bluuebunny/crossref_metadata_2025 huggingface dataset:
Mechanisms for Dominant Follicle Selection in Monovulatory Species: A Comparison of Morphological, Endocrine and Intraovarian Events in Cows, Mares and Women
Authors: Mihm M , Evans ACO
Published: July 2008

Contents

The selection of a single ovarian follicle for further differentiation and finally ovulation is a shared phenomenon in monovulatory species from different phylogenetic classes. The commonality of dominant follicle (DF) development leads us to hypothesize that mechanisms for DF selection are conserved. This review highlights similarities and differences in follicular wave growth between cows, mares and women, addresses the commonality of the transient rises in FSH concentrations, and discusses the follicular secretions oestradiol and inhibin with their regulatory roles for FSH. In all three species, rising FSH concentrations induce the emergence of a follicle wave and cohort attrition occurs during declining FSH concentrations, culminating in DF selection. Cohort secretions are initially responsible for declining FSH, which is subsequently suppressed by the selected DF lowering it below the threshold of FSH requirements of all other cohort follicles. The DF acquires relative FSH‐independence in order to continue growth and differentiation during low (cow, mare) or further declining FSH concentrations (women), and thus may be the one cohort follicle with the lowest FSH requirement due to enhanced FSH signalling. In all three monovulatory species a transition from FSH‐ to LH‐dependence is postulated as the mechanism for the continued development of the selected DF. In addition, FSH and IGF enhance each other’s ability to stimulate follicle cell function and access of IGF‐I and ‐II to the type 1 receptor is regulated by IGF binding proteins that are in turn regulated by specific proteases; all of which have been ascribed a role in DF development. No fundamental differences in DF selection mechanisms have been identified between the different species studied. Thus functional studies of the selection of DFs in cattle and mares are also valuable for identifying genes and pathways regulating DF development in women.
Regulation of Luteal Function and Corpus Luteum Regression in Cows: Hormonal Control, Immune Mechanisms and Intercellular Communication
Authors: Skarzynski DJ , Ferreira‐Dias G , Okuda K
Published: July 2008

Contents

The main function of the corpus luteum (CL) is production of progesterone (P4). Adequate luteal function to secrete P4 is crucial for determining the physiological duration of the oestrous cycle and for achieving a successful pregnancy. The bovine CL grows very fast and regresses within a few days at luteolysis. Mechanisms controlling development and secretory function of the bovine CL may involve many factors that are produced both within and outside the CL. Some of these regulators seem to be prostaglandins (PGs), oxytocin, growth and adrenergic factors. Moreover, there is evidence that P4 acts within the CL as an autocrine or paracrine regulator. Each of these factors may act on the CL independently or may modify the actions of others. Although uterine PGF2α is known to be a principal luteolytic factor, its direct action on the CL is mediated by local factors: cytokines, endothelin‐1, nitric oxide. The changes in ovarian blood flow have also been suggested to have some role in regulation of CL development, maintenance and regression.
Captive Breeding of Cheetahs in South Africa – 30 Years of Data from the de Wildt Cheetah and Wildlife Centre
Authors: Bertschinger HJ , Meltzer DGA , Van Dyk A
Published: July 2008

Contents

The de Wildt Cheetah and Wildlife Centre was established in 1971 and the first cheetah cubs were born in 1975. During the period 1975–2005, 242 litters were born with a total of 785 cubs. Mean cub survival from 1 to 12 months and greater than 12 months of age was 71.3 and 66.2%, respectively. The majority of losses (84.9%) occurred during the first month postpartum whereas only 15.1% deaths took place between 1 and 12 months of age. Females were first bred at an age of approximately 3 years, reached maximum reproductive age at 6–8 years, where after fertility declined. Males reached peak reproduction at 6 and maintained this for up to 12 years of age. Male fertility was best correlated with sperm morphology. During recent years, for practical purposes, males were allocated to ‘good’ (≥70% normal), ‘fair’ (40–70% normal) and ‘poor’ (<40% normal) categories according to sperm morphology count. The breeding males were selected from the good (preferably) and fair categories but poor category males were also used at times. Average litter sizes for ‘good’, ‘fair’ and ‘poor’ males were 3.44 (n = 21), 3.14 (n = 18) and 2.28 (n = 18), respectively. In females the heritability for litter size was high at 0.5848 (532 progeny, 1975–2007) and the maternal heritability for cub mortality was estimated to be 0.596. The data from the de Wildt Cheetah and Wildlife Centre and two other centres in the world (Kapama and Wassenaar) demonstrate that cheetah can be bred successfully in captivity.
Non‐invasive Monitoring of Hormones: A Tool to Improve Reproduction in Captive Breeding of the Eurasian Lynx
Authors: Dehnhard M , Naidenko S , Frank A , Braun B , Göritz F , Jewgenow K
Published: July 2008

