Category:Fetal

From Embryology

This Embryology category shows pages and media related to fetal development.

In human development the fetal period occurs after the end of the embryonic period at post-fertilisation week 8 or GA week 10. Late first and the entire second and third trimester are the fetal development period.


Fetal Links: fetal | Week 10 | Week 12 | second trimester | third trimester | fetal neural | Fetal Blood Sampling | birth weight | Developmental Origins of Health and Disease | fetal growth restriction | macrosomia | BGD Practical | Medicine Lecture | Science Lecture | Lecture Movie | preterm birth | birth | Category:Human Fetus | Category:Fetal
Historic Embryology  
1940 Fetus Physiology
Carnegie Fetal: 95 | 96 | 142 | 145 | 184 | 211 | 217 | 300 | 362 | 448 | 449 | 538 | 590 | 607 | 625 | 662 | 693 | 847 | 858 | 922 | 928 | 948 | 972 | 1318 | 1388 | 1455 | 1591 | 1597b | 1656 | 1686 | 2250a | 2250b | 3990 | 5652 | 6581 | 7218


Second Trimester Timeline 
Links: human timeline | first trimester timeline | second trimester timeline | third trimester timeline
Week
Stage
Event
12
Clinical second trimester Fetal head lateral.jpg 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

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

13
  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.  

14
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]

15
  Pancreas glucagon detectable in fetal plasma.

spleen Week 15 -alpha-smooth muscle actin (alpha-SMA)-positive reticulum cells scattered around the arterioles.[2]

16
14 cm Fetal size change.jpg 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

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]


integumentary 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

17
Brain week 17 histology.jpg Neural - Brain development histology week 17

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).

18
Bailey095.jpgtongue Week 18 - substance P detected in dermal papillae, not in taste bud primordia

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]

19
  neural week 19 neuronal migration ends and the radial glial cells that aided the migration now become transformed into astrocytes and astrocytic precursors.[4]
20
  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]

21
   
22
  Gray0038.jpg Neural brain cortical sulcation - sylvian fissure, interhemispheric fissure, callosal sulcus, parietooccipital fissure, and hippocampic fissures present[6]

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]

23
   
24
  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

25
  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]

26
  touch pacinian corpuscle well developed[5]
Systems  
Systems: bone timeline | eye neural crest timeline | heart abnormality timeline | hearing EAM timeline | muscle timeline | ovary timeline | placental villi timeline | shoulder timeline | smell timeline | spleen timeline | ventricular timeline


Third Trimester Timeline
Links: human timeline | first trimester timeline | second trimester timeline | third trimester timeline
Week
Stage
Event
Clinical third trimester Fetal size change.jpg hearing 3rd Trimester - vibration acoustically of maternal abdominal wall induces startle respone in fetus.
27
 
28
  respiratory Month 7 - respiratory bronchioles proliferate and end in alveolar ducts and sacs
29
 

tooth Week 29 - Permanent premolars (correspond to the milk molars) appear.

30
   

Genital male gonad (testes) descending

31
 
32
  nail fingernails reach digit tip
33
  neural brain cortical sulcation - primary sulci present[6]
34
  neural brain cortical sulcation - insular, cingular, and occipital secondary sulci present[6]
35
   
36
  Frazer006 bw600.jpg Nail Development toenails reach digit tip

Lens Development - lens growth and interocular distance plateaus after 36 weeks of gestation[7]

37
   
38
Birth Newborn.jpg 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

Systems  
Systems: bone timeline | eye neural crest timeline | heart abnormality timeline | hearing EAM timeline | muscle timeline | ovary timeline | placental villi timeline | shoulder timeline | smell timeline | spleen timeline | ventricular timeline


Carnegie Collection - Fetal  
Serial No. Size CRL (mm) Grade Fixative Embedding Medium Plane Thinness (µm) Stain Point Score Sex Year Notes
95 40 catalogued as CRL 40 but development suggests 50 stage. Spinal cord - Kunitomo (1920)[8] Colon - Lineback (1920)[9]
96 50 Brain venous sinuses - Streeter (1915)[10] Spinal cord - Kunitomo (1920)[8] Brain vascular - Streeter (1921)[11] Brain weight - Jenkins (1921)[12]
142 125 Spinal cord - Kunitomo (1920)[8]
145 33 Spinal cord - Kunitomo (1920)[8]
184 50 34 vertebrae, 31 spinal ganglia, Spinal cord - Kunitomo (1920)[8]
211 33 34 vertebra, 31 spinal ganglia, Spinal cord - Kunitomo (1920)[8]
217 45 Male Genital - Spaulding (1921)[13]
300 73 85 days, Bone ossification - Mall (1906)[14]
362 30 Spinal cord - Kunitomo (1920)[8]
448 52 Colon - Lineback (1920)[9]
449 36 Spinal cord - Kunitomo (1920)[8]
538
590 21 to 23 Male Genital - Spaulding (1921)[13]
607 37 Male Genital - Spaulding (1921)[13]
625 220 Temporomandibular joint - Moffatt (1957)[15]
662 80 Spinal cord - Kunitomo (1920)[8]
693 45 Male Genital - Spaulding (1921)[13]
847 58.8 Male Genital - Spaulding (1921)[13]
858 57.25 Temporomandibular joint - Moffatt (1957)[15]
922 37
928 120 Spinal cord - Kunitomo (1920)[8]
948 45 Male Genital - Spaulding (1921)[13]
972 37 34 vertebrae, 30 spinal ganglia, Spinal cord - Kunitomo (1920)[8]
1318 37 Temporomandibular joint - Moffatt (1957)[15]
1388 51 Female Genital - Spaulding (1921)[13]
1455 78.5 Temporomandibular joint - Moffatt (1957)[15]
1591 36 subcutaneous vascular plexus - Finley (1923)[16]
1656 67 34 vertebrae, Spinal cord - Kunitomo (1920)[8]
1686 40 Male Genital - Spaulding (1921)[13]
3990 49 Temporomandibular joint - Moffatt (1957)[15]
4473 43 20 Spinal cord meninges - Sensenig (1951)[17]
4475 48 20 Spinal cord meninges - Sensenig (1951)[17]
5652 49 Temporomandibular joint - Moffatt (1957)[15]
6581 75 Temporomandibular joint - Moffatt (1957)[15]
7218 80 20 um Spinal cord meninges - Sensenig (1951)[17]
1597b 47 Female Genital - Spaulding (1921)[13]
2250a 40 Female Genital - Spaulding (1921)[13]
2250b 36 Female Genital - Spaulding (1921)[13]
This table currently contains only has embryo number information.

