Guided Studies W9/10 Flashcards
Define hypospadias, explaining the developmental cause of it.
Fusion of the urethral fold is incomplete, and abnormal openings of the urethra occur along the inferior aspect of the penis, usually near the glans, along the shaft, or
near the base of the penis. In rare cases the urethral meatus extends the scrotal raphe. When
fusion of the urethral fold fails entirely, a wide saggital slit is found along the entire length of the penis and the scrotum. The two scrotal swellings then closely resemble the labia major
Define epispadias, explaining the developmental cause of it. Which other genital defect is this associated with ?
Urethral meatus is found on the dorsum of the penis. Instead of developing at the cranial margin of the cloacal membrane, the genital tubercle seems to form in the region of the urorectal septum. Hence a portion of
the cloacal membrane is found cranial to the genital tubercle, and when this membrane ruptures, the outlet of the urogenital sinus comes to lie on the cranial aspect of the penis. Although epispadias may occur as an isolated defect, it is most often associated with exstrophy of the bladder.
Define exstrophy of the bladder, explaining the developmental cause of it.
(epispadias is a constant feature of it)
The bladder mucosa is exposed to the outside. Normally the abdominal wall in front of the bladder is formed by
primitive streak mesoderm, which migrates around the cloacal membrane. When the migration does not occur, rupture of the cloacal membrane extends cranially, creating exstrophy of the bladder.
Identify major congenital genital defects.
Female:
-Duplications of the uterus
Male:
- Hypospadias
- Epispadias
- Exstrophy of the bladder
- Eongenital inguinal hernia
- Hydrocele of the testis and/or spermatic cord
- Cryptochidism
Define duplication of the uterus, explaining the developmental cause of it and identify the main types of this.
Duplications of the uterus result from the lack of fusion of the paramesonephric ducts in a local area or throughout their normal line of fusion. In its extreme form the uterus is entirely double (uterus didelphys); in the least severe form, it is only slightly indented in the middle
(uterus arcuatus). One of the relatively common anomalies is the uterus bicornis, in which the uterus has two horns entering a common vagina.
Define congenital inguinal hernia, explaining the developmental cause of it.
The connection between the abdominal cavity and the processus vaginalis in the scrotal sac
normally closes in the first year after birth. If this passageway remains open, intestinal loops
may descend into the scrotum, causing a congenital inguinal hernia.
Explain how hydroceles of the testes and/or spermatic cord may arise developmentally.
The connection between the abdominal cavity and the processus vaginalis in the scrotal sac
normally closes in the first year after birth. Sometimes obliteration of this passageway is irregular, leaving small cysts along its course. Later these cysts may
secrete fluid, forming a hydrocele of the testis and/or spermatic cord.
What is the main cause of cryptorchidism ?
May be caused by decreased androgen (testosterone) production
Outline how CRISPR can edit DNA.
”
1) Clustered regularly interspaced short palindromic repeats, or CRISPRs, are repeating sequences found in the genetic code of bacteria. They are interspersed with ‘spacers’ — unique stretches of DNA that the bacteria grab from invading viruses, creating a genetic record of their malicious encounters.
2) On a repeat encounter with a virus, a bacterium can produce a stretch of RNA that matches the viral sequence, using the material in its spacer archive. This ‘guide RNA’ teams up with DNA-cutting Cas enzymes, encoded by nearby CRISPR-associated genes, to seek out and ‘cleave’ the matching viral sequences, stopping the virus from replicating.
3) By engineering the guide RNA, researchers can programme Cas enzymes — most commonly Cas9 — to match the DNA at specific sites that they want to cut in a cell’s genome. This triggers a DNA repair that can result in precise sequence changes to the gene of interest.”
Discuss 7 separate ethical concerns around the introduction of genome editing.
♦ Non-maleficence: If policymakers do not consult people with disabilities and their families, the technology could be used unthinkingly, in ways that harm patients and society, today and in the future.
♦ Non-maleficence: Mutations that predispose to genetic disease, such as the sickle-cell mutation, confer population-level benefits, such as resistance to malaria. So editing out one disease could backfire by increasing the risk of another. She argues that very little is known about the potential benefits of other mutations associated with disease, and applying genome editing too freely could have unintended consequences.
