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From Embryology

Lab Attendance

Lab 1 --Z3415716 (talk) 12:52, 6 August 2014 (EST)

http://www.ncbi.nlm.nih.gov/pubmed

PubMed

PMID25084016

<pubmed>25084016</pubmed> Lab 2 --Z3415716 (talk) 11:13, 13 August 2014 (EST)

Lab 3 --Z3415716 (talk) 12:54, 20 August 2014 (EST)

Lab 4--Z3415716 (talk) 12:27, 27 August 2014 (EST)

Lab 5 --Z3415716 (talk) 12:56, 3 September 2014 (EST)

Lab 6 --Z3415716 (talk) 12:37, 10 September 2014 (EST)

Lab 8 --Z3415716 (talk) 12:57, 24 September 2014 (EST)

Assessment Lab 1

Article 1

Effect of Vitamin D status on clinical pregnancy rates following in vitro fertilisation

The study undertaken by Garbedian et al. attempted to investigate whether vitamin D (25-hydroxy-vitamin D) serum level of in vitro patients could predict the successfulness of in vitro fertilisation (IVF). 173 patients participated, having met the criteria of age (18-41 years), follicle-stimulating hormone level (≤12IU/L at day 3 of the menstrual cycle), and consent.

Serum samples were collected from the participating women, prior to oocyte retrieval, and were analysed, dividing the patients into two groups, sufficient (≥75 nmol/L) or insufficient (<75 nmol/L), based on their serum vitamin D levels. Regardless of this division, the IVF procedures were undertaken as per standard protocol.

This article focused on two main outcomes, embryo implantation, and clinical pregnancy. Implantation was described as the establishment of a gestational sac upon ultrasonography screening. Whereas clinical pregnancy assessed via ultrasound, was determined by the visibility of an intrauterine sac. The results were collated, analysed, and compared between the groups in order to discover a relationship, if any, between serum vitamin D levels and both implantation and clinical pregnancy rates.

Garbedian and colleagues found significant differences between the groups’ rate of embryo transfer and clinical pregnancy, however this is not the case in implantation rate. In consistency with the IVF protocols, embryo transfer was to take place on day 5, if at least 5-6 acceptable embryos were developed by day 3 of fertilisation. It was discovered that women with a sufficient level of serum vitamin D were more likely to achieve this step by day 5 than women with low serum vitamin D. Moreover, a higher clinical pregnancy rate was observed within the same group of women. An increased value of embryo implantation rate was noted, however results were statistically insignificant.

With acknowledgement of the study’s limitations, Garbedian et al. concluded that women sufficient in vitamin D serum levels were more likely to achieve clinical pregnancy following IVF, with serum levels of the vitamin acting as an independent predictor.

Effect of vitamin D status on clinical pregnancy rates following in vitro fertilization.

<pubmed>25077107</pubmed>

Article 2

The Role of SPRASA in Female Fertility

Sperm protein reactive with antisperm antibodies (SPRASA) also referred to as sperm lysosome-like protein 1 is a target protein of antisperm antibodies, and is the key protein explored within the article by Wagner et al. Numerous tests were preformed within this study investigating the role of this protein, particularly in fertilisation and embryonic development.

The Bovine IVF model was employed to determine the effect of SPRASA antiserum on fertilisation, cleavage, and embryo development. Both bovine zona pellucida-attached and zona pellucida-free oocyte-sperm binding was investigated with the presence of antiserum preparation. Wagner and colleagues were able to conclude that fertility rates significantly reduced when SPRASA antiserum was added to oocytes, and sperm and oocytes samples, but not to sperm samples alone. Further on this note, the study found that the antiserum preparation negatively influenced the zona pellucida-free oocyte (oolemma)-sperm binding process, whereas no significant effect was found in the zona pellucida-attached oocyte-sperm binding. In terms of development, it was discovered that the antiserum was able to inhibit morula stage growth but not the further development at the blastocyst stage.

Wagner and colleagues also assessed the influence on sperm motility by SPRASA and observed that sperm motility was not an affected area as there was no significant difference between motile sperm in antiserum perpetration and the control group.

As previously thought that SPRASA was only present in spermatozoa, this study examined whether the protein was also expressed in oocytes and ovaries. Bovine oocytes, and ovaries from cats and dogs, were obtained for this section of the research. Similarly, sperm and sperm precursor cells were collected from testis of cats and dogs in order to illustrate the presence of SPRASA proteins. Results indicated that oocytes express SPRASA and staining was able to localise the protein to the zona pellucida and oolemma of bovine oocytes. Similar preparation and staining was carried out on ovaries of cats and dogs, and returned with positive expression of SPRASA.

Fertilisation and embryo development was tested via immunisation and mating of female mice. Female mice were either continuously immunised with recombinant human SPRASA protein or irrelevant recombinant keyhole limpet hemocyanin (KLH) protein (control). The mice were then monitored, relocated for mating with male mice, and then compared in terms of pregnancy and fetal development. Wagner et al. found that all control mice became pregnant after 2 mating cycles, whereas the majority of SPRASA immunised mice failed to achieve pregnancy altogether. In regards to the number of embryo development and weight, no difference was recorded between the control and immunised mice.

