characteristic of the first estrous cycles of female mice isolated from males. To obtain further evidence for in vivo effects of TRDL, we assessed the ability of TRDL to accelerate the onset of puberty in male mice. When given as five consecutive daily ip injections of 200 ug/g BW to 28-day-old prepubertal male mice, TRDL significantly increased testis weight, when compared with vehicle-injected control mice of the same age and BW (171.3 ± 3.8 mg vs. 151.6 ± 4.3 mg, P = 0.001) and induced a 6.5-fold increase in serum testosterone levels. These studies confirm the previously reported in vivo activity of a synthetic peptide corresponding to human FSH-β subunit 34–37 (TRDL) in adult female mice and extend its effects to the acceleration of the onset of puberty in immature male and female mice.

Spontaneous cortical granule release and alteration of zona pellucida properties during and after meiotic maturation of mouse oocytes

Exocytosis of cortical granules (CGs) and the concomitant electron density changes of the zona pellucida (ZP) in the absence of sperm penetration were investigated in mouse oocytes processed with tannic acid containing fixation at various stages during and after maturation. After fusion of the CG membrane with the plasma membrane, the CG contents became very electron-dense, due to tannic acid. CG material is seen to be made up of coarse granular structures which gradually change to fine amorphous structures, which accumulate within the developing perivitelline space (PVS). When the coarse CG material attaches to the ZP, small domains exhibiting higher electron density appeared, and the number of these domains gradually increased. Release of CG was observed from metaphase I through metaphase II. In metaphase I to immediately after ovulation, the higher electron density of ZP and CG release was restricted to the cortical area overlying the meiotic spindle. Finally, the CG-free domain formed itself overlying the meiotic spindle as a result of CG release. However, in oviductal ova, CG release additionally occurred in the hemisphere opposite the spindle. At this stage the entire PVS was well developed and contained numerous fine electron-dense materials. Moreover, the inner half of the ZP increased in electron density as well. This change in electron density of the ZP might be associated with released CG material. These results suggest that the "partial cortical reaction" may play an important role in conditioning the ZP prior to ZP reaction.

Localization of Oviductal Glycoproteins within the Zona Pellucida and Perivitelline Space of Ovulated Ova and Early Embryos in Baboons (Paplo Anubis)1

The estrogen-dominated baboon oviductal epithelium synthesizes and secretes a family of oviduct-specific glycoproteins. The objective of this study was to determine if these glycoproteins become associated with ova and early embryos. Ovarian and oviductal eggs obtained from superovulated baboons 72 h post-hCG were subjected to an indirect immunofluorescent assay that used a polyclonal antibody prepared toward the baboon oviduct-specific glycoproteins. Oviductal ova as well as 2-cell and 4-cell embryos showed intense, specific fluorescence within their zonae pellucidae. Ovarian ova did not exhibit fluorescence. Oviductal eggs were also fixed and processed for peroxidase-antiperoxidase immunocytochemistry and colloidal gold immunoelectron microscopy to confirm the immunofluorescent data and to determine the subcellular distribution of the antigens. Oviductal ova as well as 2-cell and 3-cell embryos exhibited immunolabeling localized within the zona. Gold particles were distributed uniformly throughout the width of the zona. Occasional groupings of gold particles were observed within the zona. Also, in most eggs, immunoreactivity was observed associated with flocculent material in the perivitelline space as well as the vitelline membrane. Furthermore, immunogold labeling above background level was noted in the cytoplasm of the eggs, particularly in the blastomeres of 3-cell embryos. Collectively, these results indicate that baboon estrogen-dependent oviductal secretory glycoproteins become intimately associated with oviductal ova and with embryos.

The Peak Phase of the Proestrous Prolactin Surge Is Blocked by Either Posterior Pituitary Lobectomy or Antisera to Vasoactive Intestinal Peptide*