Contents

The survival of many critical endangered mammal species is often depending on successful captive breeding programmes which include the future option of reintroduction to the wild. Breeding in captivity also demands the application of modern assisted reproductive techniques to ensure maximal biodiversity, but knowledge on reproductive physiology is often limited. Therefore, non‐invasive monitoring of urinary and faecal hormones has become an important tool for reproductive management. To exemplify the importance of non‐invasive hormone monitoring, we choose the Eurasian lynx as a model for the world’s most endangered felid species, the Iberian lynx. We analysed faecal samples of pregnant and pseudo‐pregnant female Eurasian lynxes during a 3‐year study period. Compared to pre‐mating levels faecal progesterone metabolite profiles revealed a tendency towards higher levels in pregnant and pseudo‐pregnant females with no difference between both categories. Oestrogen levels raised in both pregnant and pseudo‐pregnant females with a tendency to be more elevated and prolonged in pregnant females. Surprisingly both E2 and P4 metabolites were highly correlated (r2 =0.8131, p < 0.0001) showing a postpartum increase both in pregnant and pseudo‐pregnant females. The results from the Eurasian lynx revealed that the measurement of faecal progesterone metabolites led to profiles dissimilar to profiles shown in other felid species, but similar to those from faecal gestagen metabolite analysis in the Iberian lynx. To identify faecal gestagen and oestrogen metabolites a radio‐metabolism study was performed. Using the progesterone immunoassay two major progesterone metabolites were detected demonstrating that the assay indeed tracks the relevant metabolites. The oestrogen assay measured authentic 17β‐oestradiol and oestrone, and their conjugates. The analysis of the faecal metabolite composition in samples from early and late pregnancy and lactation particularly revealed a distinct shift in the relation between 17β‐oestradiol and oestrone that changed in favour of oestrone. This might indicate different hormone sources during and after pregnancy (corpus luteum, placenta). We hypothesize, that placental steroid analysis in combination with other highly sophisticated analytical techniques, like liquid chromatography mass spectrometry or urinary relaxin analysis may led to analytical options to confirm pregnancy and to differentiate this from pseudo‐pregnancy in lynx species.
Improved Detection of Reproductive Status in Dairy Cows Using Milk Progesterone Measurements
Authors: Friggens NC , Bjerring M , Ridder C , Højsgaard S , Larsen T
Published: July 2008

Contents

This study tested a model for predicting reproductive status from in‐line milk progesterone `measurements. The model is that of Friggens and Chagunda [Theriogenology 64 (2005) 155]. Milk progesterone measurements (n = 55 036) representing 578 lactations from 380 cows were used to test the model. Two types of known oestrus were identified: (1) confirmed oestrus (at which insemination resulted in a confirmed pregnancy, n = 121) and (2) ratified oestrus (where the shape of the progesterone profile matched that of the average progesterone profile of a confirmed oestrus, n = 679). The model detected 99.2% of the confirmed oestruses. This included a number of cases (n = 16) where the smoothed progesterone did not decrease below 4 ng/ml. These cows had significantly greater concentrations of progesterone, both minimum and average, suggesting that between cow variation exists in the absolute level of the progesterone profile. Using ratified oestruses, model sensitivity was 93.3% and specificity was 93.7% for detection of oestrus. Examination of false positives showed that they were largely associated with low concentrations of progesterone, fluctuating around the 4 ng/ml threshold. The distribution of time from insemination until the model detected pregnancy failure had a median of 22 days post‐insemination. In this test, the model was run using limited inputs, the potential benefits of including additional non‐progesterone information were not evaluated. Despite this, the model performed at least as well as other oestrus detection systems.
Genetic Aspects of Reproduction in Sheep
Authors: Notter DR
Published: July 2008

Contents

Maintenance of high levels of realized fertility (defined as the percentage of ewes that lamb) and appropriate levels of fecundity are critical for efficient sheep production. The optimal level of fecundity in most situations is well below the maximum attainable level and can be targeted by combining selection among and within breeds with use of an expanding array of single‐gene mutations affecting ovulation rate and litter size. The heritability of litter size is approximately 0.10, allowing changes of up to 2%/year from simple mass selection. Mutations in several genes associated with the transforming growth factor β superfamily (BMPRIB, GDF9 and sex‐linked BMP15) can increase ovulation rates by 0.7–1.5 ova in heterozygous ewes. However, ewes that are homozygous for BMP15 or GDF9 mutations are sterile, so use of these mutations requires carefully structured breeding programmes. Improvements in fertility may be critical for autumn lambing or programmes that aspire to lamb throughout the year. Selection to improve fertility in spring matings has been successful; selected adult ewes have lambing rates of 80–85% in October and early November. The selected ewes have a dramatically reduced seasonal anestrus, and many ewes continue to cycle during spring and summer. Major genes affecting seasonal breeding have not been identified in sheep. Polymorphisms in the melatonin receptor 1a gene appear to be associated with seasonal breeding in some, but not all breeds. However, functional genomic studies of genes associated with circadian and circannual rhythms have potential to reveal additional candidate genes involved in seasonal breeding.
Updates on Reproductive Physiology, Genital Diseases and Artificial Insemination in the Domestic Cat
Authors: Axnér E
Published: July 2008