The final test was comparing the antibody levels from blood samples of fertile and infertile couples. Upon analysis of results, Wagner et al. discovered no significant difference between both fertile and infertile men and women, however 3 of the infertile women presented with inflated levels of the antibodies.

Wagner et al. concluded that SPRASA, to a certain extent, plays a role in fertilisation and embryo development. They also rebutted the previous theory that the protein is solely expressed in male gametes with identifying SPRASA within the female reproductive structures.

The Role of SPRASA in Female Fertility.

<pubmed>25038051</pubmed>

Assessment Lab 2

WNT4 screening in the testis of the tammar wallaby


<pubmed>17014734</pubmed>| Biomed Central

--Mark Hill This is fine and description with the image is good. You should have also reproduced the figure description and the reference here on your page. (4/5)

Assessment Lab 3

<pubmed>18462432</pubmed> <pubmed>17232227</pubmed> Martyn P. L. Williams, John M. Huston The history of ideas about testicular descent. Pediatric Surgery International: 1991, 6(3):180-184 The history of ideas about testicular descent

Assessment Lab 4

Article 1

Conversion of human umbilical cord mesenchymal stem cells in Wharton's jelly to dopaminergic neurons in vitro: potential therapeutic application for Parkinsonism

Parkinson’s disease is a neurodegenerative disorder associated with the degradation of the dopaminergic system in the striatum region of the brain. Current short-term treatment for Parkinson’s disease is antiparkinson medications, mainly enhancing dopamine levels, however such medications reduce in effectiveness with further degradation of the neurotransmitter’s pathway. The study led by Fu, however, proposes a potential long-term treatment for Parkinson’s disease, utilising induced human mesenchymal stem cells (HMSCs) originating in the Wharton’s jelly of the umbilical cord.

Fu et al. isolated HMSCs from the umbilical cord exposing the cells to subsequent chemical treatment resulting in the differentiation of these multipotent cells into dopaminergic neurones. These neurones were then injected into the subjects, adults rats with induced Parkinson’s post unilateral striatal lesioning. Subjects were compared with control untreated rats, concluding that the transplanted group exhibited a substantial improvement in rotational behaviour and Parkinson’s symptoms, however not enough to deem them cured from the disease.

The potential for HMSCs, isolated from the umbilical cord, to correct Parkinson’s disease is further emphasised in its easy isolation methods, the large amount of cells able to be isolated, and the simple duplication of these stem cells. Fu et al. were able to collect 1x10^6 HUMSCs from 20 cm of umbilical cord and duplicate the amount to 2x10^6 cells in a three day incubation period. Furthermore, the study found that the transplanted differentiated cells were still successful 4 months post procedure, suggesting that this method may be a long-term treatment for the disease. The investigation also comments on the prospect of HUMSCs as a source for transplantation, attributed to its non-immunological inducing characteristic.

<pubmed>16099997</pubmed>

Vascular shunts

There are three shunts within the foetal circulatory development that close postnatally:

  • Ductus arteriosus


A canal that connects the foetal pulmonary artery to the aorta, distributing oxygenated blood to the foetus while bypassing the developing lungs.

  • Ductus venosus


Connecting the left umbilical vein to the inferior vena cave, allowing placental oxygenated blood to bypass the liver.

  • Foramen ovale


A foramen within the interatrial septum where blood from the right atrium enters the left atrium.

Assessment Lab 5

Oesophageal atresia

Oesophageal atresia is a rare gastrointestinal developmental abnormality, however in terms of oesophageal anomaly it is the most common, with one newborn out of every 2500 to 4500 being diagnosed within the first 24 hours of life [1]. Oesophageal atresia is diagnosed with the discontinuity of the oesophagus from the oral cavity to the stomach, where the oesophagus ends abruptly not in contact with the cardia of the stomach.

Oesophageal atresia can be classified into five variants according to the location of the atresia and any associated tracheal fistulas (tracheoesophageal fistula) [1]. The five classifications include: oesophageal artesia without tracheoesophageal fistula, proximal tracheoesophageal fistula with distal oesophageal atresia, distal tracheoesophageal fistula with proximal oesophageal atresia, proximal and distal tracheoesophageal fistula, and tracheoesophageal fistula without oesophageal atresia [1].

The cause for this gastrointestinal abnormality is unclear and research continues to take place. With that said, various theories of the embryological origin of this anomaly have been proposed [1]. Three forefront theories comment on the primitive digestive tube and its failure to form a successful diverticulum, resulting in the connection of the trachea and oesophagus (tracheoesophageal fistula). In terms of the formation of oesophageal atresia, two of the three theories reason that the cellular distal portion of the primitive digestive tube rearranges and results in an abnormal discontinuous growth; whereas the third theory emphasises that the atresia is a consequence from regression of that portion of the tube towards the main part of the embryo. Currently no genetic roles have been identified in this developmental abnormality [1].