♦ Slippery slope: Many people are concerned about where that line would be drawn. Although it may seem now that only a few, very severe conditions should be subject to gene editing, disability activists point out that the list of conditions considered as illnesses, and possibly subject to medical treatment, is expanding (e.g. obesity, predispoition to alcoholism)
♦ Beneficence: Accommodations originally intended for people with disabilities often end up benefiting everyone. For example, the development of closed captioning — subtitles for the hearing-impaired on television. Similarly, legislative mandates, such as the 1990 Americans with Disabilities Act in the United States, have helped to integrate people with disabilities into society — in workplaces, schools and other public spaces. As a result, the world is much more humane for everyone The idea that parents should edit out characteristics that are considered debilitating goes against this drive towards inclusion, Garland-Thomson warns, and could create a harsher social climate for everyone. The experience of disability, she adds, is universal; all people inevitably experience sickness, accidents and age-related decline. “At our peril, we are right now trying to decide what ways of being in the world ought to be eliminated
♦ Beneficence: People without disabilities consistently underestimate the life satisfaction of those with them. Although people with disabilities report a slightly lower overall quality of life than those without, the difference is small. One study3 found that half of people with serious disabilities ranked their quality of life as ‘good’ or ‘excellent’. People also overestimate how severely health affects their happiness compared with other factors, such as economic or social support.
♦ Autonomy: Pressure exists to make women who carry a child with an abnormality (e.g. Down’s Syndrome) terminate their pregnancy. This is troubling and that it could get worse if embryo editing were to become readily available. “Women should not be given the responsibility of ensuring the genetic fitness of their children based on lack of support for children with disabilities.”
♦ Inequality: And if it were adopted, the technology would almost certainly be applied unevenly around the world. Aleksa Owen, a sociologist at the University of Illinois at Chicago, predicts that genome editing would be used first in countries that approve of and support assisted reproductive technologies, such as the United Kingdom, some other European Union countries, China and Israel. But it would probably be too expensive for many people in developing countries.
Describe the histological appearance of small follicles.
Small follicles = primordial follicles
They consist of a large oocyte surrounded by a layer of flattened follicular cells (refer to http://141.214.65.171/Histology/Female%20Reproductive%20System/239_HISTO_40X.svs/view.apml?X=0.0679240044988367&Y=-0.0432043349683487&zoom=75)
Describe the histological appearance of medium follicles.
Medium follicles = primary follicles
Large oocyte is surrounded by a layer of cuboidal follicular cells. These follicular cells proliferate to form a loose multi-layer, the granulosa cell layer. A rim of neutral glycoprotein, the zona pellucida (clear zone), surrounds the oocyte separating it from the surrounding granulosa cells (refer to http://141.214.65.171/Histology/Female%20Reproductive%20System/239_HISTO_40X.svs/view.apml?X=0.234444232680326&Y=0.350062709638043&zoom=75)
Describe the histological appearance of large follicles.
Large follicles = pre-ovulatory follicles
With continued development, the follicle becomes a Graafian or ovulatory follicle. The granulosa zone now consists of many layers of cuboidal follicular epithelial cells located at the periphery of the large, well-formed follicular antrum. The oocyte has attained its full size, is located eccentrically within the follicle in a small hillock, the cumulus oophorus which protrudes into the antrum. The zona pellucida is surrounded by a continuous layer of follicular cells, the corona radiata. The theca interna is separated from the granulosa cells by a distinct basement membrane (refer to http://141.214.65.171/Histology/Female%20Reproductive%20System/Extra%20Slides/269-2_HISTO_40X.svs/view.apml?X=0.168370491899853&Y=0.0912543984633872&zoom=17.5)
Describe the histological appearance of the corpus luteum.
Appears pale and very folded. Inner granulosa lutein cells (formed from the remaining granulosa cells) and outer theca lutein cells (come from the remaining theca interna cells). Both cell types are filled with lipid droplets and have centrally located nuclei. The theca lutein cells are, however, considerably smaller, more darkly staining and have fewer lipid filled vacuoles than the granulosa lutein cells. They are found most prominently in the infoldings right up against the granulosa lutein layer. Granulosa lutein cells contain a pigment, lipochrome, which produces the yellowish color of the corpus luteum in an unfixed ovary.
Describe the histological appearance of the endometrium in the proliferative phase.
Glands have proliferated and cover the surface. Spiral arteries are elongated and convoluted, and extend from the basal layer into the functional layer.