Abbreviations

  • Size - E. is the greatest length of the embryo and Ch. is the mean diameter of the chorion.
  • Grade - total grade of the specimen and includes both its original quality and the condition of the mounted sections.
  • Embedding medium - paraffin (P) or a combination of celloidin and paraffin (C-P).
  • Fixative - formalin (Formol), alcohol and formalin (Alc, formol), Bouin (Bouin solution)
  • Stain -
  •  ? - unknown or not determined.
References
  1. 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. 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. 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.
  4. 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. 5.0 5.1 Hewer EE. The development of nerve endings in the human foetus. (1935) J Anat. 69(3):369-79. PMID 17104543
  6. 6.0 6.1 6.2 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
  7. Paquette LB, Jackson HA, Tavaré CJ, Miller DA & Panigrahy A. (2009). In utero eye development documented by fetal MR imaging. AJNR Am J Neuroradiol , 30, 1787-91. PMID: 19541779 DOI.
  8. 8.00 8.01 8.02 8.03 8.04 8.05 8.06 8.07 8.08 8.09 8.10 8.11 Kunitomo K. The development and reduction of the tail and of the caudal end of the spinal cord (1920) Contrib. Embryol., Carnegie Inst. Wash. Publ. 272, 9: 163-198.
  9. 9.0 9.1 Lineback PE. Studies on the longitudinal muscle of the human colon, with special reference to the development of the taeniae. (1920) Contrib. Embryol., Carnegie Inst. Wash. Publ. 50
  10. Streeter GL. The development of the venous sinuses of the dura mater in the human embryo. (1915) Amer. J Anat.18: 145-178.
  11. Streeter GL. The developmental alterations in the vascular system of the brain of the human embryo. (1921) Contrib. Embryol., Carnegie Inst. Wash. 8:7-38.
  12. Jenkins GB. Relative weight and volume of the component parts of the brain of the human embryo at different stages of development. (1921) Contrib. Embryol., Carnegie Inst. Wash., 59: 5-54.
  13. 13.00 13.01 13.02 13.03 13.04 13.05 13.06 13.07 13.08 13.09 13.10 Spaulding MH. The development of the external genitalia in the human embryo. (1921) Contrib. Embryol., Carnegie Inst. Wash. Publ. 81, 13: 69 – 88.
  14. Mall FP. On ossification centers in human embryos less than one hundred days old. (1906) Amer. J Anat. 5:433-458.
  15. 15.0 15.1 15.2 15.3 15.4 15.5 15.6 Moffatt BC. The prenatal development of the human temporomandibular joint. (1957) Carnegie Instn. Wash. Publ. 611, Contrib. Embryol., 36: .
  16. Finley EB. The development of the subcutaneous vascular plexus in the head of the human embryo. (1923) Contributions to Embryology Carnegie Institution No.71; 155-161.
  17. 17.0 17.1 17.2 Sensenig EC. The early development of the meninges of the spinal cord in human embryos. (1951) Contrib. Embryol., Carnegie Inst. Wash. Publ. 611,
Fertilization and Gestational Age - Crown-Rump Length (measured by ultrasound
Fertilization Age
(days)
Gestational Age
GA (week.day)
Crown-Rump
Length (mm)
37 5.2 1
38 5.3 2
39 5.4 3
40 55 3
41 5.6 4
42    Week 4 6 4
43 6.1 5
44 6.2 6
45 6.3 7
46 6.4 8
47 6.5 9
48 6.6 10
49    Week 5 7 11
50 7.1 11
51 7.2 12
52 7.3 12
53 7.4 13
54 7.5 14
55 7.6 15
56    Week 6 8 17
57 8.1 18
58 8.2 19
59 8.3 20
60 8.4 21
61 8.5 22
62 8.6 22
63    Week 7 9 23
64 9.1 24
65 9.2 26
66 9.3 27
67 9.4 28
68 9.5 29
69 9.6 31
70    Week 8 10 34
71 10.1 36
72 10.2 37
73 10.3 38
74 10.4 39
75 10.5 39
76 10.6 40
77    Week 9 11 44
78 11.1 45
79 11.2 47
80 11.3 48
81 11.4 52
82 11.5 55
83 11.6 56
84    Week 10 12 57
85 12.1 58
86 12.2 60
87 12.3 61
88 12.4 63
89 12.5 64
90 12.6 65
91    Week 11 13 68
92 13.1 70
93 13.2 72
94 13.3 74
95 113.4 76
96 135 77
97 13.6 80
98    Week 12 14 81
99 14.1 84
100 14.2 85
101 14.3 86
102 14.4 87
Reference


Table adapted from Westerway (2015) PDF and <pubmed>11065037</pubmed>

Links: Ultrasound | Fetal Development

Pages in category ‘Fetal’

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