Talk:Timeline human development
Collapsible Tables
zygote | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
|
Developmental Map
- Gametes Meiosis
- Zygote Fertilization Mitosis
- Morula Mitosis
- Blastocyst
- Trophoblast
- Embryoblast
- Epiblast Gastrulation
- Ectoderm
- Neural Plate (Central Nervous System)
- Brain
- Spinal Cord
- Neural Crest
- Sensory Ganglia (Dorsal Root Ganglia)
- Sympathetic Ganglia
- Placodes
- Surface Ectoderm (Epidermis)
- Neural Plate (Central Nervous System)
- Mesoderm
- Axial Mesoderm (Notochord)
- Paraxial Mesoderm
- Unsegmented Paraxial Mesoderm
- Segmented Paraxial Mesoderm (Somites)
- Dermamyotome
- Dermatome
- Myotome
- Epaxial
- Hypaxial
- Trunk Muscles
- Limb Muscles
- Sclerotome
- Vertebra
- Intervertebral Disc
- Dermamyotome
- Intermediate Mesoderm
- Renal
- Genital
- Lateral Plate Mesoderm
- Somatic Mesoderm
- Intraembryonic Coelom
- Splanchnic Mesoderm
- Endoderm
- Germ Cells
- Ectoderm
- Hypoblast
- Epiblast Gastrulation
Links are to the original UNSW Embryology webpages: Timeline Human Development (simple) | Timeline Human Development (detailed)
![Early zygote.jpg](/embryology/images/thumb/e/e1/Early_zygote.jpg/210px-Early_zygote.jpg)
![Newborn.jpg](/embryology/images/thumb/7/7e/Newborn.jpg/300px-Newborn.jpg)
Neural Crest
- Links: Neural Crest Development
The development of the neural crest in the human
J Anat. 2007 Sep;211(3):335-51.
O'Rahilly R, Müller F.
School of Medicine, University of California, Davis, California, USA.
Abstract
The first systematic account of the neural crest in the human has been prepared after an investigation of 185 serially sectioned staged embryos, aided by graphic reconstructions. As many as fourteen named topographical subdivisions of the crest were identified and eight of them give origin to ganglia (Table 2). Significant findings in the human include the following.
(1) An indication of mesencephalic neural crest is discernible already at stage 9, and trigeminal, facial, and postotic components can be detected at stage 10.
(2) Crest was not observed at the level of diencephalon 2. Although pre-otic crest from the neural folds is at first continuous (stage 10), crest-free zones are soon observable (stage 11) in Rh.1, 3, and 5.
(3) Emigration of cranial neural crest from the neural folds at the neurosomatic junction begins before closure of the rostral neuropore, and later crest cells do not accumulate above the neural tube.
(4) The trigeminal, facial, glossopharyngeal and vagal ganglia, which develop from crest that emigrates before the neural folds have fused, continue to receive contributions from the roof plate of the neural tube after fusion of the folds.
(5) The nasal crest and the terminalis-vomeronasal complex are the last components of the cranial crest to appear (at stage 13) and they persist longer.
(6) The optic, mesencephalic, isthmic, accessory, and hypoglossal crest do not form ganglia. Cervical ganglion 1 is separated early from the neural crest and is not a Froriep ganglion.
(7) The cranial ganglia derived from neural crest show a specific relationship to individual neuromeres, and rhombomeres are better landmarks than the otic primordium, which descends during stages 9-14.
(8) Epipharyngeal placodes of the pharyngeal arches contribute to cranial ganglia, although that of arch 1 is not typical.
(9) The neural crest from rhombomeres 6 and 7 that migrates to pharyngeal arch 3 and from there rostrad to the truncus arteriosus at stage 12 is identified here, for the first time in the human, as the cardiac crest.
(10) The hypoglossal crest provides cells that accompany those of myotomes 1-4 and form the hypoglossal cell cord at stages 13 and 14.
(11) The occipital crest, which is related to somites 1-4 in the human, differs from the spinal mainly in that it does not develop ganglia.
(12) The occipital and spinal portions of the crest migrate dorsoventrad and appear to traverse the sclerotomes before the differentiation into loose and dense zones in the latter.