Contents

Reproduction in the domestic cat is characterized by large individual variations in the female oestrous cycle and in male semen quality. The female cat reproduction is strongly influenced by season, and new data suggest that it is possible that season also affects male fertility. Repeated periods of oestrus and spontaneous ovulation may lead to degenerative endometrial changes causing infertility. For artificial insemination (AI), induction of ovulation is necessary in the absence of the mating stimuli. The large variation in the relationship between follicular growth and timing of expression of oestrus complicates, however, timing of ovulation induction. Stress may lead to progesterone secretion by the adrenal glands and possibly have a negative impact on early pregnancy. The large individual variation in semen quality makes fertility evaluation and feline semen conservation a challenge. For AI, the semen can be deposited in the cranial vagina, the uterus or in the uterine tubes. Intrauterine insemination results in higher pregnancy rates than intravaginal but is more complicated. Surgical intrauterine or intratubal insemination has resulted in the birth of kittens, but is an invasive procedure that is not allowed in all countries. Transcervical intrauterine insemination with frozen‐thawed semen has, however, recently resulted in the birth of kittens.
Reproduction of the Female Ferret (Mustela putorius furo)
Authors: Lindeberg H
Published: July 2008

Contents

The domestic ferret is a seasonally polyoestrous species. Females reach puberty at the age of 8–12 months. Females exhibit a constant oestrus between late March and early August if they are not bred. Increasing tumescence in the pink‐coloured vulva is a sign of pro‐oestrus. Oestrus can persist for up to 5 months, but once ovulation is induced, either pregnancy or pseudopregnancy ensues. Follicular development and atresia overlap in such a manner that there is a recent cohort of follicles available for ovulation whenever copulation might occur. Copulation may last from 15 min to 3 h, the average being 1 h. Ovulation is induced by pressure on the cervix associated with copulation. After sufficient LH release, the pre‐ovulatory follicles mature and an average of 12 oocytes (5–13) per female are ovulated 30–40 h after copulation into the ovarian bursa. The ferret oocytes are most capable of being fertilized up to 12 h after ovulation, i.e. 42–52 h after copulation. Ferret oocytes ovulate at the metaphase of the second meiotic division (MII) embedded in three layers of corona radiata cells. Embryos enter the uterus over a period of several days starting on day 5 after mating. Between days 12 and 13 after mating, the embryos have become implanted in the endometrium. Implantation in the ferret is central with rapid invasion of the uterine epithelium by the trophoblast over a broad area that eventually becomes a zonary band of endotheliochorial placenta. Gestation length is 41 days (39–42 days). The domestic ferret gives birth to an average of eight kits (1–18 kits), which weigh 6–12 g at birth.
Physiology of the Canine Anoestrus and Methods for Manipulation of Its Length
Authors: De Gier J. , Beijerink NJ , Kooistra HS , Okkens AC
Published: July 2008

Contents

Progression from early to late anoestrus is characterized by the appearance of a larger number of gonadotrophin‐releasing hormone (GnRH) pulses with a higher amplitude, an increase in the sensitivity of the pituitary to GnRH, an increase in ovarian responsiveness to gonadotrophins, and an increase in basal plasma follicle‐stimulating hormone (FSH) concentration. A period of increased luteinizing hormone (LH) pulsatility has been observed shortly before the onset of pro‐oestrus. Apart from these changes in the hypothalamus‐pituitary‐ovary axis, the initiation of a new follicular phase in the bitch is also stimulated by dopaminergic influences other than the accompanying plasma prolactin decrease. Metergoline, a drug which in a low dosage lowers the plasma prolactin concentration via a serotonin‐antagonistic pathway, does not shorten the anoestrus; while bromocriptine, in a dosage insufficient to cause a decrease in the plasma prolactin concentration, does prematurely induce a follicular phase. These observations indicate that it is not the decrease in the plasma prolactin concentration, but another dopamine‐agonistic influence that plays a crucial role in the transition to a new follicular phase. The dopamine‐agonist induced oestrus is associated with a rapid rise in the basal plasma FSH concentration, similar to what is observed during the physiological late anoestrus. Administration of GnRH, eCG and oestrogens may also be used to induce oestrus but with variable results. Oestrus can be prevented surgically or medically, for which purpose progestagens are the most important drugs. The mechanism is still unclear, although it has been demonstrated that with continuing medroxyprogesterone acetate (MPA) treatment the FSH response to GnRH stimulation decreases and changes occur in the pulsatile release of the gonadotrophins. In general, LH pulses coincide with a FSH pulse, but during MPA treatment, LH pulses were observed while there was such a small increase in FSH that it was not recognized as significant FSH pulse.
Basic Aspects of the Control of GnRH and LH Secretions by Kisspeptin: Potential Applications for Better Control of Fertility in Females
Authors: Caraty A , Franceschini I
Published: July 2008

Contents

The neuronal control of fertility and sterility has been a subject of research for years. However, nowadays, in spite of considerable literature about GnRH during the last few decades, the precise cellular and molecular mechanisms whereby gonadal steroids and other peripheral signals converge in the brain to achieve the fine regulation of GnRH secretion remains partially unknown. In this scenario, a major breakthrough in our understanding of the neuronal signals governing reproduction took place in 2003 with the discovery of metastin/kisspeptin as a major player in the control of GnRH secretion. This molecule, first described as having a crucial role in triggering the onset of puberty, is involved in all phases of reproductive life and hence has attracted the interest of many reproductive neuroendocrinologists. Administered either centrally or peripherally, kisspeptin strongly induces the secretion of gonadotropin in many species, mainly through stimulation of GnRH secretion. Kisspeptin cells involved in the control of GnRH secretion are located in two regions of the brain: the preoptic area and the arcuate nucleus. Carrying oestradiol receptor alpha, kisspeptin cells of these regions appear to be the main integration centres for the expression of both the positive and negative feedback of steroid on GnRH secretion. More recently, this molecule has been shown to be able to synchronize preovulatory surges in cyclic ewes and cause ovulation in seasonally acyclic ewes. This review summarizes the most relevant aspects of the role of kisspeptin in GnRH/LH release and the potential application of this molecule in new strategies for controlling female fertility.
The Expanding Role of Recombinant Gonadotropins in Assisted Reproduction
Authors: Adams TE , Boime I
Published: July 2008

