‘AMMOCOETES’ : the freshwater larva of the primitive Agnathan, Cyclostome Chordate known as the sea lamprey (Petromyzon marinus) and an adult dissection
Midsagittal section of lamprey adult Parker TJ, Haswell WA head
John E.B. Baker, MIKROGEO Caudal fin
7 mm larva
lV Anus & cloaca
Oral hood around vestibule & mouth / Brain / Otic capsule / Gill slit / Dorsal fin / Notochord /Dorsal Hollow Nerve Cord
Olfactory naris & pit eyes
1 2 3 4 5 6 7
Buccal cirri or l ll lll oral papillae endostyle Heart / Liver / Pronephros / Typhlosole in intestine Velum 1-7 are the 7 visceral pouches separated by 8 arches with gill lamellae Oral area Pharynx trunk
four cross sections of the Tail ammocoete seen as white dashed lines & roman numerals in the 2nd slide Cartilaginous skeleton of a cyclostome
Chondrocranium supporting head & oral funnel apparatus Cartilaginous Branchial basket of adult lamprey Region of cloaca
Caudal fin
not ochord
Dorsal fin cart. Ray- post. Dorsal fin n cart. Ray- ot oc ant. ho rd
Pericardial Rasping keratinized tongue cartilage for cutting into body wall of host fish to suck blood & body fluids PROSENCEPHALON Telencephalon Diencephalon (Olfactory) w/ eyes Mesencephalon
Pineal or 3rd eye
Naris & olfatory sac Rhombencephalon
cartilage Eyes, nonfunctional Nasohypophyseal in larvae pouch (‘ant. pituitary’)
VELUM hood
Buccal cirri or cartilage oral papillae
Otic Vesicle – Inner ear Pronephros – dark area around esophagus and above heart
Dorsal fin
myomeres Spinal cord
Notochord
Esophagus arch8 Esop hagus Ventricle Atria arch7 Liver
Sinus venosus Heart ‘kidney’ Otic Another 7 mm capsule ‘ammocoete’ larva eye
Gall bladder
cloaca velum
eye Pronephros or Gall bladder ‘kidney’ heart
esophagus four cross sections of another ammocoete seen as black lines & numerals in the wholemount slide at lower right Post cloacal tail 4 ‘head’ or oral area 1
‘trunk’ 3
4 3 2 1
Branchial - Pharyngeal region 2 General Circulation: Red = oxygenated blood, Blue = CO2 rich blood
Sinus Venosus Anterior Cardinal Vn Posterior Cardinal vn Common Cardinal Vn Dorsal Aorta Caudal Art. & Vn
Ventral Aorta Ventricle Portal vn in Liver
Anterior Cardinal Vn Atrium of heart
Dorsal Aorta I – Oral Dorsal area Telencephalon of Brain with Olfactory sac
Myomere
Oral cavity
Cirri - sensory
lip
Annular cartilage of Ventral hood Brain – Telencephalon front of Prosencephalon
Nasohypophyseal sac Another 2 views of the head region farther back (caudal) & into the branchial region – note gill filaments and one through oral Rhombencephalon hood and brain Dorsal & ventral aortas
N
Rods and plates of Olfactory pt. of branchial basket Prosencephalon cartilages
Ciliated region of pharynx (epi-, & hypobranchial)
Cartilage of brain case
Buccal cirri or oral papillae II–pharynx or pharyngeal Muscular (skeletal- region or striated) pharyngeal MYOMERES, basket separated by Myosepta Spinal cord, a dorsal hollow nerve cord
NOTOCHORD
Next slide Paryngeal Salivary Gland basket with passages for Dorsal aorta water to outside from pharynx to Epibranchial fold & gill slits groove, ciliated Visceral or branchialfurrow The 2 visceral cartilages above & Digestive part of pharynx- will below the ‘closing become more dorsal plate’ of the visceral furrow between gill Hypobranchial slits groove, ciliated
3 arrows show Endostyle on direction of ventral floor of oxygenated water pharyngeal region through gill – becomes lamellae thyroid in adult myotomes Spinal cord
Efferent Art. Notochord To Dorsal Aorta
Epibranchial Branchial area fold & or groove pharyngeal Branchial cross furrow section Water flow Gill Filament
Gills Gill Lamellae
Cartilages Cartilages
Endostyle Afferent art. From ventral aotae Larva Adult Adult Gill Filaments & Gill Lamellae Inside (gut) outside (external slits)
Central venous sinus
Afferent filament arteries Lamellae - gas exchange
Mitochondria-rich cells or chlorine cells for osmoregulation Filament
Efferent filament arteries Blood flow
Water flow Larval Gill Filaments & Gill Lamellae 2 respiratory gill filaments of pharyngeal basket
Mitochondria-rich cells or chlorine cells for osmoregulation
C.T.