(13) Embryonic examples of synophthalmia and anencephaly are cited to emphasize the role of the neural crest in the development of cranial ganglia and the skull.
PMID 17848161
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2375817
http://onlinelibrary.wiley.com/doi/10.1111/j.1469-7580.2007.00773.x/abstract
Test new format
Embryology - 16 Jun 2024 ![]() ![]() ![]() |
---|
Google Translate - select your language from the list shown below (this will open a new external page) |
العربية | català | 中文 | 中國傳統的 | français | Deutsche | עִברִית | हिंदी | bahasa Indonesia | italiano | 日本語 | 한국어 | မြန်မာ | Pilipino | Polskie | português | ਪੰਜਾਬੀ ਦੇ | Română | русский | Español | Swahili | Svensk | ไทย | Türkçe | اردو | ייִדיש | Tiếng Việt These external translations are automated and may not be accurate. (More? About Translations) |
Week -2
(GA Clinical Week 1)
Event | ||
Menstrual Phase |
Menstrual Cycle changes: Uterine endometrium (loss), Ovary (Follicle Development) | |
![]() | ||
Proliferative Phase | ![]() ![]() | |
Week -1
(Clinical Week 2)
Menstrual cycle | Event | |
Proliferative Phase | ||
![]() ![]() ![]() ![]() | ||
![]() ![]() ![]() | ||
Ovulation
Capacitation |
![]() ![]() ![]() |
Week 1
Week 1 (GA Clinical week 3) | |||||||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Week 1 of fertilisation age begins on the day of fertilisation, while the clinical gestational age (GA) is measured from the first day of the last menstrual period (LMP).
Concepts
|
![]() Week 1 summary | ||||||||||||||
| |||||||||||||||
|
Event | ||
Secretory Phase | ![]() ![]() ![]() ![]() | |
Stage 2 | ![]() ![]() | |
![]() | ||
Stage 3 | ![]() | |
![]() ![]() | ||
Stage 4 | Adplantation | |
Stage 5 | ![]() ![]() |
Week 2
Event | ||
![]() | ||
Stage 6 | ![]() ![]() | |
Week 3
Event | ||
Stage 7 | ![]() ![]() ![]() | |
Stage 8 | ![]() ![]() | |
Stage 9 | ![]() ![]() Neural the three main divisions of the brain, which are not cerebral vesicles, can be distinguished while the neural groove is still completely open Neural Crest mesencephalic neural crest is visible[1] | |
Heart cardiogenesis, week 3 begins as paired heart tubes. |
Week 4
Event | ||
Stage 10 | ![]() ![]() ![]() Neural Crest differentiation at spinal cord level from day 22 until day 26 Neural neural folds begin to fuse near the junction between brain and spinal cord, when Neural Crest cells are arising mainly from the neural ectoderm Neural Crest trigeminal, facial, and postotic ganglia components visible[1] Neural Crest migration of vagal level neural crest cells begins (7-10 somite stage) Neural rostral neural tube forms 3 primary brain vesicles (week 4) Respiratory Week 4 - laryngotracheal groove forms on floor foregut. | |
Heart begins to beat in Humans by day 22-23, first functioning embryonic organ formed. | ||
Stage 11 | ![]() Thyroid thyroid median endodermal thickening in the floor of pharynx Neural rostral (or cephalic) neuropore closes within a few hours; closure is bidirectional, it takes place from the dorsal and terminal lips and may occur in two areas simultaneously. The two lips, however, behave differently. Ventricular System Optic ventricle appears and the neural groove/tube space is initially filled with amniotic fluid.[2] | |
Stage 12 | ![]() ![]() Pituitary Week 4 hypophysial pouch, Rathke's pouch, diverticulum from roof Liver septum transversum forming liver stroma and hepatic diverticulum forming hepatic trabeculae[3] Neural caudal neuropore takes a day to close (closure is approximately at future somitic pair 31/sacral vertebra 2) Neural secondary neurulation begins Ventricular System onset of the ventricular system and separates the ependymal from the amniotic fluid.[2] Neural Crest cardiac crest, neural crest from rhombomeres 6 and 7 that migrates to pharyngeal arch 3 and from there the truncus arteriosus [1] Neural Crest vagal neural crest enter the foregut (20-25 somite stage) | |
