A Follicle Rupture Assay Reveals an Essential Role for Follicular Adrenergic Signaling in Drosophila Ovulation

Ovulation is essential for the propagation of the species and involves a proteolytic degradation of the follicle wall for the release of the fertilizable oocyte. However, the precise mechanisms for regulating these proteolytic events are largely unknown. Work from our lab and others have shown that there are several parallels between Drosophila and mammalian ovulation at both the cellular and molecular levels. During ovulation in Drosophila, posterior follicle cells surrounding a mature oocyte are selectively degraded and the residual follicle cells remain in the ovary to form a corpus luteum after follicle rupture. Like in mammals, this rupturing process also depends on matrix metalloproteinase 2 (Mmp2) activity localized at the posterior end of mature follicles, where oocytes exit. In the present study, we show that Mmp2 activity is regulated by the octopaminergic signaling in mature follicle cells. Exogenous octopamine (OA; equivalent to norepinephrine, NE) is sufficient to induce follicle rupture when isolated mature follicles are cultured ex vivo, in the absence of the oviduct or ovarian muscle sheath. Knocking down the alpha-like adrenergic receptor Oamb (Octoampine receptor in mushroom bodies) in mature follicle cells prevents OA-induced follicle rupture ex vivo and ovulation in vivo. We also show that follicular OA-Oamb signaling induces Mmp2 enzymatic activation but not Mmp2 protein expression, likely via intracellular Ca²⁺ as the second messenger. Our work develops a novel ex vivo follicle rupture assay and demonstrates the role for follicular adrenergic signaling in Mmp2 activation and ovulation in Drosophila, which is likely conserved in other species.     

Morphology and function of cryopreserved whole ovine ovaries after heterotopic autotransplantation

Background

The objective of this study was to perform complex characterization of cryopreserved and then autotransplanted ovaries including determination of the ability to respond to in vivo follicle stimulating hormone (FSH)-treatment, fertilizability of retrieved oocytes, and morphology, vascularization, cellular proliferation and apoptosis in sheep.

Methods

Mature crossbred ewes were divided into two groups; an intact (control) group (n = 4), and autotransplanted group (n = 4) in which oophorectomy was performed laparoscopically and ovaries with intact vascular pedicles frozen, thawed and transplanted back into the same animal at a different site. Approximately five months after autotransplantation, estrus was synchronized, ewes were treated with FSH, and ovaries were collected. For all ovaries, number of visible follicles was determined, and collected cumulus oocyte complexes (COC) were matured and fertilized in vitro. Remaining ovarian tissues were fixed for evaluation of morphology, expression of factor VIII (marker of endothelial cells), vascular endothelial growth factor (VEGF; expressed by pericytes and smooth muscle cells), and smooth muscle cell actin (SMCA; marker of pericytes and smooth muscle cells), and cellular proliferation and apoptosis. Two fully functional ovaries were collected from each control ewe (total 8 ovaries).

Results

Out of eight autotransplanted ovaries, a total of two ovaries with developing follicles were found. Control ewes had 10.6 +/- 2.7 follicles/ovary, oocytes were in vitro fertilized and developed to the blastocyst stage. One autotransplanted ewe had 4 visible follicles from which 3 COC were collected, but none of them was fertilized. The morphology of autotransplanted and control ovaries was similar. In control and autotransplanted ovaries, primordial, primary, secondary, antral and preovulatory follicles were found along with fully functional vascularization which was manifested by expression of factor VIII, VEGF and SMCA. Proliferating cells were detected in follicles, and the rate of apoptosis was minimal in ovaries of control and autotransplanted ovaries.

Conclusion

These data demonstrate successful autotransplantation of a portion of frozen/thawed ovaries manifested by restoration of selected ovarian function including in vitro maturation of collected oocytes, presence of follicles from several stages of folliculogenesis and blood vessels expressing specific markers of vascularization, and proliferation and apoptosis of ovarian cells. Thus, heterotopic autotransplantation of a whole frozen/thawed ovary allows for development of preovulatory follicles, oocyte growth, and for restoration of vascularization and cellular function. However, additional improvements are required to enhance the efficiency of autotransplantation of frozen/thawed ovaries to produce more oocytes.     

