‘AMMOCOETES’ : the freshwater of the primitive Agnathan, Cyclostome known as the sea (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 &

Oral hood around vestibule & / / Otic capsule / slit / Dorsal fin / /Dorsal Hollow Nerve Cord

Olfactory naris & pit eyes

1 2 3 4 5 6 7

Buccal cirri or l ll lll oral papillae / Liver / / Typhlosole in intestine Velum 1-7 are the 7 visceral pouches separated by 8 arches with gill lamellae Oral area trunk

four cross sections of the Tail ammocoete seen as white dashed lines & roman numerals in the 2nd slide Cartilaginous 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 for cutting into body wall of host to suck blood & body fluids PROSENCEPHALON Telencephalon (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 – Pronephros – dark area around and above heart

Dorsal fin

myomeres Spinal cord

Notochord

Esophagus arch8 Esop hagus Atria arch7 Liver

Sinus venosus Heart ‘’ 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 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

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 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 -

Mitochondria-rich cells or chlorine cells for 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- 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 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 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 ) 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

Tongue, also with teeth

Buccal Funnel Used to suction on to the side of a host , like a or , 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 tooth-like, microscopic oral funnel apparatus of : these belonged to Paleozoic 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

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 )

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

‘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 ) branchial branches loaded w/ O2

esophagus Review sagittal sections

Respiratory tube & slits