The proestrous surge of PRL could result from a decrease in dopamine, an increase in PRL-releasing factor (PRF) or both. The objectives were to determine whether PRF from the posterior pituitary regulates the proestrous PRL surge, and to examine if there are interactions between PRF and vasoactive intestinal peptide (VIP). Posterior pituitary lobectomy (LOBEX) and passive immunization against VIP were employed. Adult cycling rats were subjected at 0900 h on proestrus to LOBEX or sham surgery (SHAM) under short term anesthesia, and were injected iv at 1330 h with 0.75 ml anti-VIP serum or normal rabbit serum. Jugular blood was collected hourly from 1400-2300 h and analyzed for PRL and LH by RIA. Oviductal ova were examined on estrus. The rise in plasma PRL in normal rabbit serum-treated SHAM rats was biphasic, with an early peak between 1500-1700 h and a lower plateau between 1900-2100 h. This rise was similar in profile and magnitude to that seen in intact rats. In contrast, LOBEX significantly attenuated the early peak, but did not alter the plateau. Passive immunization against VIP of either SHAM or LOBEX rats mimicked the effect of LOBEX alone on PRL release. Neither surgery nor anti-VIP serum affected the profile of the LH surge which was sharp and symmetrical, and all rats ovulated with 15-16 ova per rat. To determine whether VIP is the posterior pituitary PRF, selected tissues removed on proestrus or diestrus-1 were analyzed for VIP by RIA. VIP was undetectable (less than 20 pg/organ) in the posterior pituitary on either day examined. The contents of VIP in the anterior pituitary, medial basal hypothalamus, and paraventricular nuclei were unchanged between diestrus-1 and proestrus. The proestrous surge of PRL consists of two components: an early peak and a late plateau. The peak phase appears to be dependent on PRF input from the posterior pituitary. This input might be regulated by VIP, and interactions between the two could occur at the level of the hypothalamus, anterior pituitary, or both. The plateau phase of the PRL surge is independent of the posterior pituitary and VIP, and might involve hypothalamic dopamine.

Differential alterations in dopamine turnover rates in the stalk-median eminence and posterior pituitary during the preovulatory prolactin surge.

The relative contributions of dopamine (DA) and prolactin-releasing factor (PRF) in generating the preovulatory prolactin (PRL) surge were investigated. Immature female rats were injected with pregnant mare's serum gonadotropin (PMSG) on day 28. Jugular blood was collected hourly on days 30 and 31. PRL levels were low in the morning of day 30, rose 10-12 times to peak levels from 14.00 to 16.00 h, reached a prolonged plateau from 18.00 to 24.00 h, and reduced to basal levels in the morning of day 31. All PMSG-treated rats ovulated an average of 13-14 ova. PRL levels in age-matched control rats were low throughout this time, and no oviductal ova were present. DA turnover rates in the stalk-median eminence (SME) and posterior pituitary (PP) were determined from the decline in tissue DA after injecting alpha-methyl-p-tyrosine (alpha-MPT), a competitive inhibitor of tyrosine hydroxylase. DA turnover rates increased or were unaltered in the SME and PP, respectively, during the peak PRL phase as compared to presurge rates. In contrast, DA turnover rates were significantly reduced in both tissues during the plateau phase. The turnover rate in the SME, but not the PP, was increased in the morning of day 31. DA turnover rates in control rats never changed. Injection of alpha-MPT to PMSG-treated rats increased PRL levels at all times examined except during the plateau phase. Blood PRL levels were also determined in PMSG-treated rats following posterior pituitary lobectomy or sham lobectomy. The PRL surge was similar in both groups and all rats ovulated.(ABSTRACT TRUNCATED AT 250 WORDS)

Collagen-induced arthritis and pregnancy in mice: the effects of pregnancy on collagen-induced arthritis and the high incidence of infertility in arthritic female mice.

Collagen-induced arthritis (CIA) in mice is a model of inflammatory polyarthritis that has many features similar to human rheumatoid arthritis. In rheumatoid arthritis, pregnancy leads to amelioration of the disease while exacerbation develops after delivery. We used the CIA model to elucidate the role of pregnancy on disease and vice versa. The onset of arthritis in pregnant mice was delayed in the B10.RIII strains immunized with native porcine type II collagen 7-12 days prior to syngeneic [B10.RIII (susceptible to CIA) X B10.RIII] and allogeneic (B10.RIII female X B10.K male that are CIA resistant) pregnancy. In contrast, when mice were immunized on days 1-6 of pregnancy, the onset of arthritis was earlier as compared with controls. In addition, once the mice developed CIA after delivery, the disease showed markedly rapid progression as compared to the control immunized group. Humoral immune responses to type II collagen showed significantly decreased levels on day 14 (at late stage of pregnancy) both in syngeneic and allogeneic postmating immunized pregnant mice. The same effect was also seen in allogeneic premating immunized pregnant mice on day 21 (at mid-stage of pregnancy). The levels of these antibodies increased after delivery. Subclasses of IgG1 and IgG2a antibodies to type II collagen were suppressed during pregnancy. In the pseudopregnant group, these antibodies showed decreased levels on day 14, but did not differ from the control groups on day 21 and 28. Some immunoregulatory changes may play a role in these alterations in pregnant arthritic mice. In comparison to the effects of syngeneic (susceptible X susceptible) pregnancy on CIA, allogeneic (susceptible female X resistant male) pregnancy seemed to be beneficial for the affected individuals. Litter size and mean birth weight were not affected by immunization of type II collagen. After onset of CIA, both syngeneic and allogeneic matings failed to produce offspring in arthritic female mice. The estrus cyclicity was highly disturbed in arthritic female mice and gonadotropin stimulation in arthritic mice induced significantly less ova in oviducts and maturing follicles as compared to nonarthritic controls. Immunological factors yet to be elucidated may be involved in this ovarian dysfunction.

