Week 3 Flashcards

Question

4 layers of placental barrier/membrane

Answer 1

- foetal capillary endothelium - connective tissue of the villi - cytotrophoblast - syncytiotrophoblast

Answer 2

Metabolism - Synthesises glycogen, cholesterol, fatty acids, and nutrients and produces energy for the embryo Transfer - Oxygen, carbon dioxide, urea, uric acid and bilirubin are transferred by diffusion, as are electrolytes, free fatty acids and carbohydrates - Amino acids are transferred by a carrier mechanism, against a conc gradient, as is glucose - Vits B, C and D cross placenta readily

Answer 3

an agent that can disturb the development of an embryo or foetus

Answer 4

1. Susceptibility to teratogenesis depends on the genotype of the conceptus and the manner in which this interacts with adverse environmental factors 2. Susceptibility to teratogenesis varies with the developmental stage at the time of exposure to an adverse influence 3. Teratogenic agents act in specific ways (mechanisms) on developing cells and tissues to initiated sequences of abnormal developmental events (pathogenesis) 4. The access of adverse influences to developing tissues depends on the nature of the influence (agent) 5. The four manifestations of abnormal development are death, malformation, growth retardation and functional deficit 6. Manifestations of abnormal development increase in frequency and degree as dosage increases, from no effect to totally lethal effect

Answer 5

study of development of congenital issues caused by a teratogen

Answer 6

- environmental teratogens - drugs and chemicals industrial pollutants hormones infectious agents

Answer 7

caused blood vessels in limbs to leak, causing damage in the AER of the early limb bud and FGF signalling is affected - proximal structures don't develop

Answer 8

high doses in pregnancy can cause inner ear defects

Answer 9

if babies carry a specific genetic variant, gentamycin carries the risk of hearing loss risk during birth - if mother is septic for example

Answer 10

criss the placenta, deposited in bones and teeth at sites of calcification - teeth can become discoloured up until around 16 years of age - enamel formation affected

Answer 11

masculinization of female genitalia

Answer 12

synthetic oestrogens in utero - increased incidence of carcinoma of vagina and cervix - male offspring increased incidence of testis malformations and abnormal sperm

Answer 13

facial differences low birth weight small head circumference developmental delay memory issues poor behaviour

Answer 14

alcohol crosses placenta foetal liver not fully developed - cannot metabolise alcohol foetus has high blood alcohol concentration - lacks oxygen and nutrients - white matter development affected

Answer 15

rapidly kills proliferating cells - any cell type can be affected depending on time and dose

Answer 16

Pre-germ layer stage (weeks 1-2) - high risk of death embryonic period (weeks 3-8) - high risk of malformation of embryo foetal period (weeks 9-38) - high risk of functional disturbance of foetus

Answer 17

either have no effect of the conceptus will be spontaneously aborted - if one or two cells are killed then the embryo can compensate (regulative development) - if more cells are killed, the embryo is lost, often before pregnancy is known

Answer 18

organ systems are becoming established most teratogens are highly effective at this stage

Answer 19

functional deficits and minor issues are produced by teratogens acting at this stage susceptibility is reduced

Answer 20

extreme heat - each additional 1 degree over 24 degrees (minimum daily temp) increases infant mortality by 22.4% ambient air pollution - increases likelihood of high blood pressure during pregnancy, low birth weight, preterm birth and negative impacts on brain and lung development.

Answer 21

cremaster muscle

Answer 22

skin external spermatic fascia cremaster muscle internal spermatic fascia tunica vaginalis - parietal tunica vaginalis - visceral

Answer 23

34-35 weeks gestation

Answer 24

INSL-3 and AMH

Answer 25

testosterone

Answer 26

orchidectomy - testes removal orchidopexy - bring the testes down into the scrotum

Answer 27

leydig cells

Answer 28

sertoli cells

Answer 29

'impalpable' or 'undescended' testes

Answer 30

testes which are sometimes in the scrotum and sometimes not

Answer 31

low birthweight (<2.5kg) prematurity maternal diabetes environmental factors

Answer 32

haemotoma, pain, wound infection. testicular atrophy, recurrent cryptorchidism

Answer 33

ectopically positioned urethra, lies proximal to normal site and on the ventral aspect of the penis 1 in 300 births

Answer 34

surgery surgeon often uses foreskin to graft a new urethra and so advised against circumcision

Answer 35

any congenital condition in which development of chromosomal, gonadal or anatomic sex is atypical. 9 different types

Answer 36

a child is deficient in 21-alpha-hydroxylase enzyme - cannot synthesise aldosterone or cortisol and so has very very high sex hormone levels lots of testosterone and so a baby girl will look quite masculine could die as lack of cortisol so give them corticosteroids and salt replacement

Answer 37

intermediate mesoderm

Answer 38

pronephros - cervical region mesonephros - abdominal region metanephros - pelvic region

Answer 39

rudimentary and non-functional little blocks of mesoderm that condense to form 7-10 solid cell groups in cervical region regresses by week 4