Influence of calcium and magnesium deprivation on ovulation and ovum maturation in the perfused rabbit ovary

The role of calcium (Ca++) and magnesium (Mg++) in the ovulation process was studied using in vitro perfused rabbit ovaries. Ovaries were perfused with or without human chorionic gonadotropin (hCG) in Ca++/Mg++-free medium (M199) alone or combined with standard M199 to yield varying concentrations of Ca++ and/or Mg++. In all ovaries perfused with hCG, ovulatory efficiency was similar regardless of the concentration of Ca++ and/or Mg++. In ovaries perfused in Ca++/Mg++-free medium without hCG, ovulatory efficiency was similar to that in ovaries perfused with hCG. As Ca++/Mg++ levels were increased without hCG, ovulatory efficiency declined. Ovulation time was significantly accelerated in ovaries perfused in Ca++/Mg++-free medium with or without hCG. Most ovulated ova from ovaries perfused without hCG were immature. With hCG, degree of ovum maturity was directly related to ovulation time. Ovarian smooth muscle contractions were undetectable in 3 ovaries perfused in Ca++/Mg++-free M199 despite occurrence of ovulation. Smooth muscle contractions were recorded in 2 of 3 ovaries perfused in standard M199 with hCG. These results indicate: 1) Ca++/Mg++ exclusion results in rapid follicle rupture and immature ova; 2) oocyte maturation appears to be gonadotropin-dependent; 3) ovulation occurs in the absence of ovarian smooth muscle contractions during perfusion with Ca++/Mg++-free medium.     

The distribution of smooth muscle in the cat ovary with a note on its adrenergic innervation

Smooth muscle in the ovaries of estrus and anestrus cats was studied with the TP-Levanol Fast Cyanine 5 RN technique and adrenergic nerves were visualized with the Falck-Hillarp fluorescence procedure. Numerous bundles of smooth muscle fibers were observed in the mesovarium, and the hilar, medullary, and cortical regions of the estrus ovary. Also, theca externa of large vesicular follicles contained many smooth muscle fibers. Adrenergic nerves with varicosities were present in ovarian perifollicular tissue. Anestrus animals had a reduced number of cortical and perifollicular muscle fibers and the intensity and density of fluorescent nerves was reduced. It is suggested that contraction of ovarian smooth muscle facilitates ovulation. These contractions may be, at least partially, under local neural control.     

Intraovarian relationships among dominant and subordinate follicles and the corpus luteum in heifers

Previous studies demonstrated that waves of follicular activity develop approximately every 9 d in cattle during the estrous cycle and early pregnancy. A dominant follicle develops from each wave and the remaining follicles (subordinates) begin to regress after a few days. In this study, intraovarian luteal and follicular interrelationships were examined during the follicular waves of the estrous cycle and pregnancy using data obtained by ultrasonography. During the estrous cycle, no intraovarian relationships were found between the ovary containing the corpus luteum and the ovary containing the dominant follicle (n = 165), or between the location of the corpus luteum and the characteristics of the dominant follicle. During pregnancy, however, the frequency distribution for the number of follicular waves with the dominant follicle and corpus luteum on the same or opposite ovaries differed (P<0.05) among Waves 1 to 10. The two structures (dominant follicle and corpus luteum) were more often in opposite ovaries during Waves 3 to 10 (combined frequency, 75%) than during Waves 1 and 2. During pregnancy, dominant follicles of consecutive waves differed (P<0.05) among Waves 1 to 8 in the frequency with which they appeared in the same versus the opposite ovary. The difference seemed primarily due to an increased frequency of consecutive follicles on the same ovary for Waves 4 to 8 (combined frequency, 80%). During both the estrous cycle and pregnancy, there was no significant intraovarian effect of the dominant follicle on the day of detection of the next dominant follicle, on the growth rate of the largest subordinate follicle, or on the length of the interval from wave origin to cessation of growth of the largest subordinate; these results indicate that previously postulated suppressive effects between follicles are exerted through systemic channels.     

