Template:Second Trimester Timeline: Difference between revisions
mNo edit summary |
mNo edit summary |
||
Line 108: | Line 108: | ||
{{integumentary}} 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. | {{integumentary}} 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. | ||
{{touch}} Pacinian | {{touch}} {{Pacinian corpuscle}} begin to develop<ref name=Hewer1935>{{Ref-Hewer1935}}</ref> | ||
|- | |- | ||
| <center>21</center> | | <center>21</center> | ||
Line 149: | Line 149: | ||
| <center>26</center> | | <center>26</center> | ||
| | | | ||
| {{touch}} Pacinian | | {{touch}} {{Pacinian corpuscle}} well developed<ref name=Hewer1935>{{Ref-Hewer1935}}</ref> | ||
|- | |- | ||
| | | |
Latest revision as of 09:58, 27 June 2018
Links: human timeline | first trimester timeline | second trimester timeline | third trimester timeline | ||
Event | ||
Clinical second trimester | ![]() Hearing Week 12-16 - Capsule adjacent to membranous labrynth undegoes vacuolization to form a cavity (perilymphatic space) around membranous labrynth and fills with perilymph
Respiratory 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) Genital 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
hearing outer ear Week 13 - Meatal plug disc-like, innermost surface in contact with the primordial malleus, contributes to the formation of the tympanic membrane. | ||
tongue Week 14 to 15 - taste pores develop, mucous
ovary 100 days - primary follicles present nail toenails appear Head Development facial skeleton remodelling begins Hearing - Inner Ear Development Week 14 GA 16 - neural-crest-derived melanocytes, now intermediate cells of the stria vascularis, tightly integrate with Na+ /K+ -ATPase-positive marginal cells, which started to express KCNQ1 in their apical membrane.[1] | ||
Pancreas glucagon detectable in fetal plasma.
spleen Week 15 -alpha-smooth muscle actin (alpha-SMA)-positive reticulum cells scattered around the arterioles.[2] | ||
14 cm | ![]() pituitary adenohypophysis fully differentiated respiratory Week 16 to 25 lung histology - canalicular Hearing - Outer Ear Development Week 16.5 - External auditory meatus is fully patent throughout its length, lumen is still narrow and curved. Hearing - Inner Ear Development Week 16 GA 18 - cells in the outer sulcus express KCNJ10 and gap junction proteins GJB2/CX26 and GJB6/CX30, but these are not expressed in the spiral ligament.[1] gap junction cartoon neural - Cerebrum development of the periinsular sulci (week 16-17, GA 18-19 weeks)[3]
primary follicles begin to form in the ovary and are characterized by an oocyte glandular urethra forms and skin folds present | |
![]() Cerebellum Magnetic Resonance Imaging (MRI) can study the developing cerebellum from 17 to 18 weeks (GA 19 to 20 weeks). tooth Week 17 - First papilla of the permanent dentition appear (first molar) immediately behind the second milk molar, milk teeth are well advanced (Fetus 180 mm). | ||
![]() integumentary vernix caseosa covers skin spleen Week 18 - alpha-SMA-positive reticulum cells increase in number and began to form a reticular framework. An accumulation of T and B lymphocytes occurred within the framework, and a primitive white pulp was observed around the arterioles.[2] Hearing - Outer Ear Development week 18 - External auditory meatus is already fully expanded to its complete form. neural - Cerebrum central sulci and opercularization of the insula (week 18-20, GA 20-22 weeks)[3] | ||
neural week 19 neuronal migration ends and the radial glial cells that aided the migration now become transformed into astrocytes and astrocytic precursors.[4] | ||
pituitary week 20 to 24 growth hormone levels peak, then decline
integumentary lanugo, skin hair integumentary 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. touch pacinian corpuscle begin to develop[5] | ||
![]() spleen - Week 22 - antigenic diversity of the reticular framework was observed, and T and B lymphocytes were segregated in the framework. T lymphocytes were sorted into the alpha-smooth muscle actin-positive reticular framework, and the periarteriolar lymphoid sheath (PALS) was formed around the arteriole. B lymphocytes aggregated in eccentric portions to the PALS and formed the lymph follicle (LF). The reticular framework of the LF was alpha-SMA-negative. [2] neural - Cerebrum covering of the posterior insula (week 22-24, GA 24-26 weeks)[3] | ||
respiratory Week 24 to 40 lung histology - terminal sac
spleen Week 24 - marginal zone appeared in the alpha-smooth muscle actin-positive reticular framework around the white pulp.[2] tooth Week 24 - Permanent incisors and canines appear. Earliest potential survival expected if born ovary follicles can consist of growing oocytes surrounded by several layers of granulosa cells | ||
respiratory end month 6 alveolar cells type 2 appear and begin to secrete surfactant
neural - Cerebrum closure of the laeteral sulcus (Sylvian fissure or lateral fissure) (week 25-26, GA 27-28 weeks)[3] | ||
touch pacinian corpuscle well developed[5] | ||
- ↑ 1.0 1.1 Locher H, de Groot JC, van Iperen L, Huisman MA, Frijns JH & Chuva de Sousa Lopes SM. (2015). Development of the stria vascularis and potassium regulation in the human fetal cochlea: Insights into hereditary sensorineural hearing loss. Dev Neurobiol , 75, 1219-40. PMID: 25663387 DOI.
- ↑ 2.0 2.1 2.2 2.3 Satoh T, Sakurai E, Tada H & Masuda T. (2009). Ontogeny of reticular framework of white pulp and marginal zone in human spleen: immunohistochemical studies of fetal spleens from the 17th to 40th week of gestation. Cell Tissue Res. , 336, 287-97. PMID: 19255788 DOI.
- ↑ 3.0 3.1 3.2 3.3 Afif A, Bouvier R, Buenerd A, Trouillas J & Mertens P. (2007). Development of the human fetal insular cortex: study of the gyration from 13 to 28 gestational weeks. Brain Struct Funct , 212, 335-46. PMID: 17962979 DOI.
- ↑ Kadhim HJ, Gadisseux JF & Evrard P. (1988). Topographical and cytological evolution of the glial phase during prenatal development of the human brain: histochemical and electron microscopic study. J. Neuropathol. Exp. Neurol. , 47, 166-88. PMID: 3339373
- ↑ 5.0 5.1 Hewer EE. The development of nerve endings in the human foetus. (1935) J Anat. 69(3):369-79. PMID 17104543
- ↑ Garel C, Chantrel E, Brisse H, Elmaleh M, Luton D, Oury JF, Sebag G & Hassan M. (2001). Fetal cerebral cortex: normal gestational landmarks identified using prenatal MR imaging. AJNR Am J Neuroradiol , 22, 184-9. PMID: 11158907