Regardless of the lack of information gathered about the cause of oesophageal atresia, more advanced correctional surgeries have been introduced in the past decade [2]. Survival rates differ immensely between various nations, particularly when comparing developed to developing countries. In certain clinics, with state-of-the-art neonatal care, survival rates of up to 95% has been documented [1]. Surgical methods such as thoracoscopic repair has been improved within the past decade, resulting to a decrease in surgical complications and therefore an increase in survival rates [2].

[1] <pubmed>22851858</pubmed> [2] <pubmed>22584690</pubmed>

Assessment Lab 7

Article 1

Fetal Adrenal Gland in the Second Half of Gestation: Morphometric Assessment with 3.0T Post-Mortem MRI

The adrenal gland, a bilateral organ located immediately superior the kidneys, are part of the endocrine system, playing an important role in releasing certain hormones such as cortisol and adrenaline in response to various situations including stressful situations. It is said that the adrenal gland is crucial in foetal development and that in comparison to other foetal organs, the foetal adrenal gland is relatively large. The study carried out by Zhonghe et al. quantitatively assessed the length, width, height, surface area and volume of normal foetal adrenal glands.

52 foetal specimens ranging from 23-40 gestation weeks old were the subjects of this experiment. 72 foetal specimen were collected based on parental consent and in accordance with the Ethical Committee at the School of Medicine, Shandong University. Out of the 72 only 52 were utilised as foetuses with known abnormal maternal pregnancy records did not meet the criteria. The 52 subjects were organised in terms of their gestational age, found by measuring their crown-rump length via MRI. A highly advanced MRI scanner, SIEMENNS 3.0T MR scanner, was then employed in this research, measuring the adrenal glands of the foetus in the transverse, coronal and sagittal axis. Post-scanning, four specimens (24, 26, 32 and 36 weeks gestation age) were selected for gross anatomy dissection and measurement.

Upon completing the measurements and gross dissections, Zhonghe et al. found that the bilateral organ was asymmetrical, with the right adrenal gland resembling an irregular triangle or pyramid, whereas the shape of the left adrenal gland was closer to a half-moon and larger than its right counterpart. No significant difference was found between the sexes, in contrast to previous research articles, however Zhonghe et al. attributed this discrepancy on it's relatively small group of specimens and uneven distribution of male and female foetuses. It was also discovered that as the gestational age increases the zona glomerulosa (outer zone of the cortex layer) became thicker.

Zhonghe et al. regard their research and results as valuable in clinical settings and useful reference for the foetal anatomy.

<pubmed>24116052</pubmed>

Tooth Development

Odontogenesis begins in the sixth week of development. The embryonic cells/layers that differentiate to form the developing tooth include:

  • Odontoblasts — mesenchymal neural crest originating cells that secrete predentin, which calcifies to form dentin, the inner layer of the tooth. These cells are present throughout life and continuously produce dentin.
  • Ameloblasts — ectodermal cells of the oral epithelium that produce enamel, the outermost layer in the crown part of the tooth. Only present during odontogenesis.
  • Periodontal ligament — a specialised connective tissue that is in contact with the cementum layer (outer layer in the root of the tooth) and holds the tooth within the alveolar process.

Assessment Lab 8

Ovary Development

Embryonic female differentiation and development was once perceived as a passive process, simply by the failure of developing male genital organs, however it is shown that this is not the case, with many molecular and genetic prerequisites required to develop the female genital system. [1]

Identical to the testes, the ovaries originate from the mesothelium, the underlying mesenchyme, and primordial germ cells. Within the early embryo, the gonads consists of a mesonephric duct (Wolffian duct), paramesonephric ducts (Mullerian ducts), and the external cortex and internal medulla regions.

Gonadal development begins in the fifth week, medially to the mesonephros. The first structure of the developing gonad is the gonadal ridge. This ridge is formed by the proliferation of the mesenchyme tissue. The proliferating mesenchyme then grow epithelial cords, known as gonadal cords that extend to the developing ovary later on.

The primordial germ cells, undifferentiated sex cells, become visible by day 24 of the embryonic period. The germ cell is relocated to the gonadal ridges during the folding process of the embryo. In the late embryonic phase, the lack of anti-mullerian hormone and testosterone is what beings the differentiation between the male and female genital development. At this point of time the Wolffian duct degenerates but the Mullerian ducts remain, in contrast to the male gonadal development. It is the Mullerian ducts that develop into the internal genital organs, the upper part into the fallopian tubes, and the lower part into the uterus and the vagina. [2]

During the 10th week, the ovaries become recognisable with the gonadal cords extending into the surface of the ovary. It is within this foetal developmental phase, beginning in the 16th week, that the gonadal cords commence degeneration forming primordial oocytes, referred to as oogonium. These oogonia, surrounded by a thin layer of epithelial cells, are the primordial follicles that a formed by mitosis.

Bailey329.jpg

Transverse section of the ovary of a fox embryo

References

  1. <pubmed>15664455</pubmed>
  2. <pubmed>13230915</pubmed>

Textbook Moore: The Developing Human Chapter 12

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