Ultrastructure and melatonin 1a receptor distribution in the ovaries of African ostrich chicks

Healthy 90-day-old ostrich chicks were used in the present study. The ultrastructure and melatonin 1a receptor (MT1) distribution in the ovaries of ostrich chicks was observed by transmission electron microscope and light microscope. The results showed that the ostrich chick ovary contained primordial follicles, primary follicles and secondary follicles, but no mature follicles. There are some unique ultrastructural characteristics observed in the secondary follicle, such as the cortical granule, which was located in cytoplasm beside the nucleus and appeared first in the oocyte. The zona radiata appeared in the secondary follicle, and there was an obvious vitelline membrane. There were intraovarian rete, connecting rete, and extraovarian rete in the ovaries of ostrich chicks. This is the first study that provides immunohistochemical evidence for the localization of the melatonin MT1 in the ostrich chick ovary. The germinal epithelium, follicular cell layer of every grade of follicle, cytoplasm of the oocyte and interstitial cells all expressed MT1. The expression of positive immunoreactivity materials was the strongest in the follicular cell layer of the primordial follicle and germinal epithelium, was weaker in the follicular cell layer of the primary follicle and secondary follicle, and was weakest in the oocytes of all grades of follicle. In addition, the extraovarian rete displayed strong positive expression of MT1, while there was no positive expression in the intraovarian rete or connecting rete. The positive expression of MT1 immunoreactivity in the ovary was very strong, implying that the ovary is an important organ for synthesizing MT1.     

Studies on the morphology of the isolated perfused rabbit ovary

Summary Ovulation was induced in rabbits by intravenous administration of human chorionic gonadotrophin (HCG), and 4–5 h later the ovaries were isolated and introduced into an in-vitro perfusion system containing synthetic medium with albumin. Rupture of follicles occurred in vitro within the physiological time range (mean 11.3 h after injection of HCG), although with a reduced frequency. Preovulatory and ruptured follicles were studied in detail by light and electron microscopy.In the granulosa layer of ruptured or preovulatory follicles cytoplasmic blebbing activity, disappearance of CallExner bodies and differentiation toward luteinized cells were found. Perhaps the most important sign of normal preovulatory development in vitro was that the basement membrane surrounding the granulosa layer was penetrated by projections of granulosa cells. In the absence of this penetration phenomenon the granulosa layer prolapsed out of the follicle. Immediately before rupture, follicles showed marked degeneration, restricted to the outer layers of the apical wall, which is compatible with the hypothesis that degradative enzymes are released close to the surface of preovulatory follicles.Although the majority of follicles that ovulated under in-vitro conditions showed the same kind of morphological alterations as can be seen in vivo, occasional atypical ruptures occurred without any overt signs during perfusion. Also technical manipulations of the perfusion system, e.g., nonphysiological increase of perfusion pressure, could force follicles to rupture. This illustrates the importance of careful morphological study of all ovaries perfused in vitro before conclusions are drawn.     

Arrangement and structure of sinus hair muscles in the big-clawed shrew,Sorex unguiculatus

The arrangement and structure of sinus hair muscles in the snout of the shrew, Sorex unguiculatus, were studied by electron microscopy and serial section light microscopy. Both striated and smooth muscles are directly associated with sinus hair follicles. The striated muscle fibers originate from the base of a follicle and insert onto the superficial portion of adjoining caudally positioned follicles. Some fibers insert into the corium instead of inserting into a follicle. The fibers show a fine structure typical of red fibers. Smooth muscle cells form a network with elastic fibers beneath the corium. Some cells are directly attached to the capsule of the sinus, thus forming a type of M. arrector pili. Striated muscle fibers that appear to end in the corium are connected with the smooth muscle network through the elastic fibers which appear to function as the tendon of these two types of muscle cell.     

