embryonic period Flashcards

1
Q

Anterior visceral endoderm

A

Hypoblast cells migrate to the future cranial end of the embryo
Cranial end establishment: occurs before gastrulation
Important for head formation: transcription factors, OTX2, LIM1, HESX1, secreted factor Cerberus. All are inhibitors of nodal (pro caudal factors) activity in the cranial end of the embryo

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2
Q

Primitive streak initiated by…

A

Nodal (TGFB family)
Caudal end establishment

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3
Q

The node in the dorsal region is the organizer. Maintain by…

A

Nodal & HNF-3B

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4
Q

Once the streak is formed…

A

BMP-four is secreted throughout the bilaminar disc

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5
Q

BMP4 and FGF

A

Ventralize the mesoderm to contribute to kidneys, blood, and boy wall mesoderm.

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6
Q

Goosecoid activates chord, nagging and follistatin which…

A

Inhibit BMP expression of the dorsal mesoderm in the cranial region.
Ventralization is inhibited in the dorsal mesoderm of the cranial end of the embryo.
Regulate head formation

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7
Q

Brachyury T

A

Gene regulates the dorsal mesoderm in the middle and caudal regions. It encodes a transcription factor that binds to a T box in the DNA. It is expressed in the node, notochordal precursor cells and notochord.

Ventralization is inhibited in the dorsal mesoderm of the middle and caudal regions of the embryo.

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8
Q

Hox-C

A

Important in craniocaudal axis

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9
Q

Derivatives of the three germ layers

A

Endoderm, mesoderm, ectoderm

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10
Q

Paraxial mesoderm

A

Muscles of the head
Striated skeletal muscle
Skeleton except cranium
Dermis of skin
Connective tissue

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11
Q

Intermediate Mesoderm

A

Urogenital system including gonads, ducts, and accessory glands

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12
Q

Lateral mesoderm

A

Connective tissue and muscle viscera
Serous membranes of pleura, pericardium, and peritoneum
Primordial heart
Blood and lymphatic cells
Spleen
Suprarenal (adrenal) cortex

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13
Q

Mesoderm (Head)

A

Cranium
Connective tissue of head

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14
Q

Ectoderm

A

Neuroecotoderm
Surface ectoderm

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15
Q

Surface ectoderm

A

Epidermis, hair, nails, cutaneous glands, and mammary glands
Anterior part of pituitary gland
Enamel of teeth
Internal Ear
Lens of the eye

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16
Q

Neuroectoderm

A

Neural Crest
Neural Tube

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17
Q

Neural Crest

A

Cranial and sensory ganglia and nerves
Medulla of suprarenal gland (adrenal medulla)
Pigment cells
Pharyngeal arch cartilages
Head mesenchyme and connective tissue (visceral skeleton of head, and neck)
Bulbar and coral ridges in heart
Parafollicular cells of thyroid gland
Meninges except dura mater

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18
Q

Endoderm

A

Epithelial parts of Trachea, Bronchi, Lungs, of gastrointestinal tract, liver, pancreas, urinary bladder, urachus, pharynx, thyroid gland, tympanic cavity, pharyngotympanic tube, tonsils, parathyroid glands

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19
Q

By the beginning of the 3rd week, the paraxial mesoderm begins to organize into segments called somitomeres

A

the paraxial mesoderm begins to organize into segments called somitomeres

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20
Q

First appears in the 20th day in the…

A

cephalic region, then cephalocaudally

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21
Q

In the head region, somitomeres contribute to…

A

mesenchyme of the head

22
Q

Paraxial mesoderm to segmented somites

A

Dermatome
Myotome
Dermatome

23
Q

Lateral plate mesoderm

A

Somatopleure
Splachnopleure

24
Q

Somatopleure

A

Parietal (somatic) mesoderm and ectoderm

25
Q

Splanchnopleure

A

Visceral (splanchnic) mesoderm and endoderm

26
Q

Parietal layer of the mesoderm contributes to

A

Serous membranes of pleura, pericardium, and peritoneum
dermis of the skin except in the neck, back, sides

27
Q

Visceral layer of the mesoderm contributes to

A

the serous membrane lining the organs of the abdominal cavity

28
Q

Endodermal Layer

A

Gastrointestinal tract

29
Q

Bucopharyngeal membrane

A

ruptures during the 4th week (open connection between the amniotic cavity and the primitive gut)

30
Q

Cloacal membrane

A

ruptures during the 7th week for the anus

31
Q

The midgut temporarily communicates with the yolk sac by means of the vitelline duct

A

Later the vitelline duct is obliterated and the midgut obtains its free position in the abdominal cavity

32
Q

By two months the yolk sac becomes redundant and shrivels away

A
33
Q

Blood vessels form by

A

Vasculogenesis
Angiogenesis

34
Q

Vasculogenesis

A

Vessels arise from blood islands (mesoderm of yolk sac and lateral plate mesoderm)
Celulas del mesodermos de las islas de sangre se rearreglan por factores de crecimiento (VEGF) formando hemangioblastos. Los hemangioblastos van a ser tanto prepulsores de las células de la sangre como la de los vasos sanguíneos. Luego ocurre un rearreglo para la formación de lumen del vaso sanguíneo

35
Q

Angiogenesis

A

New vessels sprout from existing ones

36
Q

Hemangioblast cells give rise to

A

Angioblasts
Hematopoietic stem cells

37
Q

Blood island of the yolk sac are

A

transitory

38
Q

Definitive hematopoietic stem cells arise from mesoderm surrounding the aorta. Eventually, these cells will colonize the…

A

liver (9 weeks)

39
Q

At 12 weeks blood production arises from

A

Spleen and thymus (becomes the major hematopoietic organs of the fetus)

40
Q

At 28 weeks stem cells form the liver colonize…

A

Bone marrow

41
Q

By the end of the 3rd week, the heart tubes have fused to form a tubular heart

A
42
Q

Dorsal aortas se fusionan en el centro

A
43
Q

Endocardial heart tube se fusionan en el centro y de ahi se forman las cámaras del corazón

A
44
Q

Fourth week (day 22)

A

Formation of somites, neurulation occurring, neuropores formation

45
Q

Fourth week (day 23)

A

Optic groove (primordial of eye)
Neural folds fusing to form primary brain vesicles
Caudal neuropore

46
Q

Fourth week (day 24)

A

Rostral neuropore closing
First arch (mandibular)
Second (hyoid) arch
Heart prominence
Caudal (posterior) neuropore open

47
Q

Fourth week (day 26)

A

Forebrain prominence
Third pharyngeal arch
Caudal eminence

48
Q

Fourth week (day 28)

A

Fourth pharyngeal arch
Lens placed (primordial of lens)
Upper limb bud
Lower limb bud

49
Q

Fifth Week

A

Minor body changes
Growth of head (toward heart prominence)
Cervical Sinus is visible
Mesonephric ridges- future site of mesonephric kidneys

50
Q

Sixth week

A

Larger hand plates
Digital rays
Spontaneous movements
Reflex responses to touch
Eyes are obvious
Head larger than trunk
Auricular hillocks- external auditory canal and ear

51
Q

Seventh week

A

Notches between digital rays appear
Umbilical herniationn

52
Q

Eighth week

A

Tail like caudal eminence is present at the beginning, but then disappears
Band around the head, scalp vascular plexus
Digits completely separated
Purposeful limb movement- ossification occurs in the femur
Distinct human characteristics, but still disproportion between head and trunk