2010 BGD Practical 12 - Third Trimester: Difference between revisions
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* Gonad - male gonad (testes) descending (week 30) [[Development Animation - Testis Descent]] | * Gonad - male gonad (testes) descending (week 30) [[Development Animation - Testis Descent]] | ||
** 10 to 23 weeks - (9.45%) had migrated from the abdomen and were situated in the inguinal canal | ** 10 to 23 weeks - (9.45%) had migrated from the abdomen and were situated in the inguinal canal | ||
** 24 to 26 weeks - (57.9%) had migrated from the abdomen | ** 24 to 26 weeks - (57.9%) had migrated from the abdomen | ||
** 27 to 29 weeks - (16.7%) had not descended to the scrotum | ** 27 to 29 weeks - (16.7%) had not descended to the scrotum | ||
Failure of descent (cryptorchidism) either unilateral or bilateral testicular descent, occurring in up to 30% premature and 3-4% term males. | |||
References: Sampaio FJ, Favorito LA. Analysis of testicular migration during the fetal period in humans. J Urol. 1998 Feb;159(2):540-2. | Malas MA, Sulak O, Ozturk A. The growth of the testes during the fetal period. BJU Int. 1999 Oct;84(6):689-92. | References: Sampaio FJ, Favorito LA. Analysis of testicular migration during the fetal period in humans. J Urol. 1998 Feb;159(2):540-2. | Malas MA, Sulak O, Ozturk A. The growth of the testes during the fetal period. BJU Int. 1999 Oct;84(6):689-92. |
Revision as of 01:11, 31 May 2010
Practical 12: Embryo to Fetus | Second Trimester | Third Trimester | Birth | Neonatal | Abnormalities
Introduction
- Fetal Neural
- Fetal Respiratory
- Fetal Cardiovascular
- survival issues for early delivery
- fetal weight
- fetal origins hypothesis
Week 24+
- Earliest potential survival expected if born
- Respiratory Week 24 to 40 lung histology - terminal sac, end month 6 alveolar cells type 2 appear and begin to secrete surfactant
- saccule - a large thin-walled airspace lined by flattened epithelium present from about 28 weeks gestation to 2 months after birth
- Gonad - male gonad (testes) descending (week 30) Development Animation - Testis Descent
- 10 to 23 weeks - (9.45%) had migrated from the abdomen and were situated in the inguinal canal
- 24 to 26 weeks - (57.9%) had migrated from the abdomen
- 27 to 29 weeks - (16.7%) had not descended to the scrotum
Failure of descent (cryptorchidism) either unilateral or bilateral testicular descent, occurring in up to 30% premature and 3-4% term males.
References: Sampaio FJ, Favorito LA. Analysis of testicular migration during the fetal period in humans. J Urol. 1998 Feb;159(2):540-2. | Malas MA, Sulak O, Ozturk A. The growth of the testes during the fetal period. BJU Int. 1999 Oct;84(6):689-92.
Fetal Weight
Fetal Birth
Most of the serious illness and mortality is concentrated in the 1 to 2 percent of infants who are born at less than 32 weeks of gestation (week 30) and who weigh less than 1500 g.
Teratogens - Infant Drug Clearance
The drug clearance data below are only approximate calculated rates for the fetus and infant from NZ Drug Safety in Lactation
Post-conceptual Age (weeks) | Clearance of Drug (percentage of adults) |
24-28 | 5% |
28-34 | 10% |
34-40 | 33% |
40-44 | 50% |
44-68 | 66% |
> 68 | 100% |
Practical 12: Embryo to Fetus | Second Trimester | Third Trimester | Birth | Neonatal | Abnormalities
Additional Information
The following information is a detailed timeline of third trimester development and content does not form part of the current practical class.
Third Trimester
(Clinical Week 28)
Event | ||
Clinical third trimester | Sense - Hearing 3rd Trimester - vibration acoustically of maternal abdominal wall induces startle respone in fetus. | |
Respire Month 7 - respiratory bronchioles proliferate and end in alveolar ducts and sacs | ||
Genital male gonad (testes) descending | ||
Neural brain cortical sulcation - primary sulci present PMID:11158907 | ||
Neural brain cortical sulcation - insular, cingular, and occipital secondary sulci present PMID:11158907 | ||
Birth | Clinical Week 40
Heart pressure difference closes foramen ovale leaving a fossa ovalis Thyroid TSH levels increase, thyroxine (T3) and T4 levels increase to 24 h, then 5-7 days postnatal decline to normal levels Adrenal - zona glomerulosa, zona fasiculata present
|
Glossary Links
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- 2010 BGD: Lecture 1 | Lecture 2 | Practical 3 | Practical 6 | Practical 12
Cite this page: Hill, M.A. (2024, April 23) Embryology 2010 BGD Practical 12 - Third Trimester. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/2010_BGD_Practical_12_-_Third_Trimester
- © Dr Mark Hill 2024, UNSW Embryology ISBN: 978 0 7334 2609 4 - UNSW CRICOS Provider Code No. 00098G