ICAR AICE-JRF/SRF (PhD) · 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 AICE-JRF/SRF spread across the units of Veterinary Histology, Embryology & Developmental Anatomy. Difficulty: 0 easy, 25 medium, 22 hard.
| Systemic histology | 7 | |
| General embryology and developmental anatomy | 6 | |
| Ultrastructure and electron microscopy | 5 | |
| Histoenzymology and immunocytochemistry | 5 | |
| General histology | 5 | |
| Histological and histochemical techniques | 4 | |
| Gametogenesis | 4 | |
| Neuroanatomy | 4 | |
| Development of the urogenital organs | 3 | |
| Applied embryology and teratology | 2 | |
| Endocrine anatomy | 2 |
Choose an answer, then open the working. Each explanation says why the right answer is right and why the others are not.
Why is EDTA preferred to nitric acid for decalcifying a bone biopsy on which immunohistochemistry is planned?
A. EDTA chelates calcium slowly and preserves antigens and nuclear staining
EDTA removes calcium by chelation at near-neutral pH; it is slow (days to weeks) but gentle, preserving epitopes, enzymes and nucleic acids. Strong acids are fast, which is why the tempting answer that EDTA is faster is wrong; overused acids damage nuclear staining and antigens. EDTA does not fix tissue and does not dissolve collagen.
Further reading: Bancroft's Theory and Practice of Histological Techniques
A foal with chronic rhinitis and recurrent pneumonia has immotile respiratory cilia. Electron microscopy of a nasal biopsy is most likely to show:
B. Absent or defective dynein arms on the axonemal doublets
Primary ciliary dyskinesia is an inherited defect in axonemal structure, most often missing or shortened dynein arms, which leaves cilia (and sperm tails) immotile, so mucociliary clearance fails. It is reported in dogs and other species. Microvilli and tight junctions are not the motile apparatus, and stereocilia are long microvilli, not a substitute for cilia.
Further reading: Eurell and Frappier, Dellmann's Textbook of Veterinary Histology
Which intermediate filament protein is characteristic of astrocytes?
D. Glial fibrillary acidic protein
Intermediate filaments are tissue-specific: glial fibrillary acidic protein in astrocytes, desmin in muscle, cytokeratins in epithelium, neurofilaments in neurons and vimentin in mesenchymal cells. Neurofilament is the tempting choice because astrocytes are nervous tissue, but it marks neurons.
Further reading: Eurell and Frappier, Dellmann's Textbook of Veterinary 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 cartilage lacks a perichondrium?
D. Fibrocartilage of the intervertebral disc annulus
Fibrocartilage, with rows of chondrocytes between type I collagen bundles, blends with dense connective tissue and has no perichondrium; it forms the annulus fibrosus, menisci and pubic symphysis. Elastic cartilage and most hyaline cartilage (except articular cartilage) are covered by perichondrium, from which they grow appositionally.
Further reading: Eurell and Frappier, Dellmann's Textbook of Veterinary Histology
Why does bronchopneumonia in cattle typically show a sharply demarcated lobular pattern?
C. Complete interlobular septa limit collateral ventilation between lobules
Cattle and pigs have thick, complete interlobular connective tissue septa, so lobules are separate units with little collateral ventilation, and lesions stop at the septa. Cattle do have alveolar macrophages, club cells and pleura, so the other options are false.
Further reading: Eurell and Frappier, Dellmann's Textbook of Veterinary Histology
In a bull, one cycle of the seminiferous epithelium lasts 13.5 days, spermatogenesis spans 4.5 cycles, and epididymal transit takes 10 days. Approximately how long after a spermatogonium begins its divisions will the resulting spermatozoa appear in the ejaculate?
A. About 71 days
Spermatogenesis = 13.5 x 4.5 = 60.75 days; adding 10 days of epididymal transit gives 70.75, about 71 days. 61 days forgets epididymal transit; 24 days adds 13.5 and 10 without multiplying; 135 days multiplies 13.5 by 10. The practical lesson is that semen damaged by fever or heat stress must be re-examined about two months or more later.
Further reading: Senger, Pathways to Pregnancy and Parturition
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
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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