Pan-Gnathostomata 1

Question 1

Crown Gnathostomata is defined by the split between

Answer 1

Chondrichthyes and Osteichthyes

Question 2

What are some Gnathostome synapomorphies?

Answer 2

1) increased genetic complexity
- WGD, expanded tool kit genes, Hox, taxonomic and phenotypic diversity, signal muted when fossil record is considered
2) Increased Diversity of Connective Tissue
- tissues that provide structural integrity (mostly differentiated from mesodermal mesenchyme, but can be from neural crest), separated from neighbor cells w/ ECM
- blood, loose connective tissue, dense connective tissue, cartilage, bone

Question 3

What is a big point about connective tissue in Gnathostomes?

Answer 3

It is plesiomorphic for all Gnathostomes, but its organization and complexity of apomorphic

Question 4

Information on Blood

Answer 4

Liquid CT. RBC + WBC.
ECM=plasma and is mesodermal
High diversity! Most classified are WBC

Question 5

Adaptive/Acquired Immune System

Answer 5

Specialized cells/processes: specific, selective, regulated
Innate IS is DEEPLY plesiomorphic, but identifying and targeting pathogens are gnathy

Question 6

Loose Connective Tissue

Answer 6

Adipose/Fat, no ECM

Question 7

Dense Caonnective Tissue

Answer 7

Ligaments, tendons (regular). Dermis (irregular)
- fibroblast, collagen+=ECM

Question 8

Cartilages

Answer 8

Chrondrocytes produce ECm = collagen+
Hyaline: endochondral (mesenchyme to cartilage to bone), articulated cartilage, tracheal rings, and i at joint
Fibrocartilage: resists compression, think vertebral disks & pelvic bone
Elastic: flexible @ nose tip and ears

Question 9

DifferentCell Types in Bone

Answer 9

Osteoblasts, Osteoclasts, and Osteocytes

Question 10

Osteoblast

Answer 10

Generate ECM = bone
Collagen (tensile strength)
Calcium and phosphate salts
Compressive strength
Reside in outer layer (periosteum)

Question 11

Osteoclast

Answer 11

Bone reabsorption, remodeling, mineral storehouse

Question 12

Osteocyte

Answer 12

Buried osteoblasts (lacunae)
Regulate blasts ad clasts
Canaliculi

Question 13

Bone Types

Answer 13

Compact/Cortical, Periosteum, Spongy/Cancellous
Cellular vs Acellular

Question 14

Compact-Cortical Bone

Answer 14

External part of bone; dense and strong
Osteon = structural unit

Question 15

Periosteum

Answer 15

Fibrous outer layer conveys neurovasculature

Question 16

Spongy/Cancellous Bone

Answer 16

Structural Unit: trabeculae
Internal, highly vascularized
high response to mechanical force
*Bone marrow - hematoporeisis: RBC producer
- this came before bone itself

Question 17

Cellular vs Acellular Bone

Answer 17

AC: no osteocytes; plesiomorphic type

Question 18

The Gnathostome Skeleton: Axial

Answer 18

Skull, vertebral column (regionally differentiated), ribs, sternum

Question 19

The Gnathostome Skeleton - Appendicular

Answer 19

Girdles (pectoral and pelvic) - connect limbs to axial skeleton
Limbs (forelimb and hindlimb)

Question 20

Different kinds of Skeletogenesis

Answer 20

Membraneous/perichondral/dermal: mesenchyme to bone
- gnathostome tem; ossification directly from mesenchyme precursor (periochondrium)
Endochondral: mesenchyme to cartilage to bone
- osteichthyan stem

Question 21

More Info: Axial Skeleton- Vertebral Column

Answer 21

Vertebral Column
- pre causal v caudal regions
– usually @ level of pelvic girdle; morphological changes
—monospondylous/precaudal: short neural arches & ventral basipophyes
—dispondylous/caudal: long neural arch, haemapophyses

Question 22

More Info - Appendicular

Answer 22

Dorsal, caudal, and anal fins are vertebrate stem stuff
Pelvic and Pectoral fins are Gnathostome stem stuff

Question 23

What is the Fin- Fold theory

Answer 23

1) Single continuous fin and segmented structure; Vertebrate stem
2) Distinct Median fins: dorsal, anal, caudal
3) Paired fins: pectoral and pelvic
- heterotopic transfer of signaling cascade from paraxial to lateral plate mesoderm (LPM)