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Vet Embryology Final
TAMU CVM Embryo final
| Question | Answer |
|---|---|
| What are the divisions of the mesoderm? | Paraxial, intermediate, splanchnic, somatic |
| What 4 body folds establish the ventral body surface? | Head, tail, Right and left lateral folds |
| What two area of the embryo have ectoderm contacting endoderm? | Buccopharyngeal membrane & cloacal |
| What 3 rudimentary organs start cranial to the head? | Septum transversum, heart tube, buccopharyngeal membrane |
| What folds develop to close off the body cavities? | Pleuropericardial folds (seperates the plueural and cardial cavities), pleuroperitoneal fold (seperates pleural and peritoneal cavities) |
| What is the blood supply of the foregut tube? | Celiac Artery |
| What is the blood supply of the midgut tube? | Cranial mesenteric artery |
| What is the blood supply of the hindgut tube? | Caudal mesenteric artery |
| What makes up the 1st pharyngeal arch? | Maxillary and mandibular prominences |
| What comes from the 2nd and 3rd Pharyngeal arches? | The hyoid bones |
| What comes from the 4th Pharyngeal arch? | The larynx |
| What comes from the 5th Pharyngeal arch? | Nothing - it doesn't form |
| What comes from the 6th Pharyngeal arch? | The larynx |
| What is between the pharyngeal arches? | Pharyngeal clefts |
| What are the skeletal and muscular derivatives from the 1st arch? What is the innervation? | Skeletal - incus and malleus; Muscular - Muscles of mastication; Innervation - CN 5 |
| What are the skeletal and muscular derivatives from the 2nd arch? What is the innervation? | Skeletal - stapes & a portion of the hyoid bones; muscular - muscles of facial expression; Innervation - CN VII |
| What are the skeletal and muscular derivatives of the 3rd arch? What is the innervation? | Skeletal - contributes to the hyoid bones; Muscular - stylopharyngeus m. ; Innervation CN IX |
| What are the skeletal and muscular derivatives of the 4th arch? What is the innervation? | Skeletal - contributes to the larynx; Muscular - pharyngeal constrictors & cricothryoid; Innervation CN X |
| What are the skeletal and muscular derivatives of the 5th arch? What is the innervation? | Nothing - it doesn't form |
| What are the skeletal and muscular derivatives of the 6th arch? What is the innervation? | Skeletal - contributes to the larynx; Muscular - intrinsic muscles of the larynx; Innervation CN X |
| Where does the lens and nasal placodes form? | The frontonasal process |
| What is associated with the frontonasal process? | Intermaxillary segment which forms the primary palate, the philtrum of the lip and the 4 incisor teeth |
| What forms the secondary palate? | The maxillary processes |
| Where does the thymus? | The thyroid diverticulum, then it moves caudal. |
| What forms the C-cells? | Ultimobrachial body |
| What is the vitelline duct? | It is the yolk stalk for the yolk sac |
| What does the dorsal mesentary in the region of the stomach? | Dorsal mesogastrium |
| What is the adult reminant of the Umbilical vein? | Round ligament of the liver |
| What is th urachus? 4 Part of the allantois extending from the urinary bladder to the umbilicus | |
| What layer does the reproductive organs come from? | Intermediate mesoderm - gonadal ridge |
| What forms the gametes? | Primordial germ cells |
| What is the beginning of the sexual dimorphism? | Male - Wolffian duct; Female - Mullerian duct |
| What forms the efferent ductules and the rete testis? | Mesonephric tubules |
| What forms the testis cord? | Gonadal cords. |
| What forms the seminiferous tubules? | The medullary region of the gonadal cord |
| What do spermatogonia and oogonia cells come from? | Primordial germ cells |
| Where do the Sertoli cells come from? | Mesonephric tubules epithelial cells |
| Where do the intersitial cells come from? | Mesodermal mesenchyme cells @ the gonadal ridge |
| What happens when ovaries form? | Gonadal cords degenerate; and cortical cords form |
| What is special about the mare ovary? | Follicles are located throughout the ovary - instead of just around the perphery. |
| What does the Paramesonephic duct form? | uterine tube horns, body & cervix of the uterus and the proximal vagina |
| Define Uterus masculinus | It is a remnant of the paramesonephric ducts in the male. It looks like a very small uterus with horns and a body (especially seen in Stallions) |
| What are the 4 major criteria for gender determination? | 1 - Genetic (chromosomal) composition, 2- Gonadal histology, 3 - Morphology of the reproductive tract, 4 - Morphology/appearance of the external genitalia |
| Define hermaphrodite. | An animal in which one or more of the 4 sex criteria don't match the others. |
| Define true hermaphrodite. | Has gonadal tissues of both sexes |
| Define false or pseudohermaphrodite | Has gonads of one sex only and alteration of one or more other sexual characteristics. |
| Define teratogen. 4 Something that comprimises the normal development of the fetus or embryo. | |
