Review for the second hour exam, part two
Origins of organs and tissues:Teeth
secreted by infoldings of stomodeal ectodermal epithelium
Dentin (American spelling) or Dentine (British) (less hard, bone-like inner part of teeth)
Palate: palatal shelves: infoldings of sides of stomodeum:
Thyroid Gland: formed by invaginations of anterior endoderm epithelium.
Salivary glands: 3 pairs; the most anterior pair form as invaginations of the stomodeal ectoderm.
Lungs: invaginations in the anterior endodermal epithelium.
Liver: invaginations in the endodermal epithelium.
Pancreas: invaginations in the endodermal epithelium.
Kidney: metanephros; Posterior part of the intermediate mesoderm.
Urine duct (Metanephric duct) Posterior intermediate mesoderm.
Sperm Duct (=Vas Deferens) same as Pronephric Duct, Wolffian Duct
Seminiferous Tubules of testis, develop from genital ridge
Egg duct= oviduct : Müllerian duct; infolding in lateral plate mesoderm.
Uterus: develop from middle and posterior parts of Müllerian duct. Many vertebrates have two uteruses; and this sometimes occurs as an abnormality ("birth defect") in humans. (Notice the analogy to formation of two hearts)
Coelomic cavity: Lateral plate mesoderm
Heart: Lateral plate mesoderm
Skeletal muscles: Myotome of somites (paraxial mesoderm)
Dermis (inner layer of skin): Dermatome of somites (paraxial mesoderm)
Vertebrae: Sclerotome subdivisions of somites
Nose (nostrils): Olfactory Placodes (thickenings and infolding of somatic ectoderm)
Lenses of eyes: Lens Placodes (thickenings and infolding of somatic ectoderm)
Otic Placodes (thickenings and infolding of somatic ectoderm)
Eustachian tube: first pair of gill slits = pharyngeal pouches
Tonsils: second pair of gill slits = pharyngeal pouches
Parathyroid gland: third and fourth pairs of gill slits = pharyngeal pouches
Thymus: third and fourth pairs of gill slits = pharyngeal pouches
Brain: Neural Tube Ectoderm
Motor Nerves: Neural Tube Ectoderm
Pigmented Retina: Neural Tube Ectoderm
Neural Retina (of the eye): Neural Tube Ectoderm
Optic Nerve: axons of ganglion cells of Neural Retina
Sensory nerves: Neural crest ectoderm
Post-ganglionic autonomic nerves: Neural crest ectoderm
Melanocytes (or other pigment cells of the skin): Neural crest ectoderm
Facial bones and muscles: Neural crest ectoderm
Cloaca: proctodeum (invagination of posterior somatic ectoderm)
Bladder: develops by separation of the anterior part of cloaca.
Rectum: develops by separation of the posterior part of cloaca.
Epidermis: Outer layer of the skin: Somatic ectoderm
Hair, scales, feathers: Outer layer of the skin: Somatic ectoderm.