Stage 13 | ![]() ![]() telencephalon cavity appears Neural - Vascular Development - hindbrain is supplied by two parallel neural arteries (or channels) that obtain their blood supply from carotid-vertebrobasilar anastomoses given by the pharyngeal arch arteries; trigeminal artery, the otic artery, hypoglossal artery, and the proatlantal artery.[5] Liver epithelial cord proliferation enmeshing stromal capillaries[3] Smell Crest comes from the nasal plates[6] Skin 4 weeks - simple ectoderm epithelium over mesenchyme Skin 1-3 months ectoderm- germinative (basal) cell repeated division of generates stratified epithelium; mesoderm- differentiates into connective tissue and blood vessels Vision Optic vesicle lies close to the surface ectoderm. The surface ectoderm overlying the optic vesicle, in response to this contact, has thickened to form the lens placode.[7] Diaphragm - pleuroperitoneal fold (PPF) first discernible in human embryos (CRL 6mm).[8] |
Week 5
Event | ||
Pituitary Week 5 elongation, contacts infundibulum, diverticulum of diencephalon
Heart Week 5 septation starts, atrial and ventricular Respiratory Week 5 left and right lung buds push into the pericardioperitoneal canals (primordia of pleural cavity) Respiratory Week 5 to 17 lung histology - pseudoglandular Hearing Week 5 cochlear part of otic vesicle elongates (humans 2.5 turns) | ||
Stage 14 | ![]() ![]() Mesoderm continued segmentation of paraxial mesoderm (somite pairs), heart prominence Head 1st, 2nd and 3rd pharyngeal arch, forebrain, site of lens placode, site of otic placode, stomodeum Body - heart, liver, umbilical cord, mesonephric ridge visible externally as bulges. Limb upper and lower limb buds growing. Abdominal Wall mesoderm of the primary body wall coalesced in the ventral midline to create the abdominal cavity.[9] Neural first appearance of the future cerebral hemispheres. Cerebellar plate differentiated to an intermediate layer, and future rhombic lip identifiable[10] Neural - Vascular Development - basilar artery forms from the consolidation of the neural arteries.[5] Ventricular System Subarachnoid space initially as irregular spaces on the ventral surface of the spinal cord. 16228957 Liver hepatic gland and its vascular channels enlarge, hematopoietic function appears[3] Eye - Lens the lens placode is indented by the lens pit.[7] | |
Stage 15 | ![]() Neural cranial nerves (except olfactory and optic) are identifiable in more advanced embryos[11] Neural - Vascular Development - vertebral arteries form from transverse anastomoses between cervical intersegmental arteries, beginning with the proatlantal artery and proceeding downward to the 6th intersegmental artery,[5] Eye - Lens the lens pit is closed. The lens vesicle and optic cup lie close to the surface ectoderm and appear to press against the surface.[7] | |
Vision 35 to 37 days retinal pigment present |
Week 6
Event | ||
Pituitary Week 6 - connecting stalk between pouch and oral cavity degenerates
Parathyroid Week 6 - diverticulum elongate, hollow then solid, dorsal cell proliferation Thymus Week 6 - diverticulum elongate, hollow then solid, ventral cell proliferation Adrenal Week 6 - fetal cortex forms from mesothelium adjacent to dorsal mesentery, medulla neural crest cells from adjacent sympathetic ganglia Respire Week 6 - descent of heart and lungs into thorax. Pleuroperitoneal foramen closes Tongue Week 6 - descent of heart and lungs into thorax. Pleuroperitoneal foramen closes gustatory papilla, caudal midline near the foramen caecum (week 6 to 7 - nerve fibers approach the lingual epithelium) | ||
Stage 16 | ![]() Neural - Vascular Development - development of the middle cerebral artery is first identified as small buds originating proximal to the anterior cerebral artery on the anterior division of the primitive internal carotid artery.[5] Limb upper limb bud nerves median nerve, radial nerve and ulnar nerve entered into hand plate, myoblasts spindle shaped and oriented parallel to limb bud axis. Abdominal Wall muscle cell migration about 25% of the hemicircumference of the abdominal cavity, the lateral plate mesoderm has become more condensed and thicker in the area around the myoblasts.[9] Heart outflow tract elliptical configuration with four cushions, the two larger fusing at this stage. Semilunar valve leaflets form at the downstream end of the cushions Head lip and palate components of the upper lip, medial nasal prominence and maxillary process present, median palatine process appears. Eyelid prior to the development of the eyelids, one small sulcus or groove forms above the eye (eyelid groove) and another below it.[7] | |
Stage 17 | ![]()
| |