| Define teratology. | Study of the advers effects of the environment on developing system |
| Define congenital. | present at birth. |
| Describe the effect of Thalidomide. | babies with flippers. |
| What are the 4 lessons of embryology? | 1 - This is a self cleansing system. 2 - Not all congenital defects are malformations, 3 - congenital defects are often multifactorial in etiology, 4- An educated guess is better than no guess at all :) |
| Describe the post conception embryonic loss numbers at 2 weeks. | 31% lost within two weeks. (Chromosome and implantation defects) |
| Describe the post conception embryonic loss numbers at 3 weeks. | 27% lost - Infection in dam or endocrinology issues. |
| Describe the post conception embryonic loss at 8 weeks. | 10% loss - Severe malformations |
| Describe the loss potential of liveborn animals. | 7% loss - functional defects |
| Odds of a liveborn animal with a congential defect. | Out of 24 normal births 1 will have a congenital malformation. |
| Define malformation. | An intrinsic problem in embryologic differentiation or development of a structure causing it to be abnormally formed. |
| Define deformation. | An alteration in the shape/structural integrity of a limb or an organ which had previously differentiated and developed normally. |
| Define a disruption. | A structural defect resulting from the distruction of a previously formed normal structure. |
| What happens to a pre-implanted embryo when it is damaged? | Usually death. |
| What happens to an embryo if it is damaged during organogenesis? | Organ and system susceptible to malformations |
| What happens to a fetus is damaged? | Growth retardation, structual defects or functional loss. |
| Pricipals of teratology | 1 - susceptibility depends on genetics. 2 - stage influences susceptibility. 3 - Teratogenics act through specific mechanisms. 4 - Endpoints are different 5 - outcomes depends on the compound. 6 - Dose dependant. |
| What are the endpoints of abnormal development? | Death, malformation, deformation, disruption, growth retardation, functional disorder |
| Define Amelia | All of a limb missing. |
| Define meromelia | Part of a limb is missing |
| Define polydactyly | Presence of extra digits |
| Define Syndactyly | Fusion of digits |
| Define arthtogryposis | limb deformity/ by twisting or bending. |
| Define manidibular brachygnathia | Reduced length of the mandible |
| Define maxillary brachygnathia | Maxillary region is shorter than the mandible |
| What are other terms for the cerebral aqueduct? | Mesencephalic aqueduct or the aqueduct of Sylvius |
| What are the 3 layers of the neural tube? | Ventricular (makes ependymal cells), Mantle (Gray matter), Marginal layer (white matter) |
| What is the name of the canal in the spinal cord? | Central canal |
| What creates the sensory horn? | Alar plate |
| What creates the motor horn? | Basal plate |
| Define Hydrocephalus. | Accumulation of an excessive amount of CSF |
| Define Obstructive hydrocephalus | Excessive CSF that causes increased pressure. |
| Define Compensatory hydrocephalus | When brain tissue fails to form or if brain tissue is destroyed and CSF fills the space = no increased pressure |
| Define hypoplasia/atrophy | viruses that infect the cerebellum and destroys them (in cats - Feline panleukopenia virus; in cows - bovine virus diarrhea virus) |
| What does the eye develop from? | The optic vesicle & optic stalk from the diencephalon |
| Explain eye development. | Optic vesicle forms, a thickening called the lens placode, then the vesicle becomes the optic cup, The lens pit then forms then the lens vesicle |
| What layer is the lens vesicle made from? | Surface ectoderm |
| What makes up the cornea? | Ectoderm, neural crest cells, sometimes mesenchyme |
| What forms the optic nerve? | The optic stalk |
| Define anophtalmia | No eye formed |
| Define Microphthalmia | small eyes formed |
| Define Congenital cataracts | lens becomes opaque during fetal life |
| Define Collie eye syndrome | Coloboma; keyhole pupil |
| What forms the inner ear? | The otic placode |
| What forms the auditory tube and tympanic cavity? | The first pharyngeal pouch |
| Where is the respiratory diverticulum formed? (also called tracheobronchial) | It forms from a ventral groove called the laryngotracheal groove - in ruminants a 3rd bud forms the tracheal bronchus |
| What is formed by a lung bud? | 2 Primary bonchial buds and tracheal bronchus in rumies - a secondary bronchials for the lobar bronchi - then the segmental bronchi |
| What gives rise to respiratory epithelium? | Endoderm |
| What makes all the lung tissue - except epithelium? | Mesenchyme from mesoderm of splanchnopleure |
| What is Esophageal atresia? | the proximal end of the esophagus is a blind pouch. |
| What is esophagotracheal fistula? | The distal end of the esophagus leads into the trachea. |
Created by:
cproth
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