ICAR AIEEA (PG): Master's entrance, Veterinary Science and Animal Sciences · India · NTA for ICAR
Original practice questions written to the published syllabus · not past papersTissues and organs at microscopic and ultrastructural level, and how the body develops from gametes to organs. Teratology explains many congenital defects met in practice.
In the exams: ICAR AICE-JRF core group 07; ICAR AIEEA-PG 13 (Anatomy)
ICAR AIEEA (PG), Code 13 Veterinary Science (Anatomy), and ICAR AICE-JRF/SRF core group 07 (Anatomy)
Comparative recall and reasoning across the whole subject: fixatives and special stains, organelle ultrastructure and junctions, epithelial and gland types, species differences in the digestive, respiratory, lymphoid and urogenital organs, pituitary and adrenal zonation, spermatogenesis and oogenesis, placental classification, germ-layer and pharyngeal-pouch derivatives, and named congenital anomalies such as the freemartin. JRF questions push further into histoenzymology, immunocytochemistry and developmental mechanisms (SRY, anti-Mullerian hormone, ureteric bud induction).
How our questions for ICAR AIEEA spread across the units of Veterinary Histology, Embryology & Developmental Anatomy. Difficulty: 24 easy, 23 medium, 13 hard.
| Systemic histology | 12 | |
| General histology | 8 | |
| General embryology and developmental anatomy | 8 | |
| Histological and histochemical techniques | 7 | |
| Ultrastructure and electron microscopy | 6 | |
| Gametogenesis | 5 | |
| Neuroanatomy | 4 | |
| Development of the urogenital organs | 3 | |
| Endocrine anatomy | 3 | |
| Histoenzymology and immunocytochemistry | 2 | |
| Applied embryology and teratology | 2 |
Choose an answer, then open the working. Each explanation says why the right answer is right and why the others are not.
A 40x objective is used with a 10x eyepiece. What is the total magnification?
C. 400x
Total magnification is objective x eyepiece = 40 x 10 = 400x. Adding the two gives 50x, a common slip; 4,000x is a tenfold error.
Further reading: Mescher, Junqueira's Basic Histology
Why are fresh frozen sections, rather than paraffin sections, normally used for enzyme histochemistry?
A. Processing inactivates most enzymes
Histoenzymology shows enzyme activity, not the enzyme protein, and the heat of wax infiltration plus dehydration and clearing destroy most enzymes. Frozen sections are usually thicker, not thinner, than paraffin sections. Enzymes exist in fixed tissue as proteins but lose activity, so immunohistochemistry can still detect them.
Further reading: Bancroft's Theory and Practice of Histological Techniques
A round-cell tumour from a dog's lymph node is strongly positive for CD3 and negative for CD79a. The tumour cells are most likely:
D. T lymphocytes
CD3 is part of the T-cell receptor complex and is the standard T-cell marker; CD79a is a B-cell (and plasma-cell) marker, so CD3+ CD79a- indicates T-cell lymphoma. Histiocytes are identified by other markers such as CD18 or Iba1 and are CD3-negative.
Further reading: Zachary, Pathologic Basis of Veterinary Disease
Which epithelium lines most of the trachea?
D. Pseudostratified columnar ciliated epithelium with goblet cells
The conducting airway is lined by pseudostratified columnar ciliated epithelium with goblet cells, the mucociliary escalator. It looks layered because nuclei are at different heights, but every cell touches the basement membrane. Stratified squamous epithelium is found in the nasal vestibule and pharynx; transitional epithelium lines the urinary tract.
Further reading: Eurell and Frappier, Dellmann's Textbook of Veterinary Histology
Which domestic mammals have oval (elliptical) red blood cells?
A. Camelids such as camels, llamas and alpacas
Camelids are the only mammals with oval erythrocytes; like other mammalian red cells they lack a nucleus. Birds and reptiles also have oval red cells, but theirs are nucleated. Horse and cat red cells are round discs that form rouleaux; goat red cells are round and very small.
Further reading: Eurell and Frappier, Dellmann's Textbook of Veterinary Histology
Which structure identifies the thymus in a histological section?
C. Thymic (Hassall's) corpuscles in the medulla
Thymic corpuscles, concentric whorls of epithelial reticular cells in the medulla, are unique to the thymus. Germinal centres are features of lymph nodes, spleen and mucosal lymphoid tissue; periarteriolar sheaths belong to the splenic white pulp; the subcapsular sinus is a lymph node feature.
Further reading: Eurell and Frappier, Dellmann's Textbook of Veterinary Histology
The teat canal (streak canal) of the cow is lined by:
B. Keratinised stratified squamous epithelium
The teat canal is lined by keratinised stratified squamous epithelium whose keratin plug, with the surrounding sphincter, is a key barrier against bacteria entering the udder. The teat and gland cisterns above it are lined by a double layer of cuboidal to columnar cells.
Further reading: Eurell and Frappier, Dellmann's Textbook of Veterinary Histology
A cryptorchid stallion shows stallion behaviour but is infertile when both testes are retained in the abdomen. Why?
C. Leydig cells still make testosterone, but the high temperature prevents spermatogenesis
Testosterone production by Leydig cells continues at body temperature, so male behaviour persists, but spermatogenesis needs a temperature a few degrees below core, so bilaterally retained testes produce no spermatozoa. Cryptorchidism has a hereditary component, so affected animals should not be bred.
Further reading: McGeady et al., Veterinary Embryology; Noden and de Lahunta, The Embryology of Domestic Animals
What are the three layers of the cerebellar cortex, from surface inwards?
C. Molecular, Purkinje cell, granular
The cerebellar cortex has an outer molecular layer, a single row of Purkinje cells, and an inner granular layer packed with granule cells. Pyramidal cells are the output neurons of the cerebral cortex, which has six layers.
Further reading: Eurell and Frappier, Dellmann's Textbook of Veterinary Histology
Compared with primates, why do domestic ungulates depend heavily on brainstem (extrapyramidal) motor pathways for voluntary movement?
A. Their corticospinal tract is small, and few fibres pass beyond the cervical cord
The corticospinal (pyramidal) tract is much smaller in domestic animals than in primates, and in ungulates few fibres reach beyond the cervical cord, so brainstem motor centres and their tracts carry most voluntary motor control. Ungulates do have a motor cortex and ventral horns, and Purkinje cells project to cerebellar and vestibular nuclei, not the cord.
Further reading: de Lahunta, Veterinary Neuroanatomy and Clinical Neurology
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