Immunohistochemical localization of tissue-type plasminogen activator in ovaries before and after induced and spontaneous ovulation in the rat

Summary The observation that tissue-type plasminogen activator (tPA) activity increased dramatically in preovulatory follicles has led to the hypothesis that plasminogen activation is causally related to follicle rupture. With immunohistochemistry, we have studied the appearance of tPA in ovaries of immature rats induced to ovulate and in adult cycling rats. Treatment of immature female rats with a single dose of pregnant mare serum gonadotropin (PMSG) induced follicular maturation. A subsequent human chorionic gonadotropin (hCG) injection resulted in follicle rupture 12–14 h later. PMSG treatment alone did not induce appearance of tPA-immunoreactive cells in any ovarian compartment. After hCG stimulation, however, theca cells, granulosa cells, and oocytes of pre- and postovulatory follicles displayed distinct tPA immunoreactivity. Fibroblastlike cells in the theca layers and tunica albuginea of the follicle apex also demonstrated localized cytoplasmic tPA reactivity. In addition to tPA synthesis in preovulatory follicles, hCG also induced tPA staining in the theca (but not granulosa) layers of non-ovulatory follicles. At 24 h after hCG treatment, there was a marked tPA staining in developing corpora lutea, ovulated ova, and oviductal epithelium. Ovaries from regularly cycling adult rats displayed a similar ovulation-related pattern of tPA immunostaining. The appearance of tPA in different cell types of the preovulatory follicle and in the fibroblast-like cells at the follicle apex, strengthens the hypothesis of a direct involvement of tPA in follicle rupture. Presence of tPA in postovulatory oocytes, cumulus cells, and surrounding oviductal epithelium may also indicate a role for tPA in the transfer of eggs in the oviduct.This work was supported by NIH Research Grants HD-14084; 12303     

The effects of CLP-induced sepsis on proliferation and apoptosis of granulosa and theca cells in rat ovary: A histochemical and ultrastructural study

Sepsis is defined as a systemic inflammatory response to infection. This study is aimed to evaluate the effects of experimental sepsis on the proliferation and apoptosis of granulosa and theca cells in the rat ovary.28-day-old immature Wistar-Albino female rats were treated with pregnant mare serum gonadotrophin to develop the first generation of preovulatory follicles. Sepsis was induced by cecal ligation and puncture (CLP). Following in vivo 5-Bromo-2-deoxyuridine (BrdU) labeling, animals were sacrificed and ovaries were embedded in paraffin and Epon. Besides electron microscopic evaluation, BrdU, cleaved caspase-3, p27 immunostaining, and TUNEL labeling were performed.In CLP-operated animals, cleaved caspase-3 immunoreactivity was significantly increased in Graafian follicles. TUNEL and BrdU labeling in the ovarian follicles were not statistically different between CLP and sham-operated rats. In septic animals, p27 immunoreactivity was increased significantly in the nuclei of oocytes and decreased in the cytoplasm of granulosa and theca cells in multilaminar primary follicles compared to the sham group. In ultrastructural evaluation, increased apoptosis was observed in theca interna and granulosa cells in both the early and late stages of follicles in the CLP group.In conclusion, experimentally-induced sepsis leads to apoptosis in ovarian follicles at advanced stages of development. Our data suggest that although sepsis may not cause a potential threat to developing follicles at least in the short term, more severe damage may occur during advanced stages of follicle development.     