Contents

Using recombinant gonadotropins for assisted reproduction of domestic species is still in its infancy. Yet, the purity, potency and pathogen‐free nature of recombinant gonadotropins make them attractive alternatives to tissue‐derived gonadotropic agents. In this study, the authors summarize the work to date using recombinant gonadotropins to enhance the ‐ fertility of domestic animals and they discussed their recent studies examining the biopotency of single chain analogues of human gonadotropins. In these studies, single chain analogues of follicle stimulating hormone (Fcα), chorionic gonadotropin (CGβα) or a gonadotropin construct with dual activity (FcCGβα) were administered to sheep pre‐treated with antisera directed against GnRH. Ovulation was induced 3 days after analogue administration using hCG (1000 IU, iv). Although Fcα or CGβα alone induced only modest oestradiol production during the pre‐hCG period, serum concentrations of oestradiol were markedly increased (p < 0.05) 3 days after administration of FcCGβα or the Fcα + CGβα combination. Final ovarian weight was significantly increased (p < 0.05) in animals receiving Fcα, Fcα + CGβα or FcCGβα. Collectively, these observations demonstrate that the single chain analogues of the human gonadotropins are active in sheep.
Follicle Development in Mares
Authors: Donadeu FX , Pedersen HG
Published: July 2008

Contents

The mare provides a unique experimental model for studying follicle development in monovular species. Development of antral follicles in horses is characterized by the periodic growth of follicular waves which often involve the selection of a single dominant follicle. If properly stimulated, the dominant follicle will complete development and eventually ovulate a fertile oocyte. Regulation of follicular wave emergence and follicle selection involves an interplay between circulating gonadotropins and follicular factors that ensures that individual follicles are properly stimulated to grow (or to regress) at any given stage of follicular wave development. Periodic development of follicular waves continuously occurs during most of post‐natal life in the mare and is influenced by factors such as stage of oestrous cycle, season, pregnancy, age, breed and individual so that different types of follicular waves (minor or major, ovulatory or anovulatory) and different levels of activity within waves may develop under different physiological conditions. Changes in gonadotropin levels and/or in the sensitivity of follicles to circulating gonadotropins seem to account largely for these physiological variations in follicle development.
Embryonic and Early Foetal Losses in Cattle and Other Ruminants
Authors: Diskin MG , Morris DG
Published: July 2008

Contents

Embryo survival is a major factor affecting production and economic efficiency in all systems of ruminant milk and meat production. For heifers, beef and moderate yielding dairy cows, does and camelids it appears that fertilization generally lies between 90% and 100%. In high‐producing dairy cows there is a less substantive body of literature, but it would appear that it is somewhat lower and perhaps more variable. In cattle, the major component of embryo loss occurs before day 16 following breeding with some evidence of greater losses before day 8 in high‐producing dairy cows. In cattle late embryo loss, while numerically much smaller than early embryo mortality loss, nevertheless, causes serious economic losses to producers because it is often too late to rebreed females when they repeat. In multiple ovulating small ruminants, the loss rate is positively related to ovulation rate. Systemic concentrations of progesterone, during both the cycle preceding and following insemination, affect embryo survival rate with evidence that too high or indeed too low a concentration being negatively associated with survival rate. Uterine expression of mRNA for progesterone receptor, oestradiol receptor and retinol‐binding protein appears to be sensitive to changes in peripheral concentrations of progesterone during the first week after artificial insemination. Energy balance and dry matter intake during 4 weeks after calving are critically important in determining conception rate when cows are inseminated at 70–100 days post‐calving. Concentrate supplementation of cows at pasture during the breeding period has minimal effects on conception rates though sudden reductions in dietary intake should be avoided. For all systems of milk production, more balanced breeding strategies with greater emphasis on fertility and feed intake and/or energy balance must be developed. There is sufficient genetic variability within the Holstein breed for fertility traits. Alternative dairy breeds such as the Jersey or Norwegian Red could also be utilized. Genomic technology will not only provide scientists with an improved understanding of the underlying biological processes involved in fertilization and the establishment of pregnancy, but also, in the future, identify genes responsible for improved embryo survival. Its incorporation into breeding objectives would increase the rate of genetic progress for embryo survival.
Epigenetic Programming of Porcine Endometrial Function and the Lactocrine Hypothesis
Authors: Bartol FF , Wiley AA , Bagnell CA
Published: July 2008