Mitochondria-rich cells or chlorine cells for osmoregulation
gi C.T. lls
Branch of aortic arch
Gill Filament Gill Lamellae Dorsal & Ventral visceral cartilages on right side
‘closing plate’ over visceral furrow Hypobranchial Groove ciliated
Single opening from endostyle to gut Ventral aorta & 2 aortic arches (L&R)
Endostyle (high Iodine)
Transverse muscle Endostyle on ventral floor of pharyngeal region- mucus secreting– becomes thyroid in blood sucking Visceral (Branchial) cartilage parasitic adult notochord
Anterior (cephalic) cardinal veins
Dorsal aorta
gill lamellae
gill lamellae
Ciliated epithelium of upper (epibranchial) region of pharynx, next slide Dorsal aorta
Ciliated epithelium of upper (epibranchial) region of pharynx III - Abdominal region
Spinal cord, a dorsal MYOMERES hollow nerve cord NOTOCHORD
Fatty adipose tissue posterior to Pronephros Dorsal Aorta (‘kidney’)& Pronephric duct (mesonephric or Wolffian duct)
Cardinal Veins Intestine/esophagus with spiral fold or Typhlosole to increase surface area Liver
Next slide: Gall Bladder Liver cords with blood
Bile ducts
GALL BLADDER Intestine with Typhlosole (a spiral valve) Dorsal Aorta
Posterior (caudal) Cardinal veins
Fatty adiposse tissue posterior to Pronephros Pronephric (Archinephric) duct future Mesonephric or Wolffian duct of adult
Spiral fold or Typhlosole of intestine note mesenteric artery and portal vein and small segment of Liver
Visceral & parietal coelom peritoneum Microvilli on columnar cells of intestine, note junctional complexes
Columnar epithelium Detritus and diatom of int. mucosa frustules of muddy ‘filter feeding’ food supply
Portal vein
Nucleated erythrocytes in mesenteric art. TYPHLOSOLE
small segment of Liver, also a major blood cell formation zone Detritus- mucous bollus of food
Portal vn Blood cell forming tissue in typhlosole Diatom frustules in food MICROVILLI
Columnar epithelium
Coelom Pronephros (‘kidney”)
Pronephric (‘archinephric’) duct
Lu me n o f in tes tine Trunk area of another specimen
Next slide – spinal cord
Pronephros, ‘kidney’
Pronephric or Archinephric duct
Typhlosole
Diatomaceous, coagulated food in intestine Large Neuron cell bodies Central canal of Spinal Cord Arachnoid space
Pia mater
Capillaries (?) in Pia Sheath NOTOCHORD Cartilage SKIN – no scales
Epidermis with many mucus secreting gland (goblet) cells
2 ‘granular cells’
Dermis with some pigment cells - melanin
Subcutaneous tissue/ muscle Melanin-rich chromatophores in skin of larva (WM)
Color changing capabilities neuronal & hormonal control e.g. Pineal complex Epidermis with many mucus secreting gland (goblet) cells
Dermis with some pigment cells - melanin
Subcutaneous tissue/ muscle IV – tail region - post cloacal
Dorsal becomes Caudal fin
Caudal artery and vein
Spinal cord, a dorsal hollow nerve cord MYOMERES
NOTOCHORD
Nucleated erythrocytes of blood Caudal Fin with pigment Posterior dorsal fin cells
cord Spinal hord Notoc
ne intesti
Small dots are Anus in chromatophores w/ melanin Cloaca = melanocytes Note: tail fin, myomeres,mucus gland cells in epidermis, notochord, spinal cord
Caudal artery and vein 1) Freshwater larvae (~7mm @ hatching) grow as diatom loving, filter-feeders for 4-6 years. 2) The Ammocoetes larva metamorphoses into the adult as follows: 3) The subpharyngeal ‘gland’ or endostyle becomes the thyroid gland ventral to the pharynx. 4) The oral hood becomes the buccal funnel with keratin covered teeth & tongue and a circular mouth with a an annular cartilage and lingual cartilage. 5) The paired eyes become functional & move to the suface of the head. 6) The velum become more degenerate. 7) The continuous dorsal fin breaks into anterior & posterior dorsal fins with a single caudal fin. 8) The Gallbladder disappears. 9) The dorsal Digestive tube of pharynx becomes cut off from more ventral phangeal respiratory area. 10) The juveniles (~150mm) migrate to the ocean from the coastal rivers (except for landlocked forms of the Great Lakes) and become sexually mature parasitic, carnivorous adults for about 2 years before the returning to freshwater as the cycle begins anew.