Magnetic resonance imaging for the study of ovarian follicles in the mouse

Additional tools to analyze follicle development would be highly advantageous because current methods require sacrifice of animals at specific times and time-consuming sectioning of tissues for histologic analysis. Magnetic resonance imaging (MRI) may provide a less involved, faster and more cost-effective method to analyze follicles in whole ovaries. Fixed ovaries were collected at different stages of the estrus cycle and after stimulation with gonadotrophins (24 and 48 h post pregnant mares serum (PMSG), and 10 and 24 h post human chorionic gonadotrophin (hCG)) with or without administration of the contrast agent gadodiamide. The MR images were generated using a vertical-bore, 11.7 Tesla MR system. Analysis of the MR images revealed large antral follicles in fixed ovaries with the oocyte and cumulus mass identifiable within preovulatory follicles. The use of gadodiamide had no impact on the quality of MR images obtained. The fixed ovaries were paraffin embedded, sectioned, and hematoxylin stained. Follicles were counted using the MR images and the histology sections. Preovulatory follicle numbers determined using MR images were comparable to those using histology; however counts of smaller follicles were inconsistent. MRI of gonadotrophin-stimulated ovaries in situ did not reveal discernable ovarian structures. Therefore, MRI is a useful tool for studying whole fixed ovaries leaving the ovary intact for additional analyses or for selection of samples based on morphology. The MRI is also useful for identifying preovulatory follicles, although analysis of smaller follicles is not possible, and thus the potential exists for cyst analysis in mouse models of polycystic ovarian syndrome (PCOS).     

Loss of inhibin alpha uncouples oocyte-granulosa cell dynamics and disrupts postnatal folliculogenesis

Targeted disruption of the inhibin α gene (Inha^-/-) in mice results in an ovarian phenotype of granulosa cell tumors that renders the animals infertile. Little is known about the reproductive defects prior to tumor development. Here, we report novel data on early follicle dynamics in Inha^-/- mice, which demonstrate that inhibin α has important consequences upon follicle development. Morphological changes in both germ and somatic cells were evident in postnatal day 12 ovaries, with Inha^−/− mice exhibiting numerous multilayered follicles that were far more advanced than those observed in age-matched controls. These changes were accompanied by alterations in follicle dynamics such that Inha^−/− ovaries had fewer follicles in the resting pool and more committed in the growth phase. Absence of inhibin α resulted in advanced follicular maturation as marked by premature loss of anti-Müllerian hormone (AMH) in secondary follicles. Additionally, gene expression analysis revealed changes in factors known to be vital for oocyte and follicle development. Together, these data provide key evidence to suggest that regulation of the inhibin/activin system is essential for early folliculogenesis in the prepubertal mouse ovary.     

Intraovarian effect of dominant follicle and corpus luteum on number of follicles during a follicular wave in heifers

The intraovarian relationships among dominant follicle (DF), corpus luteum (CL), and number of follicles between Days 0 to 5 (Day 0 = ovulation) in wave 1 (n = 65 waves) and Days 9 to 13 in wave 2 (n = 62) were analyzed in separate experiments in Bos taurus heifers. Ovaries were grouped into intraovarian patterns of DF–CL, DF alone, CL alone, and neither DF nor CL. In wave 1, the pattern frequencies of DF–CL or neither DF nor CL (34% each) were greater (P < 0.0004) than for DF alone or CL alone (16% each). The number of growing follicles ≥5.0 mm, was greater (P < 0.0001) in ovaries with the DF, even when the DF was removed from the tally (P < 0.03). In a factorial analysis of wave 1, there was a positive main effect of DF (3.9 ± 0.2 vs. 2.2 ± 0.2 follicles; P < 0.0001), but the main effect of CL and the interaction of DF and CL were not significant. In a factorial analysis of wave 2, there were more (P < 0.0001) follicles greater than 6 mm in ovaries with a DF when the DF was included and an approaching difference (P < 0.09) when the DF was excluded. The main effect of CL and the interaction of DF and CL were not significant. The hypothesis that both the DF and CL have a positive intraovarian effect on number of follicles in waves 1 and 2 was only partly supported; the DF, but not the CL, had an effect in the factorial analyses. Previous reports in cattle and sheep of a positive intraovarian effect of CL on number of follicles are questionable in that location of the DF was not considered.     