Heart separation of common cardiac outflow (aortic arch and pulmonary aorta) |
Week 7
Event | ||
Pancreas Week 7 to 20 pancreatic hormones secretion increases, small amount maternal insulin
Respiratory Week 7 - enlargement of liver stops descent of heart and lungs | ||
Stage 18 | ![]() Limb Bone forms by endochondrial ossification and throughout embryo replacement of cartilage with bone (week 5-12). Neural Smell vomeronasal fibres and nervus terminalis[6] Liver obturation due to epithelial proliferation, bile ducts became reorganized, continuity between liver cells and gut[3] Ventricular System duramater appears and spaces surround the circumference of the spinal cord, which coalesce and contain many blood vessels.[14] Genital - Female Development opening of the paramesonephric (Müllerian) duct to the coelomic cavity formed as an invagination of the coelomic epithelium[15] Abdominal Wall separation of the myoblasts into distinct inner and outer layers, with unidirectional orientation. Abdominal wall thicker in the region where secondary structures were forming compared with the primary body wall region, dorsally outermost layer of connective tissue approximately half of this thickness.[9] | |
Liver (stage 18 to 23) biliary ductules developed in periportal connective tissue produces ductal plates that receive biliary capillaries[3] | ||
Stage 19 | ![]()
| |
Week 8
Event | ||
Stage 20 | ![]() Head scalp vascular plexus visible Limb upper limbs begin to rotate ventrally Neural amygdaloid body has at least four individual nuclei[23] oculomotor nerve shows a dorsolateral and a ventromedial portion rhombic lip (rhombencephalon) formation of the cerebellum (intermediate layer) and of the cochlear nuclei cerebellum cell layer (future Purkinje cells) develops choroid plexuses of the fourth and lateral ventricles | |
Gastrointestinal Tract anal membrane perforates | ||
Stage 21 | ![]() Neural cortical plate appears in the area of future insula[24] Neural - Vascular Development - formation of the anterior communicating artery.[5] Limb upper and lower limbs rotate Intraembryonic Coelom pericardioperitoneal canals close Abdominal Wall Myoblasts have reached the ventral midline and myotubes were present and oriented uniformly within all muscle groups. The rectus abdominis formed distinct bundles of muscle. Connective tissue layers comprised the majority of the thickness of the abdominal wall, outermost layer of connective tissue accounted for the majority of this thickness.[9] | |
Stage 22 | ![]() Limb fingers and toes lengthen Smell Stage 22 to early fetal period - migratory streams of neurons from the subventricular zone of the olfactory bulb towards the future claustrum[6] Uterus Vagina fused duct (uterovaginal canal) bifurcated at the caudal portion at Carnegie stages 22 and 23[15] | |
Genital 8 Weeks Testis - mesenchyme, interstitial cells (of Leydig) secrete testosterone, androstenedione
Genital 8 to 12 Weeks - hCG stimulates testosterone production Tongue Week 8 - nerves penetrate epitheilai basal lamina and synapse with undifferentiated, elongated, epithelial cells (taste bud progenitor cell)[25] | ||
Stage 23 | ![]() Mesoderm heart prominence, ossification continues Head nose, eye, external acoustic meatus, eyelids, external ears, rounded head Body - straightening of trunk, umbilical cord, intestines herniated at umbilicus Limb upper limbs longer and bent at elbow, hands and feet turned inward, foot with separated digits, wrist, hand with separated digits Extraembryonic Coelom chorionic cavity is now lost by fusion with the expanding amniotic cavity Neural rhombencephalon, pyramidal decussation present, nuclei and tracts similar to those present in the newborn cerebellum present as only a plate connected to midbrain and hindbrain through fibre bundles[26] Axial Skeleton vertebral column 33 or 34 cartilaginous vertebrae (20-33 mm in total length), vertebral pedicles, articular and transverse processes identifiable (no spinous processes)[27] Abdominal Wall Rectus muscle forms 2 or 3 distinct layers with myotube orientation uniform in all muscles. The external oblique and internal oblique started to expand in thickness, transversus a thin layer of muscle.[9] | |
Week 8 | Stomach Week 8 - Gastrin containing cells in stomach antrum. Somatostatin cells in both the antrum and the fundus.