Contents

Epigenetic programs controlling development of the female reproductive tract (FRT) are influenced by the effects of naturally occurring bioactive agents on patterns of gene expression in FRT tissues during organizationally critical periods of foetal and perinatal life. Aberrations in such important cellular and molecular events, as may occur with exposure to natural or manmade steroid or peptide receptor‐modulating agents, disrupt the developmental program and can change the developmental trajectory of FRT tissues, including the endometrium, with lasting consequences. In the pig, as in other mammals, maternal programming of FRT development begins pre‐natally and is completed post‐natally, when maternal effects on development can be communicated via signals transmitted in milk. Studies involving relaxin (RLX), a prototypic milk‐borne morphoregulatory factor (MbF), serve as the basis for ongoing efforts to identify maternal programming events that affect uterine and cervical tissues in the neonatal pig. Data support the lactocrine hypothesis for delivery of MbFs to neonates as a specific consequence of nursing. Components of a maternally driven lactocrine mechanism for RLX‐mediated signalling in neonatal FRT tissues, including evidence that milk‐borne RLX is delivered into the neonatal circulation where it can act on RLX receptor (RXFP1) ‐positive neonatal tissues to affect their development, are in place in the pig. The fact that all newborn mammals drink milk extends the timeframe of maternal influence on neonatal development across many species. Thus, lactocrine transmission of milk‐borne developmental signals is an element of the maternal epigenetic programming equation that deserves further study.
Sexual Maturation in the Bull
Authors: Rawlings N , Evans ACO , Chandolia RK , Bagu ET
Published: July 2008

Contents

In this review, we describe the process of sexual maturation in the bull calf. The testes of the bull grow relatively slowly until approximately 25 weeks of age and then a rapid phase of growth occurs until puberty, at 37–50 weeks of age. During the early postnatal phase of slower growth of the testis pre‐spermatogonia and some spermatogonia are established, adult Leydig cells appear and undifferentiated Sertoli cells are produced. The rapid testicular growth, after 25 weeks of age, consists of marked increases in the diameter and length of the seminiferous tubules, dramatic proliferation and differentiation of germ cells, with mature spermatozoa occurring between 32 and 40 weeks of age. The adult Leydig cell population is largely in place by 30 weeks of age and that of Sertoli cells by 30–40 weeks of age. Serum concentrations of LH increase from 4 to 5 weeks of age, to an early postnatal peak at 12–16 weeks of age, followed by a decline to 25 weeks of age. Serum FSH concentrations are high postnatally, declining to approximately 25 weeks of age. Serum testosterone concentrations increase during the phase of rapid testicular growth. Hypothalamic opioidergic inhibition may abate transiently to allow the early postnatal increase in LH secretion, while testicular androgenic negative feedback probably contributes to the decline in gonadotropin secretion to 25 weeks of age. Several lines of study have led us to suggest that early postnatal gonadotropin secretion is pivotal in initiating the process of sexual maturation in the bull calf.
Epigenetic Regulation of Foetal Development in Nuclear Transfer Animal Models
Authors: Dinnyes A , Tian XC , Yang X
Published: July 2008

Contents

Somatic cell nuclear transfer (SCNT, ‘cloning’) holds great potential for agricultural applications, generation of medical model animals, transgenic farm animals or by ‘therapeutic cloning’ for generating human embryonic stem cells for the treatment of human diseases. However, the low survival rate of SCNT‐derived pregnancies represents a serious limitation of the current technology. In order to overcome this hurdle, a deeper understanding of the epigenetic reprogramming of the somatic cell nuclei and its effect on the pregnancy is needed. Here we review the literature on nuclear reprogramming by SCNT, including studies of gene expression, DNA methylation, chromatin remodelling, genomic imprinting and X chromosome inactivation. Reprogramming of genes expressed in the inner cell mass, from which the body of the foetus is formed, seems to be highly efficient. Defects in the extra‐embryonic tissues are probably the major cause of the low success rate of reproductive cloning. Methods to partially overcome such problems exist, yet more future research is needed to find practical and efficient methods to remedy this problem. Improvement of the survival of foetuses is a central issue for the future of agricultural SCNT not only for its economic viability, but also because in lack of improvements in animal welfare current regulations can block the use of the method in the EU and several other countries.
A Proposed Role for VEGF Isoforms in Sex‐Specific Vasculature Development in the Gonad
Authors: Bott RC , Clopton DT , Cupp AS
Published: July 2008

Contents

Many scientists have expended efforts to determine what regulates development of an indifferent gonad into either a testis or ovary. Expression of Sry and upregulation of Sox9 are factors that initiate formation of the testis‐specific pathway to allow for both sex‐specific vasculature and seminiferous cord formation. Migration of mesonephric precursors of peritubular myoid cells and endothelial cells into the differentiating testis is a critical step in formation of both of these structures. Furthermore, these events appear to be initiated downstream from Sry expression. Sertoli cell secretion of growth factors acts to attract these mesonephric cells. One hypothesis is that a growth factor specific for these cell linages act in concert to coordinate migration of both peritubular and endothelial cells. A second hypothesis is that several growth factors stimulate migration and differentiation of mesonephric ‘stem‐like’ cells to result in migration and differentiation into several different cell lineages. While the specific mechanism is unclear, several growth factors have been implicated in the initiation of mesonephric cell migration. This review will focus on the proposed mechanisms of a growth factor, Vascular Endothelial Growth Factor, and how different angiogenic and inhibitory isoforms from this single gene may aid in development of testis‐specific vascular development.
Application and Commercialization of Flow Cytometrically Sex‐Sorted Semen
Authors: Rath D , Johnson LA
Published: July 2008