wikipedia Published by NY, Vt, Great Lakes Parker TJ, Haswell WA
Adult Lamprey Dissection
Median sagittal section of head region Papillae, or lip tentacles
Keratin covered tooth
Tongue, also with teeth
Buccal Funnel Used to suction on to the side of a host , like a lake trout or salmon, and use tongue-teeth to gnaw a ~2 cm hole through the body wall to suck out blood & body fluids Midsagittal section
Teeth of Buccal or Oral Funnel Hold host flesh while tongue rasps
Note denticles of rasping tongue Tongue tooth 0.5-3 mm
Prionodus sp Aphelognathus sp
Cambrian to Triassic tooth-like, microscopic oral funnel apparatus of CONODONTS: these fossils belonged to Paleozoic Agnatha related to Cyclostmes Rhodesognathus sp
Paltodus sp Dorsal view, head
Single naris or nasohypophyseal opening Surface and sectioned view rd oral cecum of pineal or 3 eye – sees & regulates diurnal activities Annular Cartilage notochord Annular Muscle Olfactory membrane folded in olfactory sac
Hypophyseal region
Oral cavity Lingual cartilage: acts like a piston arm, moving rasping tongue
Median sagittal section of head region 15 inch / 37.5 cm adult male lamprey
eye 7 gill slits Anterior & posterior dorsal fins
Buccal Caudal fin funnel
Largest adults grow to 4’ and 5 lbs. 1 2 eye 3 4 5 6 7
7 gill slits Lateral line pores of lateral line system
Lidless eye External view of Valved Gill Slit
Lateral line pores ‘Head’ and branchial cartilages
Arcualia - future neural Annular Cartilage arch elements
hord 2 dorsal cartilages notoc
1 2 3 4 5 6 7
1
Lingual cartilage Pericardial cartilage & transverse septum Posterior cardinal veins
notochord
in testine
heart LIVER
Pericardial cartilage & transverse septum Skinned area of trunk showing myomeres and intervening myosepta arranged in characteristic ‘W’ fashion anterior
skin
Sideways ‘W’ Pleuroperitoneal cavity opened to show flat Kidney, testis and thin Intestine ( no stomach )
Kidney
testis
Intestine cephalic
cloacal opening
Medial section of caudal / ventral region, showing cloacal opening , anterior-cephalic- to right notochord A Spinal cord B
Leaking injection of blue latex
Posterior Cardinal Veins
Testis LIVER
Dorsal Aorta Hepatic A B C D art. CDTransverse (cross) sections: Catilaginous fin rays Caudal trunk Post cloacal tail
Myomeres & Myosepta
Spinal cord Spinal cord
Dorsal aorta Dorsal aorta
Caudal Vein
Posterior or caudal Cardinal Veins testis notochord
intestine A B C D Anterior Posterior and Anterior Cardinal veins merge to form the Common Cardinal Vein ( duct of Cuvier ) which quickly becomes the Sinus Venosus
Pericardial cartilage in Heart transverse septum
Dorsal Aorta
ACV PCV
8th arch Ventricle (1) Sinoatrial opening Atrium
Atrium(1), almost AV surrounds opening Ventral Aorta ventricle Anterior Inferior jugular vn. Muscular Trabeculae carneae underlying endothelial lining of Ventricle Respiratory tube & slits
esophagus
li ngu al c art
Annular muscles
Muscles that move lingual cart, & rasping tongue like a piston Folded Olfactory mucosa (‘smell’) in Sac
Naris or Olfactohypophyseal Pineal ( Pineal & opening Parietal) Gland or 3rd Eye
BRAIN
flap Cartilage of Chondrocranium
‘Hypophyseal Anterior pouch’ Choroid Plexus Pineal
Rhombencephalon
Ventricles of brain N
is’ ys ph yo ch ‘H ou l p ea ys ph po Hy
BRAIN Anterior Spinal cord or ‘dorsal, hollow nerve cord’
Arachnoid space
Anterior Notochord
Dorsal Aorta with efferent (from gills) branchial branches loaded w/ O2
esophagus Review sagittal sections
Respiratory tube & slits