Genital - Female Development paired paramesonephric (Müllerian) ducts contact each other and are fused into a single tube that separates again and returns to the mesonephric (Wolffian) ducts. The paramesonephric ducts have not yet reached the urogenital sinus.[15] |
Week 9
(GA Clinical Week 11)
Event | ||
Fetal Period | ![]() Hearing Week 9 - mesenchyme surrounding membranous labrynth (otic capsule) chondrifies Smell Embryonic/Fetal transition - localized incomplete lamination of the olfactory bulb[6] | |
Week 9 - CRL 43 mm, femur length 6 mm
9 weeks CRL 50 mm - Genital genitalia in both sexes look identical[28] uterus - paramesonephric ducts come into apposition with the urorectal septum and begin to fuse |
Week 10
(GA Clinical Week 12)
Event | ||
![]() Gastrointestinal Tract Week 10 intestines in abdomen Pituitary growth hormone and ACTH detectable Pancreas Week 10 glucagon (alpha) differentiate first, somatostatin (delta), insulin (beta) cells differentiate, insulin secretion begins Tongue Week 10 shallow grooves above the taste bud primordium Stomach Week 10 - Glucagon containing cells in stomach fundus. Nail Development fingernails appear Hearing - Outer Ear Development Week 10 - Meatal plug extends in a disc-like fashion, the meatus is boot-shaped with a narrow neck and the sole of the meatal plug spreading widely to form the future tympanic membrane medially. Proximal portion of the neck starts to be resorbed. Hearing - Inner Ear Development Week 10 - neural-crest-derived melanocytes migrate into the cochlea. They penetrate the basement membrane of the lateral wall epithelium and develop into the intermediate cells of the stria vascularis.[29] | ||
Week 10 - CRL 55 mm, femur length 9 mm, biparietal diameter 17 mm |
Week 11
(GA Clinical Week 13)
Event
Neural - Cerebrum appearance of the first sulcus (week 11-15, GA 13-17 weeks)[30] | ||
![]() Thyroid colloid appearance in thyroid follicles, iodine and thyroid hormone (TH) synthesis Stomach Week 11 - Serotonin containing cells in both the antrum and the fundus. | ||
Week 11 - CRL 68 mm, femur length 12 mm, biparietal diameter 20 mm |
Second Trimester
(GA Clinical Week 14) Second Trimester
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 Development 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 Development 100 days - primary follicles present Nail Development 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.[29] | ||
Pancreas glucagon detectable in fetal plasma.
Spleen Week 15 -alpha-smooth muscle actin (alpha-SMA)-positive reticulum cells scattered around the arterioles. [31] Fetal Timeline | ||
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.[29] gap junction cartoon Neural - Cerebrum development of the periinsular sulci (week 16-17, GA 18-19 weeks)[30]
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 Development 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). | ||
![]() Skin 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. [31] 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)[30] | ||
Neural week 19 neuronal migration ends and the radial glial cells that aided the migration now become transformed into astrocytes and astrocytic precursors.[32] | ||
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. | ||
![]() 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. [31] Neural - Cerebrum covering of the posterior insula (week 22-24, GA 24-26 weeks)[30] | ||
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.[31] Tooth Development Week 24 - Permanent incisors and canines appear. Earliest potential survival expected if born ovarian 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)[30] |
Third Trimester
(GA Clinical Week 28) Third Trimester
Event | ||
Clinical third trimester | ![]() | |
Respire Month 7 - respiratory bronchioles proliferate and end in alveolar ducts and sacs | ||
Tooth Development Week 29 - Permanent premolars (correspond to the milk molars) appear. | ||
Genital male gonad (testes) descending | ||
Nail Development fingernails reach digit tip | ||
Neural brain cortical sulcation - primary sulci present[33] | ||
Neural brain cortical sulcation - insular, cingular, and occipital secondary sulci present[33] | ||
![]() Lens Development - lens growth and interocular distance plateaus after 36 weeks of gestation[34] | ||
Birth | ![]() 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
|
Postnatal
Event | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Vision Development - eye globe growth plateaus after 42 weeks of gestation[34] | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Testis | Spermatozoa - about 2 months of age, primordial germ cells (gonocytes) are replaced by adult dark (Ad) and pale (Ap) spermatogonia forming the spermatogonial stem cell (SSC) population that at puberty will commence differentiation into spermatozoa. | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Neural Hearing (6 months to 5 years) thalamocortical afferents to the deeper cortical layers mature and are the first source of input to the auditory cortex[35]
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Adrenal - Year 3 zona reticularis present.