Answer 40

derived from ointermediate mesoderm from the upper throacic and upper lumbar segments week 4 after regression of pronephros, the first excretory tubules of mesonephros appear contributes supporting cells t the genital ridge

Answer 41

the definitive kidney appears by week 5, functional by week 11 excretory units develop from the metanephric mesoderm 2 parts - ureteric bud - metanephric cap

Answer 42

posterior orifice that serves as the only opening for waste for the intestinal, reproductive and urinary tracts at early stages

Answer 43

protrusion of mesonephric duct allows urine drainage from developing kidney

Answer 44

divides cloaca by fusion with cloaca membrane to form - anterior urogenital sinus (bladder) - posterior rectal canal weeks 4-7

Answer 45

endoderm from cranial part of the urogenital sinus - apart from trigone which is formed from mesonephric ducts

Answer 46

the indifferent stage 2 pairs of genital ducts develop in weeks 5-6 - the paramesonephric ducts - uterine tube, uterus and vagina - form laterally to the mesonephric ducts - ductus deferens, epididymis

Answer 47

drain urine form the mesonephric kidney under the influence of testosterone, duct forms the ductus deferens and ejaculatory duct when mesonephros vanishes

Answer 48

develop lateral to the gonads and mesonephric ducts form funnel shaped cranial ends which open into the peritoneal cavity migrate caudally, parallel to M ducts until they reach pelvic region approach each other in midline and fuse to form the uterus

Answer 49

degenerate due to the action of anti-mullerian hormone. This is a protein made by sertoli cells of the testis

Answer 50

initially appear as a pair of longitudinal ridges - week 5, indifferent - urogenital or gonadal ridges mesoderm structure projecting into the coelomic cavity

Answer 51

originate in yolk sac move to genital ridge via dorsal mesentery - forms the primitive gonad in a cord-like structure

Answer 52

in the testis cord become horseshoe shaped cords break up into tubules LEYDIG cells begin to producte Testosterone SERTOLI cells produce anti-mullerian hormone dense connective tissue formes - tnica albuginea - seperates cords from surface epithelium

Answer 53

solid till puberty - acquire a lumen forming the Seminiferous tubules - join with rete testes - join with efferent ductules - rete testis and mesonephric duct link to form the ductus deferens

Answer 54

ovary determining gene

Answer 55

Week 6 - somatic cells grow from the coelomic epithelium Surface epithelium continues to proliferate PGCs divide by mitosis to form a pool of oogonia - meiotic arrest at 4 months, now oocytes - oocytes become associated with follicular cells

Answer 56

mesenchymal cells migrate to cloacal membrane and form a pair of cloacal folds these fuse to form genital tubercle subdivisional folds genital swellings

Answer 57

urethral folds in front anal folds posteriorly

Answer 58

driven by androgens rapid elongation of genital tubercle which becomes the phallus urethral folds get pulled together and close, forming urethra in 4th month genital swellings move caudally - scrotum

Answer 59

driven by oestrigens and absence of testosterone genital tubercle elongates only slightly to form the clitoris urethral folds and genital swellings dont fuse - U - labia minora - G - labia majora urogenital groove stays open - vestibule (where vagina and urethra open into)

Answer 60

absence or abnormal narrowing of an opening or passage

Answer 61

failure of all or part of an organ to develop

Answer 62

abnormal development

Answer 63

transient excretion at 4-5 weeks urine production from 10 weeks nephrogenesis continues to 36 weeks - all the nephrons you will ever had

Answer 64

VACTERL association is a non-random group of birth defects that frequently occur together - Vertebral and ribs - Anorectal malformation - CArdiac - Tracheoesophageal fistula - Esophageal atresia - Renal abnormalities - :imb anomalies

Answer 65

joins the yolk sac to the midgut lumen of the developing foetus and should dissapear about week 5-6 rule of twos - 2% of population - 2% are symptomatic - mostly in children under 2 - males x2 more often than females - located <2 feet proximal to ileocecal valve - 2 types of mucosal lining

Answer 66

any deviation from the expected or average form and/or function which is interpreted as abnormal

Answer 67

pattern of multiple anomalies derived from a single known or presumed prior anomaly or mechanical factor

Answer 68

a morphological defect of an organ, or region of the body, resulting from an intrinsically abnormal developmental process

Answer 69

abnormal form, shape or position of a part of the body caused by mechanical forces

Answer 70

morphologic defect of an organ, part of an organ or larger region of the body resulting from the extrinsic breakdown of, or an interference with, an originally normal developmental process.

Answer 71

an abnormal organisation of cells into tissues and its morphologic results

Answer 72

multiple anomalies thought to be pathogenetically related

Answer 73

non-random occurrence in two or more individuals of multiple congenital anomalies not known to be a sequence or syndrome

Answer 74

a tumour-like malformation composed of mature normal cells in unusual location but as a disorganised mass

Answer 75

circumscribed pouch/sac caused by herniation of lining mucosa of an organ through defect in muscular coat

Answer 76

invagination of a portion of intestine