Second Trimester: Difference between revisions
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* <ref name =" | * '''Review - Second trimester sonographic features of fetal chromosomal defects'''<ref name ="PMID24858178"><pubmed>24858178</pubmed></ref> "Advances in ultrasound technology have dramatically improved the detection of fetal chromosomal defects. Each chromosomal defect has its own syndromal pattern of detectable abnormalities prenataly. Most commonly detectable defects are Trisomies & Triploidies. Although only an invasive test can provide a definitive diagnosis, fetuses with major chromosomal abnormalities have either external or internal defects that can be recognized by detailed ultrasonographic examination at second trimester. These are defined as ultrasound markers for fetal aneuploidy. This article provides an overview and discussion on prenatal sonographic features that may suggest the presence of a common fetal chromosomal defect." [[Ultrasound]] | ||
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Revision as of 16:22, 1 March 2015
Embryology - 21 May 2024 Expand to Translate |
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Introduction
Ultrasound Image of an early Fetus (12 week)
Fetal Links: fetal | Week 10 | Week 12 | second trimester | third trimester | fetal neural | Fetal Blood Sampling | fetal growth restriction | birth | birth weight | preterm birth | Developmental Origins of Health and Disease | macrosomia | BGD Practical | Medicine Lecture | Science Lecture | Lecture Movie | Category:Human Fetus | Category:Fetal | |||
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Some Recent Findings
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More recent papers |
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This table allows an automated computer search of the external PubMed database using the listed "Search term" text link.
More? References | Discussion Page | Journal Searches | 2019 References | 2020 References Search term: Second Trimester <pubmed limit=5>Second Trimester</pubmed> |
Neural Development
Three-dimensional reconstruction of the lateral (top row) and medial (bottom row) surface of second trimester (13 to 21 week) brains to reveal the development of the Sylvian fissure or lateral sulcus (green arrow), the calcarine fissure (blue arrow), and the parieto-occipital sulcus (red arrow), respectively.
The images below are from a recent MRI study of fixed fetal brains at different weeks of development during the second trimester.[3]
- Links: Neural System - Fetal
Second Trimester Timeline
(Clinical Week 14)
Event | ||
Clinical second trimester | Week 12 - CRL 85 mm, femur length 15 mm, biparietal diameter 25 mm
Hearing Week 12-16 - Capsule adjacent to membranous labrynth undegoes vacuolization to form a cavity (perilymphatic space) around membranous labrynth and fills with perilymph Genital male and female external genital differences observable Respire Month 3-6 - lungs appear glandular, end month 6 alveolar cells type 2 appear and begin to secrete surfactant Tongue Week 12 - first differentiated epithelial cells (Type II and III) female genital canal (80 days) formed with absorption of the median septum | |
Tongue Week 12 to 13 - maximum synapses between cells and afferent nerve fibers
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Tongue Week 14 to 15 - taste pores develop, mucous | ||
Pancreas glucagon detectable in fetal plasma | ||
14 cm | Hearing Week 16-24 - Centres of ossification appear in remaining cartilage of otic capsule form petrous portion of temporal bone. Continues to ossify to form mastoid process of temporal bone.
Pituitary adenohypophysis fully differentiated Respire Week 16 to 25 lung histology - canalicular Skin 4 months - basal cell- proliferation generates folds in basement membrane; neural crest cells- (melanocytes) migrate into epithelium; embryonic connective tissue- differentiates into dermis, a loose ct layer over a dense ct layer. Beneath the dense ct layer is another loose ct layer that will form the subcutaneous layer. Ectoderm contributes to nails, hair follictles and glands. Nails form as thickening of ectoderm epidermis at the tips of fingers and toes. These form germinative cells of nail field. Cords of these cells extend into mesoderm forming epithelial columns. These form hair follocles, sebaceous and sweat glands. primary follicles begin to form in the ovary and are characterized by an oocyte glandular urethra forms and skin folds present | |
Tongue Week 18 - substance P detected in dermal papillae, not in taste bud primordia
Skin vernix caseosa covers skin Spleen SMA-positive reticulum cells increase in number and begin to form a reticular framework. PMID: 1925578 18 week post-fertilization age or 20 week gestational age (GA) developing fetal thymus histology . | ||
Pituitary week 20 to 24 growth hormone levels peak, then decline
Skin lanugo, skin hair Skin 5 months - Hair growth initiated at base of cord, lateral outgrowths form associated sebaceous glands; Other cords elongate and coil to form sweat glands; Cords in mammary region branch as they elongate to form mammary glands. Uterus Development uterine horn fimbrial development begins and continues after birth | ||
Neural brain cortical sulcation - sylvian fissure, interhemispheric fissure, callosal sulcus, parietooccipital fissure, and hippocampic fissures present(PMID:11158907
Spleen antigenic reticular framework diversity, T and B lymphocytes segregated in the framework PMID: 1925578 | ||
Respire Week 24 to 40 lung histology - terminal sac
Earliest potential survival expected if born ovarian follicles can consist of growing oocytes surrounded by several layers of granulosa cells | ||
Respire end month 6 alveolar cells type 2 appear and begin to secrete surfactant |
References
- ↑ <pubmed>24858178</pubmed>
- ↑ Report of the Workshop on Acute Perinatal Asphyxia in Term Infants, U.S. Department of Health and Human Services, Public Health Service, National Institutes of Health, National Institute of Child Health and Human Development, NIH Publication No. 96-3823, March 1996.
- ↑ <pubmed>19339620</pubmed>
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Cite this page: Hill, M.A. (2024, May 21) Embryology Second Trimester. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/Second_Trimester
- © Dr Mark Hill 2024, UNSW Embryology ISBN: 978 0 7334 2609 4 - UNSW CRICOS Provider Code No. 00098G