Chronic posterior pituitary lobectomy: prolonged elevation of plasma prolactin and interruption of cyclicity.

We previously reported that the posterior pituitary dopaminergic system participates in the inhibition of prolactin (PRL) secretion in both male and lactating female rats. However, posterior pituitary lobectomy (Lobex) of urethane-anesthetized cycling rats resulted in an elevation in plasma PRL for a short time only. This raises a question regarding the importance of input from the posterior pituitary to the control of PRL secretion during the estrous cycle. The objectives of this study were to examine the chronic effects of Lobex on plasma PRL levels in conscious rats and to determine whether the absence of input from the posterior pituitary interferes with estrous cyclicity. Lobex or sham lobectomy were performed under Brevital anesthesia in estrous rats. Blood was collected from jugular cannula at hourly intervals on the day of surgery and at 09.00, 13.00, and 17.00 h during the following 4 days. Daily water consumption and vaginal cyclicity were monitored for 14 and 20 days, respectively. Within 2 h after Lobex, the plasma PRL levels rose 3- to 4-fold and remained elevated for 3 days before declining to near control levels on the 4th day. None of the Lobex rats resumed cyclicity within 3-4 days, 50% had an interruption of cyclicity for 4-10 days, and the remainder were noncyclic for more than 11 days. Upon resumption of cyclicity, Lobex rats had 11.3 +/- 0.4 oviductal ova which is within the normal range for intact ovulating rats.(ABSTRACT TRUNCATED AT 250 WORDS)

Gonadal regression despite light pulses coincident with locomotor activity in the Syrian hamster.

Feedback lighting (LDFB), which illuminates an animal cage in response to active wheel running, exposes only the photosensitive portion of the phase-response curve to light. In the hamster, the photoinducible zone of the circadian rhythm of photoperiodic photosensitivity occurs during the interval of active wheel running. Since LDFB exposes the photoinducible zone almost as much as constant light (LL), we predicted that LDFB would maintain gonadal function just as LL does. Surprisingly, 10 male hamsters exposed to 1-sec pulses of LDFB for 8 wk had regressed testes similar to those of hamsters in continuous darkness (DD) and significantly smaller than hamsters exposed to LL (P less than 0.01). Two of 5 male hamsters exposed to 2-min pulses of LDFB underwent complete testicular regression and two had partially regressed testes. All females exposed to LDFB or to DD ceased showing cyclic signs of ovulation within 20 days, whereas most hamsters exposed to LL continued to show signs of cyclic ovulation. Six of the 8 hamsters exposed to LL had ova in their oviducts at autopsy, and also had significantly larger uteri (P less than 0.01) than hamsters exposed to DD or LDFB. None of the latter two groups (n = 6 and 9, respectively) had oviductal ova at autopsy. These results demonstrate that considerable exposure of the photoinducible zone to light does not necessarily maintain gonadal function. Light delivered to the photoinducible zone by LDFB may disrupt the normal alignment (internal coincidence) of circadian rhythms, thereby causing gonadal regression. Gonadal induction can occur when the photoinducible zone is exposed to light; however, it may not be the light itself, but rather the action of the light to alter the phase relationships of several oscillators, that causes induction and maintenance of the gonads.

Reproductive function following advanced ovulation induced by synthetic luteinizing hormone-releasing hormone in rats.