Primordial follicle activation is affected by the absence of Sohlh1 in mice

Previous studies have reported that only primordial follicles and empty follicles can be found in 7.5 days postparturition (dpp) Sohlh1^?/? mouse ovaries and females are infertility. There appears to be a defect in follicle development during the primordial‐to‐primary follicle transition in Sohlh1^?/? mouse ovaries. However, detailed analyses of these phenomena have not been performed. In this study, we used Sohlh1^?/? transgenic mice to explore the role of Sohlh1 in folliculogenesis. The results showed that only primordial follicles and empty follicles can be observed in Sohlh1^?/? ovaries from 0.5 to 23.5 dpp. The expression of Foxo3 and FOXO3 was downregulated; nucleocytoplasmic shuttling of FOXO3 was normal in 7.5‐dpp Sohlh1^+/+ but not Sohlh1^?/? ovaries; and primordial follicle activation (PFA) was not observed in 7.5‐dpp Sohlh1^?/? mice. The expression levels of KIT, AKT, and P308‐AKT were downregulated (p < 0.05), whereas that of P473‐AKT was not significantly changed (p > 0.05). The KIT/PI3K/AKT pathway was inhibited. Furthermore, we conducted a dual luciferase assay and chromatin immunoprecipitation. The results showed that SOHLH1 can upregulate the Kit gene by binding to the ?3698 bp E‐box motif. The absence of Sohlh1 may affect PFA in mouse ovaries via downregulation of Kit and inhibition of the KIT/PI3K/AKT pathway.     

Feed restriction in cyclic gilts: gonadotrophin-independent effects on follicular growth

Our objective was to determine whether changes in metabolic hormones, induced by feed restriction, can alter follicle distribution in swine ovaries through effects independent of LH pulsatility. In a factorial arrangement, 24 gilts were fed a high or a low level of dietary energy (240 or 80% of maintenance requirements) and given an antagonist of GnRH or saline between days 3 and 12 of the oestrous cycle. Serial blood samples were collected on day 12 and ovaries on day 13. Antagonist treatment, that blocked LH pulsatility, decreased the number of follicles larger than 2 mm and increased the number of follicles smaller than 1 mm. The feed restriction did not alter gonadotrophin secretion, decreased the number of follicles smaller than 1 mm and increased the number of 1 - to 1.9-mm follicles. These findings indicate that feed restriction can alter the growth of small follicles independently of gonadotrophin levels.     

Effect of prostacyclin on myogenic activity and adrenergic neuroeffector interaction in canine isolated veins

In isolated strips of canine mesenteric vein prostacyclin (PGI₂) causes a dose-dependent depression of the amplitude of the spontaneous rhythmic contractions without influencing their frequency. This suggests that prostacyclin affects the events leading from the depolarization of the smoole muscle cells to their contractions, rather than the induction of the myogenic activity itself. Furthermore, prostacyclin reduces the noradrenaline-induced contraction of the canine saphenous vein without affecting the electrically induced responses, suggesting a possible dual effect of the drug: at the smooth muscle it causes depression of the responsiveness to noradrenaline whereas at the adrenergic nerve endings it enhances the evoked release of the adrenergic transmitter.     

Fibroblast growth factor 18 regulates steroidogenesis in fetal bovine ovarian tissue in vitro

In cattle and other species, the fetal ovary is steroidogenically active before follicular development commences, and there is evidence that estradiol and progesterone inhibit follicle formation and activation. Estradiol levels decline sharply around the time of follicle formation. In the present study, we hypothesized that FGF10 and FGF18, which inhibit estradiol secretion from granulosa cells of antral follicles, also regulate fetal ovarian steroid production. Fetuses were collected at local abattoirs, and age determined by crown‐rump length measurements. Real‐time polymerase chain reaction assays with RNA extracted from whole ovaries revealed that the abundance of CYP19A1 messenger RNA (mRNA) decreased from 60 to 90 days of gestation, which is consistent with the decline in estradiol secretion previously observed. Immunohistochemistry revealed the presence of FGF18 in ovigerous cords in early gestation and in oocytes later in fetal age (≥150 days). The abundance of FGF18 mRNA increased after Day 90 gestation. Addition of recombinant FGF18 to fetal ovarian pieces inhibited estradiol and progesterone secretion in vitro, whereas FGF10 was without effect. Consistent with these results, FGF18 decreased levels of mRNA for CYP19A1 and CYP11A1 in ovarian pieces in vitro. These data suggest that FGF18 may be an intraovarian factor that regulates steroidogenesis in fetal ovaries.     