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Neural Hearing - (5 to 12 years) commissural and association axons in the superficial cortical layers allows communication between subdivisions of the auditory cortex[35] | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Puberty - Female | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Puberty - Male |
References
- ↑ 1.0 1.1 1.2 <pubmed>17848161</pubmed>
- ↑ 2.0 2.1 <pubmed>2285038</pubmed>
- ↑ 3.0 3.1 3.2 3.3 3.4 <pubmed>9407542</pubmed>
- ↑ <pubmed>3354839</pubmed>
- ↑ 5.0 5.1 5.2 5.3 5.4 5.5 <pubmed>26060802</pubmed>| J Stroke.
- ↑ 6.0 6.1 6.2 6.3 6.4 <pubmed>15604533</pubmed>
- ↑ 7.0 7.1 7.2 7.3 7.4 7.5 <pubmed>7364662</pubmed>
- ↑ 8.0 8.1 <pubmed>19711422</pubmed>
- ↑ 9.0 9.1 9.2 9.3 9.4 9.5 9.6 <pubmed>22976993</pubmed>| PMC3976953 | Anat Rec (Hoboken)
- ↑ <pubmed>3377191</pubmed>
- ↑ <pubmed>3213956</pubmed>
- ↑ <pubmed>2751117</pubmed>
- ↑ <pubmed>2802187</pubmed>
- ↑ 14.0 14.1 <pubmed>15478101</pubmed>
- ↑ 15.0 15.1 15.2 15.3 <pubmed>12740945</pubmed>
- ↑ <pubmed>7364662</pubmed>
- ↑ Keibel F. and Mall FP. Manual of Human Embryology II. (1912) J. B. Lippincott Company, Philadelphia.
- ↑ Congdon ED. Transformation of the aortic-arch system during the development of the human embryo. (1922) Contrib. Embryol., Carnegie Inst. Wash. Publ 277, 14:47-110.
- ↑ Wells LJ. Development of the human diaphragm and pleural sacs. (1954) Contrib. Embryol., Carnegie Inst. Wash. Publ. 603, 35: 107-134.
- ↑ Jirásek JE. Development of the Genital System and Male Pseudohermaphroditism. (1971) Johns Hopkins Press, Baltimore.
- ↑ Wilson KM. Origin and development of the rete ovarii and the rete testis in the human embryo. (1926) Carnegie Instn. Wash. Publ. 362, Contrib. Embryol., Carnegie Inst. Wash., 17:69-88.
- ↑ Gasser RL. Atlas of Human Embryos. (1975) Harper & Row, Hagerstown, Maryland.
- ↑ 23.0 23.1 <pubmed>2268071</pubmed>
- ↑ 24.0 24.1 <pubmed>2252222</pubmed>
- ↑ <pubmed>8955790</pubmed>
- ↑ <pubmed>2244584</pubmed>
- ↑ <pubmed>7216919</pubmed>
- ↑ <pubmed>17875485</pubmed>
- ↑ 29.0 29.1 29.2 <pubmed>25663387</pubmed>
- ↑ 30.0 30.1 30.2 30.3 30.4 <pubmed>17962979</pubmed>
- ↑ 31.0 31.1 31.2 31.3 <pubmed>19255788</pubmed>
- ↑ <pubmed>3339373</pubmed>
- ↑ 33.0 33.1 33.2 <pubmed>11158907</pubmed>
- ↑ 34.0 34.1 <pubmed>19541779</pubmed>
- ↑ 35.0 35.1 <pubmed>12018354</pubmed>