Contents

The current technology to sort X and Y chromosome bearing sperm population requires individual identification and selection of spermatozoa in a modified high‐speed flow cytometer. For farm animal species, the technology is capable of producing sexed sperm at greater than 90% purity. However, only in the bovine, the technology has reached a developmental level that allows its commercial application. Meanwhile, the demand for female calves has grown rapidly, which encourages the demand for sex‐sorted semen from high genetic value bulls. The success of the technology will depend mainly on the fertilizing capacity of the sorted spermatozoa, as this is the most affecting and economically relevant factor. To date, fertility is still variable and is quite dependant on post‐sort processing. New processing techniques are under investigation and will likely be able to improve the fertility rates after AI with sex‐sorted semen. It is of great importance to select the right bulls and to test the sorted samples on a routine basis. In addition to the demand for sex‐sorted semen by the cattle industry, there is also a significant demand expressed by pig farmers. However, it is still unknown if the use of sex‐sorted semen through commercial pig AI will be economically feasible. For the pig, the combination of in vitro fertilization with sexed semen and non‐surgical embryo transfer is an alternative that merits further scientific attention. Recent developments in ovine AI and ET will make it very likely that commercial sheep industry will adopt the sexing technology in their breeding concepts.
Low‐Dose Insemination in Pigs: Problems and Possibilities
Authors: Vazquez JM , Roca J , Gil MA , Cuello C , Parrilla I , Caballero I , Vazquez JL , Martínez EA
Published: July 2008

Contents

Low‐dose AI procedures are required by the pig industry to efficiently utilize emerging sperm technologies, such as cryopreservation and sex‐sorting. Currently, several different procedures for inseminating with a low or very low number of spermatozoa have been described. Deep intrauterine insemination allows the deposition of the spermatozoa in the depth of the uterine horn, allowing a significant reduction in the number of spermatozoa inseminated with maintenance of optimal reproductive performance. Intra‐oviductal laparoscopic insemination has been recently applied in pigs. This technique has proved to be applicable with diluted and sex‐sorted spermatozoa. This review discusses several problems encountered during the development of deep intrauterine insemination and intra‐oviductal laparoscopic insemination of pigs and provides potential solutions for the practical application of both the technologies.
Production of Transgenic Farm Animals by Viral Vector‐Mediated Gene Transfer
Authors: Whitelaw CBA , Lillico SG , King T
Published: July 2008

Contents

Transgenic technology holds considerable promise to advance understanding in biomedical and agricultural systems with some believing that one day transgenic animals may directly contribute to farming and breeding practice. Nevertheless, applications in livestock have been restricted in part by the inefficiency of the technology. The recent development of lentivirus vectors for transgene delivery may overcome some of this limitation. This presentation describes these vectors, their advantages and limitations.
Use of Microarray Technology to Profile Gene Expression Patterns Important for Reproduction in Cattle
Authors: Evans ACO , Forde N , O’Gorman GM , Zielak AE , Lonergan P , Fair T
Published: July 2008

Contents

Fertility in cattle is a major component of many agricultural enterprises and there is pressure to devise methods to improve this. A number of approaches are ongoing, one of which is to better understand the cellular and molecular events of the development of reproductive tissues and to use these as targets for developing new strategies. Microarray technologies now allow us the potential to determine the transcriptional profile of expressed genes in a given tissue. This review focuses on the types of microarrays available for studies in cattle and concludes that genes associated with one or more of the cellular processes of cell survival/death, intracellular signalling, transcription and translation, cell division and proliferation and cellular metabolism are the main transcriptional pathways that control the development of ovarian follicles, oocytes, early embryos and the uterine endometrium about the time of the establishment of pregnancy.
Management of Goat Reproduction and Insemination for Genetic Improvement in France
Authors: Leboeuf B , Delgadillo JA , Manfredi E , Piacère A , Clément V , Martin P. , Pellicer M , Boué P , De Cremoux R
Published: July 2008

Contents

Reproductive seasonality observed in all breeds of goats originating from temperate latitudes and in some breeds from subtropical latitudes can now be controlled by artificial changes in photoperiod. Short days stimulate sexual activity, while long days inhibit it. This knowledge has allowed the development of photoperiodic treatments to control sexual activity in goats, for both the buck and doe. In the French intensive milk production system, goat AI plays an important role to control reproduction and, in conjunction with progeny testing, to improve milk production. Most dairy goats are inseminated out of the breeding season with deep frozen semen, after induction of oestrus and ovulation by hormonal treatments. This protocol provides a kidding rate of approximately 65%. New breeding strategies have been developed, based on the buck effect associated with AI, to reduce the use of hormones. With the development of insemination with frozen semen, a classical selection programme was set up, including planned mating, progeny testing and the diffusion of proved sires by inseminations in herds. Functional traits have become important for efficient breeding schemes in the dairy goat industries. Based on knowledge gained over the past decade, the emphasis in selective breeding has been placed on functional traits related to udder morphology and health. New windows have been opened based on new molecular tools, allowing the detection and mapping of genes of economic importance.
Climbing Mount Efficiency – Small Steps, Not Giant Leaps Towards Higher Cloning Success in Farm Animals
Authors: Oback Björn
Published: July 2008