Reproductive function following advanced ovulation induced by a single injection of 1 microgram synthetic luteinizing hormone-releasing hormone (LH-RH) has been studied in rats. While advanced ovulation induced by an injection of the agent on the day of proestrus was followed by pregnancies occurring as frequently as those in spontaneous ovulation group, incidences of mating behavior, fertilization, and pregnancy were considerably reduced in the advanced ovulation group when induced by an injection of synthetic LH-RH during the early period of diestrus 2. The mean volume of primary oocytes of the three largest follicles at 1.00 h on the day of diestrus 2 was significantly smaller than that at 1.00 h on the day of proestrus. However, shortly before ovulation, the mean volume of secondary oocytes in the preovulatory follicles from rats treated with synthetic LH-RH at 1.00 h on the day of diestrus 2 was approximately the same as that in the preovulatory follicles from rats treated with the agent at 1.00 h on the day of proestrus. Shortly after ovulation the number of mitotic cumulus cells around the oviductal ova was significantly greater in advanced ovulation group induced by synthetic LH-RH injection during the early period of diestrus 2 than in spontaneous ovulation group. Furthermore, when examined 13 h after ovulation, the layers of cumulus cells were thicker, and cumulus cells were more tightly arranged around the ova in the advanced ovulation group induced by injection of synthetic LH-RH during the early period of diestrus 2 than those in the group with with spontaneous ovulation. These results suggest that the cumulus-oocyte complex from advanced ovulation group induced by injection of synthetic LH-RH in the early period of diestrus 2 is less potent in fertilizability than that from spontaneous ovulation group, leading to a reduction in the rate of subsequent pregnancy.

Superovulation induced by a single pituitary gland transplanted beneath the kidney capsule in adult rats.

Different numbers of rat pituitary glands, taken from male and female rats before and after puberty, were transplanted into various sites in female rats at different stages of the oestrous cycle. Ovulation was checked by counting ova in oviducts on the next expected day of ovulation. Ovulation was induced by transplantation beneath the kidney capsule in early dioestrus of half, one or three glands from 35- to 41-day-old male rats (18.6+/-3.1 (S.E.M.), 32.6+/-2.8 and 49.8+/-4.8 ova shed respectively). The transplantation of glands from mature female rats did not induce supraovulation but inhibited the expected ovulation. The most effective stage for inducing superovulation was early dioestrus and, to a lesser extent, most effective stage for inducing superovulation was early dioestrus and, to a lesser extent, oestrus; transplantation during late dioestrus was ineffective. The effective sites of transplantation were beneath the kidney capsule and intramuscularly but not subcutaneously. Representative pituitary glands from 35- to 41-day-old male rats and adult female rats were assayed for LH and FSH content to interpret the mechanisms of superovulation . The pituitary glands from the male rats contained larger amounts of LH and especially of FSH than those found in the female rats. The experiments indicated that superovulation can be induced successfully by the transplantation of a single pituitary gland from male and immature female rats without any additional treatment with human chorionic gonadotrophin; the failure of the female pituitary transplants to induce superovulation may be due to the insufficient content of LH and FSH.

Effects of urine from pregnant and lactating female house mice on oestrous cycles of adult females

It was demonstrated that mice treated with urine from pregnant or lactating females experienced longer periods of oestrus than did mice treated with water or urine from singly caged females. Application of urine by means of perforated capsules placed in the cage of the test mouse showed that the factor(s) responsible for the longer periods of oestrus was an airborne pheromone. The females experiencing longer oestrous periods ovulated (ova in oviducts), became pregnant and gave birth.

Retention of ova in oviducts of senescent mice and hamsters

Young (3-5 months of age) and senescent (12-17 months of age depending on the species) female mice, hamsters and rats were mated with young mature males and examined for numbers of degenerating ova. Young female mice, hamsters, rats and senescent rats exhibited normal numbers of ova following ovulation and, in general, normal numbers of blastocysts before implantation. In contrast, on the morning of ovulation some senescent mice and hamsters exhibited degenerating ova in the isthmus or isthmic-utero-tubal region of the oviduct, while normal ova were found in the ampulla. Degenerating ova were also located in the uterine horns of one mouse and hamster before implantation (day 3 of preganacy). Another hamster at the same stage of pregnancy exhibited 24 degenerating ova and nine blastocysts, all of which remained in the oviducts except for one blastocysts recovered from the uterus. In a previous study (Parkening and Soderwall, '75) a histological examination of the number of copora lutea from ovaries removed from senescent female hamsters whose oviducts contained large numbers of degenerating ova indicated the deteriorating ova were not ovulated following mating. Why ova from the previous unmated estrous cycle(s) remain in the oviducts of some senescent mice and hamsters remains to be determined.

The effects of tubal ligation on ovum transport in rabbits.