In vivo evidence of role of bone morphogenetic protein-4 in the mouse ovary

The transition of a primordial follicle to a primary follicle is an early step in folliculogenesis. All female mammals are born with a fixed stock of primordial follicles, and exhaustion of that stock leads to menopause or infertility. Recently, several in vitro studies have indicated that BMP-4, BMP-7, and several other growth factors affect the transition of primordial to primary follicles. The aim of our present study was to investigate role of BMP-4 in this process using passive immunization to investigate the role of BMP-4 in a prepubertal mouse model. After seven days of treatment, the weight of antiBMP-4 treated ovaries was significantly lower than the ovaries from mice treated with nonimmune Ig. The number of primary follicles was lower, and the numbers of primordial follicles were higher in antiBMP-4 treated ovaries compared to control ovaries. Treatment with equine chorionic gonadotrophin (eCG) showed no influence on the effects of antiBMP-4 in the mouse ovary. Thus, the results of our study indicate that in vivo BMP-4 acts as transition factor in transition of primordial to primary follicle.     

Ultrastructural comparison of smooth muscle from ovarian follicle and oviduct of the golden hamster

Summary Ultrastructural characteristics of smooth muscle taken from ovarian follicles and oviducts of hamsters are compared. Differences between the two muscle types are more quantitative than qualitative, thus confirming that follicular muscle is a true smooth muscle with no unique characteristics. While both muscle types contain 50–80 Å filaments, -glycogen deposits, and organelles characteristically found in smooth muscle, the oviductal cells have substantially more sacs, tubular structures, sarcoplasmic reticulum, and mitochondria. Another difference concerns the cellular junctions; the oviductal cells exhibit nexuses, whereas the follicular cells show desmosomelike junctions. Based on ultrastructural differences, follicular smooth muscle seems to be a relatively toneless muscle suited for short, infrequent contractions, whereas oviductal smooth muscle is probably involved in more active tonic contractions.Supported by an Institutional Research Grant from Texas Women's University, by NIH Grant HD 12988, and by the Department of Anatomy at Wright State University     

Studies on morphological features of foetal and adult ovaries in Kano brown goats

In this work we studied the structures of 51 foetal and 14 adult ovaries obtained from slaughtered Kano brown does in Nsukka abattoir. The ages of the adult does were determined by dentition and foetuses by crown rump length method. The foetal and adult ovaries were divided into five different groups using specific age intervals as Gestation day (GD) 50–65, 66–95, 96–125 and 126–145 and adults. For histological studies the ovaries were fixed, processed and routinely stained with H&E. The ovarian follicles were classified into 5 types according to granulosa cell layers surrounding the oocytes. The number of ovarian follicles per microscopic field, number of granulosa cells surrounding type 1 and 1A follicles and diameter of the ovarian follicles were determined for each group at 400× magnification. Grossly the foetal ovaries were like pin head, oval in shape, uniformly smooth and creamy in colour. The adult ovaries had follicles with different sizes. The adult mean ovarian weights were significantly higher (P < 0.01) than those of the foetuses. Microscopically, the GD 50–65 ovaries had no distinct cortex and medulla. Oogonia were numerous among other stromal cells toward the periphery of the ovary. By GD 66–95 the ovaries contained types 1, 1a, 2 and 3 follicles. GD 96–125 ovaries contained type 4 follicles with early antrum formation and those of GD 126–145 comprised type 5 among other follicles. The adult ovaries comprised all the ovarian follicle types. The number of type 1 follicles increased significantly (P < 0.01) with foetal age. It was least in the adults. The diameter of adult follicles was significantly higher (P < 0.01) than those of the foetuses. This result provides baseline information on the morphological development of ovaries in Kano brown goats.