Contents

Despite more than a decade of research efforts, farm animal cloning by somatic cell nuclear transfer (SCNT) is still frustratingly inefficient. Inefficiency manifests itself at different levels, which are currently not well integrated. At the molecular level, it leads to widespread genetic, epigenetic and transcriptional aberrations in cloned embryos. At the organismal level, these genome‐wide abnormalities compromise development of cloned foetuses and offspring. Specific molecular defects need to be causally linked to specific cloned phenotypes, in order to design specific treatments to correct them. Cloning efficiency depends on the ability of the nuclear donor cell to be fully reprogrammed into an embryonic state and the ability of the enucleated recipient cell to carry out the reprogramming reactions. It has been postulated that reprogrammability of the somatic donor cell epigenome is influenced by its differentiation status. However, direct comparisons between cells of divergent differentiation status within several somatic lineages have found no conclusive evidence for this. Choosing somatic stem cells as donors has not improved cloning efficiency, indicating that donor cell type may be less critical for cloning success. Different recipient cells, on the otherhand, vary in their reprogramming ability. In bovine, using zygotes instead of oocytes has increased cloning success. Other improvements in livestock cloning efficiency include better coordinating donor cell type with cell cycle stage and aggregating cloned embryos. In the future, it will be important to demonstrate if these small increases at every step are cumulative, adding up to an integrated cloning protocol with greatly improved efficiency.
Nuclear Transfer of Freeze‐Dried Somatic Cells into Enucleated Sheep Oocytes
Authors: Loi P , Matzukawa K , Ptak G , Natan Y , Fulka Jr J , Arav A
Published: July 2008

Contents

Lyophilization has been used since long time to preserve yeast and bacteria strains. Subsequently, a great deal of efforts has been dedicated to the preservation in a dry state of red blood cells and platelets. However, despite more than 30 years passed by, no significant progress has been achieved. Recently, it has been reported that freeze‐dried mice spermatozoa were able to generate normal offspring following injection into the mature mice oocytes. In this work, we prompted to apply the lyophilization protocol developed for mice spermatozoa to sheep somatic cells (lymphocytes and granulosa cells). More than 350 enucleated sheep oocytes were injected with granulosa cells, and freeze dried using the protocol developed for mice sperm cells. Transplanted nuclei organized large pronuclei with fragmented DNA, but none of them entered the first mitosis. In the second part of the experiments, trehalose and EGTA were found to reduce significantly the extent of nuclear damage (65% and 55% intact nuclei in lymphocyte and granulosa cells, respectively) following freeze drying. Granulosa cells lyophilized with EGTA/trehalose and stored at room temperature for 3 years were used for nuclear transfer, and the injected oocytes were cultured in vitro for 7 days. Approximately 16% of the oocyte injected with freeze‐dried cells developed into blastocysts. To conclude, we demonstrated for the first time that nucleated cells maintain genomic integrity after prolonged storage in a dry state, and we were able to achieve early embryonic development following injection of these cells into enucleated sheep oocytes.
Ocular adnexal IgG4‐related disease has uniform clinicopathology
Authors: Sato Yasuharu , Ohshima Koh‐ichi , Ichimura Kouichi , Sato Masakazu , Yamadori Ichiro , Tanaka Takehiro , Takata Katsuyoshi , Morito Toshiaki , Kondo Eisaku , Yoshino Tadashi
Published: July 2008

IgG4‐related disease is a recently proposed clinical entity with several unique clinicopathological features. Ocular adnexal IgG4‐related disease, however, has not well been clarified. The purpose of the present study was to examine 21 patients (10 men, 11 women; age range, 39–86 years) with ocular adnexal IgG4‐related disease. In 17 out of 21 patients (81%), the lacrimal glands were involved and bilateral lacrimal gland swelling was frequently observed (n = 12; 70.6%). In contrast, the conjunctiva was not involved in any of the patient. Histology was uniform with marked lymphoplasmacytic infiltration admixed with dense fibrosis, similar to previous reports of IgG4‐related disease. Immunostaining detected numerous aggregates of IgG4‐positive plasma cells. Serum IgG4 was higher than normal in 10 of the 13 patients tested, although it was measured after treatment in almost all cases. Interestingly, immunoglobulin heavy chain gene rearrangement was detected in two of 17 patients (12%) examined. The present results show that ocular adnexal IgG4‐related disease has uniform clinicopathology: that is, disease involving the bilateral lacrimal glands with lymphoid hyperplasia and fibrosis, but not the conjunctiva. And presence of immunoglobulin heavy chain gene rearrangement suggests the possibility of B‐cell lymphoma arising in a background of IgG4‐related chronic inflammation.
Sebaceous carcinoma of the eyelids: Thirty cases from Japan
Authors: Izumi Miki , Mukai Kiyoshi , Nagai Takeshi , Matsubayashi Jun , Iwaya Keiichi , Chiu Cheng‐Sheng , Goto Hiroshi
Published: July 2008