Ovum transport was studied in rabbit oviducts ligated 18 hr after mating in untreated and oestrogen-treated rabbits. Essentially all ova (93.5%) were recovered from the sham-ligated oviducts averaged 46.7%. Recovery of ova in oviducts ligated at the infundibulum and at the uterotubal junction was 100%. It is likely, therefore, that ova were transported prematurely into the uterus from ligated oviducts. Ovum transport through sham-ligated oviducts was significantly retarded by a single injection of oestradiol cyclopentylpropionate (25 or 250 mug) but remained accelerated in ligated oviducts diminished by 60 hr p.c. in untreated rabbits, but was maintained in oestrogen-treated rabbits. Ovum transport through distended oviducts may be accelerated by the passage of oviducal fluid into the uterus.

Studies on the reproduction in the dog. V. On cleavage and transport of fertilized ova in the oviduct

卵が排卵され卵管に進入すれば精子と会合できる条件にするため,実験雌犬19頭を排卵前(雄犬許容36時間目)に1回のみ交配させた。その後,排卵時期を開腹手術によって推定し,排卵後24時間から216時間までを24時間間隔に区分して,卵管,子宮角をそれぞれ3等分し受精卵を採取した。1.犬の排卵時の卵は第一卵母細胞で排卵後48~72時間の間に卵管内で成熟して第二卵細胞となって受精能を獲得する。2.受精卵の分割は排卵後72時間までは見られず,96時間で早いものは2細胞期,120時間で3~6細胞卵,144時間で8細胞卵,168時間で8または16細胞卵,192時間で16細胞卵,204~216時間で桑実胚となっていた。3.受精卵の卵管下降は,排卵後24,48時間では卵管中部,72時間で中間と下部,96~192時間で下部にそれぞれ達し,その後204~216時間では桑実胚となって子宮内に進入する。4.実験犬19頭中3頭(15.8%)において前回の発情に排卵されたと思われる卵が発見され,卵管下部に6ヵ月以上も残留していたとみられることがらが観察された。

Effects of Limbic Forebrain Ablation on Pituitary Gonadal Function in the Female Rat

Effects of limbic forebrain ablation on reproductive function were examined. Frontal cortex (Group A), septum (B), fornix (C), anterior limbic area (the area around anterior part of the hippocampus which located at rostral to the septal nuclei)(D), olfactory bulb (E), limbic cortex (F), and hippocampal formation (G) were ablated with suction, taking care not to damage the neighboring brain structures. Operations were performed under pentobarbital anesthesia on the day of estrus or diestrus I in 4-day cycling rats. Animals were autopsied 30 to 35 days postoperatively either on the day of proestrus or estrus. The preoptic basal hypothalamic region was intact in all examined rats.Various degrees of septal ablation suppressed the appearance of vaginal cornification for about 10 days, although the cycle resumed eventually. However, vaginal cycles became irregular predominantly diestrous for 9/14 of the septal-ablated rats. Normal ovulation occurred in 6 of 7 rats and significant changes in serum or pituitary LH and FSH were not observed. Complete ablation of the septum, however, reduced the weight of the uterus and the amount of intraluminal fluid.Ablation of the hippocampus induced slight increases in serum LH and FSH, and transection of the fornix increased serum LH, so that the hippocampus-fornix system seems to inhibit gonadotropin secretion. In these animals, cornified vaginal smears were absent for several days postoperatively, but the regular cycles were resumed subsequently. Normal ovulation as well as normal weights of ovaries, uterus and intraluminal fluid were observed.Ablation of the anterior limbic area disturbed the vaginal cycle for a few days postoperatively. Marked increase in serum and pituitary LH and FSH as well as increases in ovarian, uterine and adrenal weights and greater number of ova in oviducts were observed in these animals. Thus, this area of the brain consistently appears to exert an inhibitory influence on pituitary ovarian activity.No changes were observed in the rats with ablation of the frontal cortex, the olfactory bulb or the limbic cortex.Therefore, limbic forebrain structures is not essential for ovulation and maitenance of the estrous cycle, but appear to exert a significant modulating influence on pituitary gonadal function.

Sex Hormones and Their Effect Upon Conditioned Responses in the Rudd (Leuciscus Leuciscus)

ABSTRACT Since the effects of the sex hormones on the fish do not show any sex differences, the results of the experiments on both males and females can be summarized together. Oestrone inhibited an artificially produced conditioned response. Prolan and progesterone had no effect upon the functioning of the conditioned response, although several or prolonged injections of prolan are likely to cause inhibition due to natural causes, e.g. maturation of ova in oviducts. Progesterone, although foreign to the Pisces, terminates the inhibition brought about by previous injections of oestrone. Death caused by injection of progesterone can be prevented by injection of oestrone.