‘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 Lumen of intestine 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 Posterior dorsal fin Caudal Fin with pigment Spinal cord cells Notochord intestine Anus in Small dots are Cloaca chromatophores w/ melanin = 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 maleAnterior lamprey & posterior dorsal fins 7 gill slits Caudal fin eye Buccal funnel Largest adults grow to 4’ and 5 lbs. 1 2 3 4 5 6 7 eye 7 gill slits Lateral line pores of lateral line system Lidless eye External view of Valved