Sebaceous carcinoma of the eyelids is rare in Western countries but not uncommon in Asian countries. Diagnosis is difficult both clinically and histologically. Thirty cases of sebaceous carcinoma of the eyelids treated at Tokyo Medical University Hospital were reviewed to elicit characteristic features of pathological findings. The tumor cells were infiltrating in a lobular pattern that consisted mainly of large atypical germinative cells. Sebocytes seen in the lobules had conspicuous nucleolus associated with perinucleolar halo. In 17 cases (57%) there was foamy histiocyte infiltration in and around the tumor nests. Sebaceous duct differentiation, namely holocrine secretion indicating a specific type of coagulation necrosis maintaining a cellular framework or maintaining a bubbly cytoplasm associated with nuclear debris in the periphery, was seen in 24 cases (80%). Although unequivocal squamous differentiation was limited to only 11 carcinomas, scattered individual necrosis with nuclear debris in the background of germinative cells appeared in 29 cases (96.7%). Expression of epithelial membrane antigen, perilipin and adipophilin were detected in all cases. In conclusion, to detect sebaceous differentiation in sebaceous carcinoma, it would be helpful to focus on holocrine secretion, squamous differentiation and foamy macrophage infiltration, and to utilize immunohistochemistry involving anti‐perilipin and anti‐adipophilin stain.
Small cell variant of anaplastic large cell lymphoma diagnosed by a novel chromosomal abnormality t(2;5;3)(p23;q35;p21) of bone marrow cells
Authors: Sano Fuminori , Tasaka Taizo , Nishimura Hirotake , Akiyama Takashi , Kubo Yasutaka , Matsuhashi Yoshiko , Wada Hideho , Sugihara Takashi , Sadahira Yoshito
Published: July 2008

Because of the rarity and the morphological variations, small cell variant of anaplastic large cell lymphoma (ALCL) represents a diagnostic challenge. Herein is reported a case of leukemic type of small cell variant of ALCL, in which the diagnosis was established by a cytogenetic analysis. The patient was a 23‐year‐old woman who presented with fever and leukocytosis with circulatory atypical lymphoid cells. The initial differential diagnosis on bone marrow trephine biopsy sections included viral infection and peripheral T‐cell lymphoma unspecified. But a cytogenetic study on bone marrow cells indicated a novel complex translocation, t(2;5;3)(p23;q35;p21), which led to confirmation of anaplastic lymphoma kinase (ALK)‐positive pleomorphic small to medium‐sized cells scattered in bone marrow cells, on immunohistochemistry. ALK was distributed in both nuclear and cytoplasmic regions of neoplastic cells. The patient achieved complete remission after four courses of combination chemotherapy, and received autologous peripheral stem cell transplantation (auto‐PBSCT) after two additional courses of combination chemotherapy, but relapsed 2 months after auto‐PBSCT in the bilateral lung. Allogeneic stem cell transplantation led to a second remission. This case demonstrates the diagnostic importance of cytogenetic study for malignant lymphoma involving bone marrow.
Cholangiocarcinoma arising in von Meyenburg complexes: Report of four cases
Authors: Song Joon Seon , Lee Young‐Joo , Kim Kyoung Won , Huh Jooryung , Jang Se Jin , Yu Eunsil
Published: July 2008

Although von Meyenburg complexes (VMC) are largely considered to be innocuous, neoplastic transformations have been described. The present report describes four cases of cholangiocarcinoma (CC) occurring on a background of VMC. The patients were all male and aged 69, 59, 68 and 75 years, respectively. While two patients were asymptomatic, the other two had a history of colon cancer. Radiologically the tumors measured 3, 4, 4.5 and 10 cm and were well enhanced from the arterial to delayed portal phase. Microscopically, the tumor consisted of multiple foci of characteristic VMC, and had a gradual transition from VMC to hyperplasia or dysplasia and well‐ to moderately differentiated adenocarcinomas. One patient had combined hepatocellular carcinoma (HCC) and CC, occurring in the high grade dysplastic nodule and VMC. On immunohistochemistry the epithelial cells of the VMC and CC were immunopositive for cytokeratin (CK) 7 in three patients, with another patient being focally positive only for CK19. The Ki‐67 labeling indices increased from the VMC to the dysplastic areas and then to the carcinomas. As a potentially precancerous lesion, VMC should be carefully followed up in terms of any size increases. Thus, biopsies are essential to determine any proliferative epithelial changes including dysplasia and malignant transformation.
Cystadenoma of the palate: Immunohistochemistry of mucins
Authors: Kusafuka Kimihide , Ueno Takao , Kurihara Kinue , Murata Tsubasa , Yurikusa Takashi , Henmi Hitoshi , Akane Mitsunori , Ota Yojiro , Kameya Toru
Published: July 2008

Cystadenoma is a relatively rare benign epithelial tumor of the salivary glands, and described herein is an additional case. A 51‐year‐old Japanese man had noticed a mass of the left hard palate 25 years previously. Macroscopically, the resected specimen was a multicystic lesion. Histologically, the tumor was composed of bilayered columnar epithelium with cystic change and partial solid growth of glandular structures with clear cells. The tumor cells had mild cellular atypia, but the tumor lacked papillary growth and a fibrous capsule. Immunohistochemistry was positive for cytokeratins, epithelial membrane antigen, MUC1, MUC4 and MUC6, but negative for myoepithelial markers, MUC2, MUC5AC and MUC5B. Such MUC expression patterns suggested that cystadenoma occurs from excretory ducts.